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Veterinary Surgery 38:233–245, 2009

Subtotal Coronoid Ostectomy for Treatment of Medial Coronoid Disease in 263 Dogs NOEL FITZPATRICK, MVB, CertSAO, CertVR, THOMAS J. SMITH, MA, VetMB, CertSAS, RICHARD B. EVANS, JERRY O’RIORDAN, MVB, CertSAS, and RUSSELL YEADON, MA VetMB

PhD,

Objective—To document clinical outcomes after subtotal coronoid ostectomy (SCO) for treatment of medial coronoid disease (MCD). Study Design—Prospective clinical study. Animals—Dogs (n ¼ 263) with MCD. Methods—MCD was treated by a combination of SCO via mini-arthrotomy, cage confinement (6 weeks), leash restricted exercise (12 weeks) and pentosan polysulfate administration. Outcomes were assessed by clinical examination in the short-term (324 elbows), owner questionnaires (146 dogs), clinical examination (90 dogs), subjective assessment of gait (110 elbows) and radiographic examination (180 elbows), 4 months to 7 years 7 months after surgery. Results—One intraoperative complication occurred (1 elbow with fissuring of the ulna) and 8.2% elbows had immediate postoperative complications, the most common being wound infection (7%). Improvement in subjective lameness assessment to a score of 0 was noted at 5 weeks in 74.4% of elbows (veterinary) and 45.6% (owner) and at 12 weeks in 71.5% (veterinary), and 91.2% (owner). Subjective assessments of outcomes in the medium-term revealed 81.9% dogs remained sound, with significantly (Po.05) improved daily function scores compared with preoperative values, 83.5% of dogs received no NSAID. Clinical examination revealed good limb function and subjective assessment showed 51% of limbs were free from lameness. Radiographic progression of osteophytosis occurred on average by one grade. Conclusion—Management of MCD using the described management regime, including SCO via mini-arthrotomy, deserves consideration and comparison with existing treatment methods. Clinical Significance—Management of MCD by SCO can be considered when gross fissuring or fragmentation of the MCP is not evident. This technique does not require specialized instrumentation. r Copyright 2009 by The American College of Veterinary Surgeons

of thoracic limb lameness in medium to large breed dogs1,2 and is a common cause of elbow osteoarthritis (OA). The exact cause of MCD is debated but elbow incongruence has been reported as a primary contributor to pathogenesis of MCD.3–6 Management of MCD remains controversial and currently no universally agreed approach exists. Results from reported studies vary but in general, describe a

INTRODUCTION

D

ISEASE OF the medial aspect of the coronoid process (MCP) of the ulna, medial coronoid disease (MCD), is a component of elbow dysplasia and includes gross fissuring and fragmentation of the MCP, pathology of the overlying cartilage and/or subchondral bone. MCP disease has been reported as a frequently diagnosed cause

From Fitzpatrick Referrals, Eashing, United Kingdom and the Department of Veterinary Clinical Sciences, University of Illinois at Urbana-Champaign, Urbana, IL. Presented in part at The British Small Animal Veterinary Association Annual Conference, Birmingham, UK, 2006 and American College of Veterinary Surgeons annual symposium, Washington DC, USA, 2006. Address reprint requests to Noel Fitzpatrick, MVB, CertSAO, CertVR, Fitzpatrick Referrals, Halfway Lane, Eashing, Surrey GU7 2QQ, UK. E-mail: noelF@fitzpatrickreferrals.co.uk Submitted March 2008; Accepted October 2008 r Copyright 2009 by The American College of Veterinary Surgeons 0161-3499/09 doi:10.1111/j.1532-950X.2008.00491.x

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return to normal function in the short-term with progression of OA in the medium- and long- term.1,4,7–9 Some authors report that surgical intervention does not alter the long-term prognosis and favor solely nonsurgical management.9 Surgical techniques reported for MCD broadly adopt one of two approaches: osteotomy or focal treatment of the MCP, either by arthrotomy or arthroscopy. Osteotomies have also been proposed with or without fragment removal4 either to correct perceived elbow incongruity or to alter force distribution across contact areas of the elbow joint. Focal surgical treatment of MCD has included fragment removal and curettage,7,8,10–15 whereas fragment removal plus abrasion arthroplasty or micro-fracture of the visible extent of cartilage disease has been anecdotally reported.16 Conventional fragment removal, abrasion arthroplasty or osteostixis of the diseased MCP may provide short-term mitigation of clinical signs but progression of OA invariably occurs and persistence of lameness is common.1,7–9 When there is gross fragmentation of the MCP, the osteochondral fragments may sometimes contribute to frictional abrasion of the opposing medial aspect of the humeral condyle. Putatively, their role may be less clinically important than persistent cartilage and subchondral bone erosion that has been documented in the absence of free fragmentation.17 Conventional focal treatment of coronoid pathology depends on healing occurring in the persistent friction environment of the medial compartment of the elbow. More aggressive arthroplasty to lower the joint surface of the MCP by motorized shaving during arthroscopic procedures has been advocated to ameliorate the effects of ‘‘medial compartment’’ pain associated with joint surface friction.6,18 Surgical debridement of malaciac cartilage has been advocated to allow assessment of subchondral bone.17 It has been suggested that ‘‘soft’’ and ‘‘yellow’’ subchondral bone be debrided until hemorrhage of the underlying bone occurs and it resembles a more normal ‘‘hard’’ and ‘‘white’’ morphology.19 Hemorrhage may vary with raised intra-articular pressures resulting from fluid infusion during arthroscopic examination.19 These guidelines may be useful, but remain subjective and the resultant variability regarding amount of MCP debridement may fail to consistently address the extent of microscopic pathology, which is poorly delineated by arthroscopic evaluation. Use of arthroscopy for diagnosis and treatment of MCD is well accepted. Treatment of MCD using arthroscopically assisted minimally invasive techniques may have advantages over access by medial arthrotomy2 and results of a recent meta-analysis suggest that arthroscopy is superior to medial arthrotomy and medical management,20 but that treatment by medial arthrotomy is not superior to medical management. However, arthrotomy techniques used and various modalities of treatment for

MCD described in these studies (including fragment removal, curettage or removal of portions of the MCP using various instruments) are different to the technique we report and thus direct comparison is precluded. A potential disadvantage of removal of a greater portion of the MCP include aberrant and deleterious load redistribution within the joint. Our objectives were to prospectively document shortterm clinical outcomes and long- term clinical and radiographic outcomes in dogs with clinically apparent MCD using a standardized focal surgical treatment (subtotal coronoid ostectomy—SCO through mini medial arthrotomy) with standardized postoperative medical management and exercise regime. We hypothesized that treatment of MCD by SCO would lead to short-term resolution and long-term remission of lameness, and prevention of radiographic progression of OA. MATERIALS AND METHODS Between 1999 and 2007, dogs (n ¼ 246; 437 elbows) with unilateral or bilateral thoracic limb lameness attributable exclusively to MCD (based on historic, physical, radiographic and arthroscopic examination) were treated by SCO and included in this study. Dogs with concurrent orthopedic conditions of either thoracic limb based on historical, physical and radiographic examination, with supplemental arthroscopic or computer tomographic (CT) examination were excluded from this study. All dogs with unilateral or bilateral clinically evident lameness subjectively localized to the elbow joint(s) and with confirmed arthroscopic abnormalities and/or radiographic signs, in the absence of other orthopedic diseases, were considered to have MCD. Arthroscopic findings included either fragmentation or fissuring of the MCP, fibrillation and/or malacia of the cartilage overlying the MCP, and/or synovitis. Regardless of the degree of MCP pathology, all elbows were treated by SCO. Informed written consent for treatment was based on discussion of available treatment options and associated prognoses. For this study, recorded data included: (1) signalment; (2) lameness history and preoperative clinical findings; (3) radiographic, arthroscopic and peri-operative findings; (4) complications; and (5) clinical and radiographic findings at short- (o12 week) and long-term (41 year) reexamination.

Clinical Examination Lameness evaluation was subjectively assessed at a walk and trot by a single surgeon (N.F.) and categorically graded as 0 ¼ no observable lameness; 1 ¼ intermittent, mild weight-bearing lameness with minimal change in gait; 2 ¼ consistent, mild weight-bearing lameness with little change in gait; 3 ¼ moderate, obvious weight-bearing lameness with noticeable change in gait; 4 ¼ severe weight-bearing lameness- ‘‘toe-touching’’; or 5 ¼ non-weight bearing lameness. Orthopedic and neurologic examination excluded concurrent conditions. Response to el-


FITZPATRICK ET AL bow flexion, extension and elbow flexion with simultaneous supination or pronation of the antebrachium, and deep digital palpation of the medial aspect of the elbow was recorded.

Radiographic Examination Radiographic examination facilitated by deep sedation or general anesthesia included: both elbow joints (maximally extended and maximally flexed mediolateral projections and extended craniocaudal projections) and both shoulder joints (mediolateral projection). Elbows were either in direct contact with the radiograph cassette or a 100 mm radiopaque marker used to standardize image size with respect to potential magnification. The degree of elbow osteophytosis was scored by a single investigator (T.S.) as: 0 ¼ lack of osteophytosis, subtrochlear sclerosis may be present; 1 ¼ osteophytosis in 1 or more locations o2 mm in height; 2 ¼ osteophytosis in 1 or more locations, 2–5 mm in height; or 3 ¼ osteophytosis in 1 or more locations, 45 mm in height.

Arthroscopic Examination Dogs were anesthetized, positioned in dorsal recumbency, and prepared for aseptic surgery of 1 or both elbow joints. Elbow joint arthroscopic examination was performed using a medial portal with a 2.4 mm 301 angled arthroscope (Hopkins, Karl Storz, Tuttlingen, Germany) connected to a video camera and image-recording device. Arthroscopic findings were subjectively assessed and the modified Outerbridge grading score21 used to classify cartilage lesions of the MCP and medial aspect of the humeral condyle. Cartilage lesions were scored by a single examiner (N.F.) as: 0 ¼ cartilage considered normal; 1 ¼ chondromalacia; 2 ¼ partial thickness or superficial fibrillation; 3 ¼ deep fibrillation; 4 ¼ full thickness cartilage loss; and 5 ¼ full thickness loss with subchondral bone eburnation. An arthroscopic probe was used to distinguish between fissuring or free fragmentation of the MCP. Each elbow had at least 1 joint abnormality identified on arthroscopic examination including synovitis, disease of the cartilage overlying the MCP and/or fissuring or fragmentation of the MCP.

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Osteotomy of the MCP was initially created using an osteotome and mallet (n ¼ 38 elbows) and thereafter using solely an air powered oscillating saw with a 5.8 mm blade (2m141, MDM Medical, Southampton, UK). The osteotomy traversed the medial portion of the MCP from its medial border to the most caudal extent of the radial incisure cranial to the sagittal ridge of the ulnar trochlear notch (Fig 1). The cut was angled distocranially creating a triangular segment when the MCP was grossly intact. The segment was separated from annular ligament attachments and removed en bloc along with any loose fragments. Each joint was lavaged with sterile saline (0.9% NaCl) solution to remove residual bone and cartilage debris. Immediately before closure, 0.5% bupivacaine (1 mg/kg/ joint) was instilled into the joint. The joint capsule, muscles and subcutaneous tissues were closed individually with 2-0 polydioxanone using a simple interrupted pattern and the skin closed using 2-0 pseudomonofilament polyamide (Supramidt, B. Braun, Tuttlingen, Germany). Preoperative analgesia was continued with administration of opioids in response to individual requirements in the immediate postoperative period.

Postoperative Care Carprofen (2 mg/kg orally twice daily) or meloxicam (0.1 mg/kg orally once daily) were administered with choice depending on owner perception of previous response to treatment, owner personal preference, and previous drug intolerances experienced by individual dogs. Duration of administration was tailored to individual needs based upon owner assessment of lameness and dog discomfort assessed on veterinary clinical examination at the time of short-term follow-up. All dogs were administered 4 sequential weekly subcutaneous injections of pentosan polysulfate (3 mg/kg; Cartrophen Vett, Arthropharm (Europe) Ltd., Portadown, Northern Ireland) unless this had been administered immediately before referral, otherwise administration started 2 weeks

Surgical Technique After arthroscopic examination, elbows with MCD were treated by SCO performed through a ‘‘mini-arthrotomy’’ by a single surgeon (N.F.). If MCD was diagnosed bilaterally, SCO was performed on both elbows in a single session. A 2 cm skin incision was made to enlarge the arthroscope portal over the craniomedial aspect of the humeral condyle and subcutaneous tissues were sharply dissected. Blunt separation of the flexor carpi radialis/pronator teres and the superficial/deep digital flexor muscles caudal to the medial collateral ligament allowed access to, and sharp incision of, the medial joint capsule proximal to the fan-shaped insertion of the biceps brachii muscle on the MCP using a #11 scalpel blade. The use of 2–4 Gelpi self-retaining retractors positioned caudal to the medial collateral ligament maximized exposure of the medial joint compartment and facilitated SCO.

Fig 1. Schematic representation of line of SCO (green line) relative to the typical location of radial incisure fragmentation (red line).


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postoperatively, at the time of suture removal. Cage confinement (6 weeks) and leash-restricted exercise (12 weeks) were requested. Dogs that did not experience resolution of visible lameness by 6–12 weeks were managed by extended periods of cage restriction and/or leash-restricted exercise and continuation of nonsteroidal antiinflammatory (NSAID) medication. Variation in postoperative management included use of hydrotherapy and physiotherapy. Hydrotherapy was prohibited for all dogs until 8 weeks. Lifetime administration of a daily nutraceutical containing chondroitin sulfate and glucosamine (Synoquint, VetPlus Ltd., Lytham, UK) was recommended in accordance with the manufacturer’s dosage guidelines.

Outcome Measures Short Term. Clinical examination including subjective assessments of lameness and pain on elbow manipulation, by a single investigator (N.F., J.R., or R.Y.), was performed at 2 and 5 weeks in all dogs, and thereafter at 4–5 week intervals if lameness persisted. All owners were asked to report if lameness recurred at any time after resumption of normal activity at 12 weeks, whereupon reexaminations were scheduled. Long Term. All dogs were asked to return for follow-up examinations between 1 and 7 years after surgery. Examinations included: (1) Owner questionnaire (Appendix 1) examined subjective owner assessments of: commonly performed daily activities using visual analog scales (VAS); postoperative lameness history; current level of lameness; current medication requirements; and overall outcome. The occurrence of any surgical treatment of the thoracic limb after SCO was noted and resulted in study exclusion. (2) Clinical evaluation performed by a single investigator (N.F., T.S., J.R., or R.Y.) using a standardized questionnaire (Appendix 2) allowed: subjective assessment of gait evaluation at a walk, trot and run graded as 0–5; and pain response to elbow extension, flexion and flexion with simultaneous pronation or supination of the ante-brachium recorded on a VAS. (3) Subjective assessment of gait using video images of dogs: walking towards, away and sideways (left- and right-sided views); and a single trot towards the camera. These video clips were edited into single movies and assessed by 7 independent Diplomates of the American College of Veterinary Surgeons (ACVS). Each assessor was unaware of the clinical history and current medication, but was aware that each dog had undergone SCO for MCD of 1 or both thoracic limbs within the last 6 years. Gait evaluation was graded as 0–5. Dogs administered antiinflammatory medication were subsequently excluded from statistical analysis. (4) Assessment of osteophytosis. Radiographic examination under sedation included mediolateral flexed and craniocaudal projections of both elbows. Presence of elbow osteophytosis was graded 0–3 by one investigator (T.S.).

Statistical Analysis Descriptive statistics were calculated for preoperative and follow-up data including breed, sex, age, duration of lameness/ limb, radiographic findings, arthroscopic findings, length of time to resolution of lameness, medication use, recurrence of lameness, time to follow-up, and veterinary and owner assessments of gait. VAS were determined by the position of a mark placed by the owner along a 100 mm line, measured to the nearest mm using a ruler. A value of 0 represented poor outcome; a value of 100 represented excellent outcome. Descriptive statistics were calculated for VAS and pre- and postoperative scores for each function were compared by paired t-test. The level of interobserver agreement between ACVS investigator assessments of gaits was calculated using the kappa statistic. The median value-assessing gait for each dog was listed. The progression of osteophytosis was summarized by numbers of elbows (and relative percentages) per grade of osteophytosis. Software (JMP version 6.0.0 software; SAS Institute, Cary, NC) was used for statistical analysis; confidence interval was set at 95%.

RESULTS Two hundred and sixty-three dogs (437 elbows) met the study criteria. Signalment Median dog age at surgery was 14 months (mean, 32 months; range, 4–135 months). Thirty-eight breeds were represented, the most frequent being Labrador retrievers (132 dogs, 50%), Rottweilers (32 dogs, 12%) and Golden Retrievers (13 dogs, 5%). Male: female ratio was 5:3 with 49 (18.6%) intact and 48 (18.3%) neutered females, and 100 (38.0%) intact and 66 (25.1%) neutered males. Preoperative Gait Evaluation Sixty-five percent of dogs were admitted for investigation of unilateral thoracic limb lameness. Of these dogs, clinical examination identified bilateral lameness in 66%. Mean  SD lameness duration before SCO/elbow was 14.5  14.20 weeks (median, 12 weeks; range, 1–108 weeks; 272 elbows). Preoperative Radiographic and Arthroscopic Findings Radiographic findings included subtrochlear sclerosis of the proximal ulna and osteophytosis of the radial head, anconeal process, and humeral condyle. Median osteophytosis grade was 1 (range, 0–3; Table 1). Arthroscopic findings included synovitis, synovial proliferation, cartilage lesions of the MCP and medial aspect of the humeral condyle, fissuring and fragmentation of


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FITZPATRICK ET AL Table 1. Osteophytosis Grades Preoperatively and at 1–5 year Follow-Up

Time of Evaluation Preoperative 1 year Follow-up 2 year 3–5 years Total

Osteophytosis Grade

Number of Elbows Assessed (%)

0

1

2

3

423 76

122 (28.8%) 6 (7.9%)

138 (32.6%) 12 (15.8%)

121 (28.6%) 31 (40.1%)

42 (9.9%) 26 (34.2%)

32 72 180 (100%)

3 (9.4%) 3 (4.2%) 12 (6.7%)

4 (12.5%) 7 (9.7%) 23 (12.8%)

12 (37.5%) 28 (37.5%) 71 (39.4%)

13 (40.7%) 34 (47.2%) 73 (40.6%)

the bone of the MCP. Median modified Outerbridge score for MCP cartilage was 2 (range, 0–5) and for the medial aspect of the humeral condyle was 0 (range, 0–5). The MCP was grossly intact in 77 (17.6%), fissured in 80 (18.3%) and fragmented in 280 (64.1%) elbows. SCO was bilateral in 174 dogs (66.2%) and unilateral in 89 (33.8%) dogs. Surgical Technique and Perioperative Complications SCO was performed in the first 38 elbows using an osteotome and mallet, and in the next 399 elbows using an oscillating saw. A single intraoperative complication occurred in 1 of the 38 elbows that had SCO by using an osteotome and mallet. During osteotomy, a fissure propagated partially through the distal ulnar notch. This was stabilized by insertion of a 2.0 mm cortical position screw. Short Term Outcome Veterinary Assessment. Postoperative complications in the immediate postoperative period occurred in 36 of 437 elbows (8.2%). These were septic arthritis (30 elbows), seroma (3), swelling (2), and wound dehiscence (1). Improvement in subjectively assessed lameness after SCO to a score of 0 was recorded at 5 weeks in 324 of 437 (74.4%) of elbows and at 12 weeks in 91.2% (397 elbows). Twenty-two elbows (5.1%) remained lame after SCO (Table 2); 7 (1.9%) of these had persistent lameness that could not be successfully managed to an acceptable level by continued NSAID administration and exercise modulation. Long Term Outcome Veterinary Assessment. Ninety dogs (34.2%) had a median follow-up of 1 year 7 months (range, 4 months to 5 years 6 months). Median lameness score/thoracic

limb was 0 (range, 0–4; 171 elbows). Mean assessment of function was considered close to normality (0.0 mm) with mean scores of 9.2 mm (walk), 8.3 mm (trot), and 4.7 mm (run). Mean assessment of pain on elbow flexion, extension, internal, and external rotation was considered close to normality, with mean scores of 6.1, 0.8, 8.9, and 10.6 mm, respectively (Table 3). Radiographic Assessment. Median dog age at followup radiographic examination was 2 years 6 months (range, 1 year to 7 years 7 months). Radiographic examination was available for 180/437 (41.2%) of elbows with median follow-up of 1 year 5 months (range, 9 months to 5 years 6 months). Of these, 12/180 (6.7%) of elbows remained free from osteophytosis compared with 122/423 (28.8%) preoperatively. Median osteophytosis score was 1 (range, 0–3; Table 1). Median increase in osteophytosis score was 1 grade compared with preoperative scores. Owner Questionnaire Assessment. Owner assessment was available for 146/263 (55.5%) of dogs (median age, 3 years 2 months; range, 1 year 2 months to 14 year 9 months) and a median follow-up of 1 year 8 months (range, 4 months to 5 years 6 months). Owner assessment of lameness resolution was available for 287/437 thoracic limbs (65.7% of all elbows treated). Owners assessed 236/ 287 (82.2%) thoracic limbs remained sound but lameness returned in 51/287 (17.8%). Lameness was noted: immediately in 4 (1.5%) limbs; by 12 weeks in 8 (2.8%); by 6 months, in 38 (13.5%); and after 6 months in 39 (13.6%). Of the 139 owner responses, 23 (16.5%) dogs received NSAID medication and 83 (59.7%) received nutraceutical supplementation (Table 4). Owner-assessed VAS function scores revealed significant improvement from preoperative impression to follow-up assessment for each question (Fig 2). Lameness assessment at follow-up was available for 289 thoracic limbs (67.4% elbows treated) and was considered:

Table 2. Veterinary and Owner Assessment of Lameness after SCO Number of Elbows (%) Free from Lameness at a Walk (Cumulative % in Bold)

Assessment Method

Elbows

2 weeks

5 weeks

12 weeks

24 weeks

Never

Owner Veterinarian

287 435

61 (21.3%) (21.3%) 189 (43.4%) (43.4%)

70 (24.3%) (45.6%) 135 (31.0%) (74.4%)

74 (25.8%) (71.5%) 73 (16.8%) (91.2%)

61 (21.3%) (92.7%) 16 (3.7%) (94.9%)

21 (7.3%) (100.0%) 22 (5.1%) (100.0%)


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SUBTOTAL CORONOID OSTECTOMY

DISCUSSION

Table 3. Veterinary Assessments at 1–5 year Follow-Up Examination Function Walk Trot Run

Elbows

Mean  SD (mm)

Median, (Range) mm

168 166 154

9.2  11.9 8.3  13.6 4.7  13.0

5.5 (0–73) 0.0 (0–90) 0.0 (0–60)

never ¼ 163 (56.4%), rarely ¼ 40 (13.8%), sometimes ¼ 44 (15.2%), most of the time ¼ 8 (2.8%), lameness evident immediately after heavy exercise ¼ 22 (7.6%), and always ¼ 12 (4.1%). Owner assessment of the success of SCO, their dog’s current quality of life, and whether they would have SCO performed again was in general very favorable (Table 5). Subjective Assessment of Gait Median dog age at gait analysis was 3 years 3 months (range, 1 year 8 months to 7 years 7 months). Gait assessment was available for 110 of 437 (25.2%) elbows with a median follow-up of 1 year 8 months (range, 10 months to 3 year 5 months). Median lameness score/ elbow, calculated by taking the median from the range of scores made by 6 observers, was 0 (range, 0–2; Table 3). Of these, 69/110 (62.7%) thoracic limbs were had improvement in lameness to a score of 0 (Table 6). The kappa statistic for interobserver agreement between assessors of gait was considered low, ranging from 0.01 to 0.20.

SCO, cage rest refinement, and parenteral administration of pentosan polysulfate were used to manage thoracic limb lameness attributed solely to MCD in 437 elbows. Our technique for SCO was associated with a low (1 elbow) intraoperative and immediate postoperative complication rate (8.2% elbows, of which, 7.0% were septic arthritis). Improvement in lameness to a score of 0 occurred in 71.3% (veterinary assessment) and 92.2% (owner) by 12 weeks, and 92.4% (veterinary) and 95.9% (owner) by 24 weeks. Follow-up owner assessment questionnaires revealed that most treated limbs (82.2%) remained sound in the long-term and of these 16.5% were being managed by oral NSAID. Subjective gait assessment from video recording yielded that 62.7% of treated limbs remained sound in the medium term; none were being managed by NSAID administration. Veterinary assessment of lameness and of pain evident on elbow manipulation, while subjective, indicated a favorable outcome. Based on these findings, we recommend consideration of SCO and postoperative management for treatment of MCD. Diagnosis of MCD We based diagnosis of MCD on a combination of findings: (1) physical examination demonstrating presence of thoracic limb lameness associated with pain on elbow manipulation; (2) radiographic findings of periarticular

VAS Score (mm)

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50

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* p<0.05

Fig 2. Box plot showing owner assessment of commonly performed daily functions. Preoperative assessments (white bars) and assessments at the time of owner questionnaire (grey bars). A statistically significant difference, for all functions assessed, was shown between preoperative and follow-up assessments (Po.05).


239

FITZPATRICK ET AL Table 4. Medication Usage at Time of Owner Questionnaire Examination Medication

Number of Dogs (%)

None NSAID NSAID þ nutraceuticals NSAID þ pentosan polysulfate Nutraceutical Nutraceutical þ pentosan polysulfate Total

45 10 12 1 67 4 139

(32.4) (7.2) (8.6) (0.7) (48.2) (2.9) (100)

osteophytosis; and (3) arthroscopic findings of fragmentation, fissuring or edge margin fibrillation of the MCP and cartilage malacia of the surface of the MCP and/or synovitis. Use of SCO for management of MCD in elbows where the only pathology was ‘‘low-grade’’ cartilage lesions may be considered aggressive. In our opinion, thoracic limb lameness localized to the elbow joint without other overt elbow pathology (e.g., ununited anconeal process, osteochondrosis, or incomplete ossification of the humeral condyle) but with presence of low-grade cartilage disease of the MCP should be attributed to and classified as MCD. The decision to surgically intervene is controversial because there are no reports documenting the fate of elbows with grossly intact MCP affected by clinical signs of MCD. Management of such cases is challenging and has not been addressed in published reports. SCO is a potential approach for managing such cases. There are no reports of outcome after surgical intervention for MCD where the MCP was grossly ‘‘intact’’ on arthroscopic evaluation, although a recent report anecdotally described surgical intervention on the basis of CT findings in the absence of overt arthroscopic pathology.18

Table 6. Median Lameness Scores Determined by Subjective Assessment Median Lameness Score per Elbow 0 1 2 3 4 5 Total

Elbow Number (%) 69 30 11 0 0 0 110

(62.7) (27.3) (10.0) (0.0) (0.0) (0.0) (100)

cartilage, and most diseased subchondral bone. Histomorphometry of excised portions of the MCP collected from dogs in our study revealed presence of pervasive subchondral microcracks22 which supports the theoretical advantage of removing a larger portion of the MCP than that identified as grossly diseased by arthroscopic or CT examination. However, clinical outcomes measures are critical to support application of this hypothesis. The mechanism by which such overload could occur may involve primary osseous static or dynamic incongruity,23,24 such as disparity in radioulnar growth, misshapen ulnar trochlear notch, or divergence of the radioulnar joint surfaces during pronation or supination which may expose the MCP to excessive mechanical load. Secondary biomechanical effects involving periarticular musculotendinous forces such as a mismatch in development of osseous and musculotendinous tissues may also contribute to excessive loading of the MCP. It is possible that treatment of MCD by SCO may ameliorate the effects of this load aberration, but further biomechanical data would be required to validate this concept. Potential Disadvantages of SCO

Rationale for SCO We reasoned that SCO would remove a standardized portion of the MCP that included all fragments, diseased Table 5. Owner Assessment of the Success of SCO, Quality of Life and Whether They Would have SCO Performed Again, Assessed on VAS Scores VAS Score Assessment Description Success of SCO Quality of life at assessment Have SCO performed again

Number of Owners

Mean  SD. (mm)

Median, (Range) mm

140 142

82  24.8 77  26.9

93 (0–100) 90 (1–100)

127

88  20.6

96 (0–100)

Scores of 0 mm represents a very poor outcome, 100 mm represents an excellent outcome.

More aggressive ostectomy of a larger portion of the medial ulnar joint contact area could theoretically result in load redistribution to either the remaining portion of the medial contact area, or to the lateral elbow contact area including the radial head. Focally increased loading stresses could potentially accelerate cartilage degeneration or cause subchondral pathology at these sites. The use of further imaging modalities like arthroscopic or histologic measures at long-term follow-up would be required to establish the development of such changes and their clinical significance. Destabilization of the elbow joint by the surgical approach for SCO represents a further theoretical disadvantage and could occur by disturbance of periarticular structures including the joint capsule (which may be continuous with the medial collateral ligament), the tendon of insertion of the biceps brachii muscle, or the annular ligament. It is improbable that resultant effects would pose a significant clinical


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SUBTOTAL CORONOID OSTECTOMY

problem and overt instability was not recorded as a finding in our dogs. Other disadvantages may be associated with creation of the ostectomy. In a single elbow, fissuring of the proximal aspect of the ulna occurred during ostectomy with an osteotome, and although this has not occurred again, it should be considered as a potential hazard with this surgical technique. Infection rate (7.0%) was higher than might be anticipated for diagnostic elbow arthroscopy alone (reported as 0%25), although complication rates specific to arthroscopic treatment of coronoid disease have not been published. Whereas the high rate of infection may partially be artifactual because it included dogs with positive bacterial culture of synovial fluid or tissue and also dogs with effusion and lameness postoperatively that responded to antibiotic therapy in the absence of positive bacterial culture. Our infection rate was comparable to the 7.1% described for other clean canine orthopedic procedures26; however, the possibility of increased infection rate over alternative techniques cannot be excluded, and could potentially be attributed to generation of bone debris or excessive focal heat generation during ostectomy using an oscillating saw blade. Lameness Preoperative duration of lameness varied (median, 12 weeks). All dogs had single or multiple unsuccessful periods of medical management and exercise restriction before surgical intervention. Variability likely reflected the insidious intermittent nature of the lameness, primary care treatment regimes, owner willingness for referral, and variations in owner perception of the onset of lameness. Many dogs were referred for investigation of putative shoulder lameness. All dogs that had pathology confirmed arthroscopically had evident pain (vocalization or marked resentment) when deep, digital pressure was applied to the medial aspect of the elbow or when the elbow was manipulated in flexion-supination. Documented improvement in lameness to a score of 0 after SCO may be at least be partially attributable to: (1) the postoperative management techniques, including exercise restriction (cage confinement, leash restriction) and medical management (pentosan polysulfate, NSAID, nutraceuticals); and (2) the incidence of bilateral MCD managed by bilateral SCO resulting in bilateral lameness that could not be appreciated by the subjective assessment methods used. The administration of a course of 4 injections of pentosan polysulfate during the immediate postoperative period may have contributed to clinical improvement27 seen during this phase of recovery, but was considered unlikely to have had any sustained confounding effect on long-term outcome. The postoperative management approach we used dictated that the earliest

possible return to ‘‘normal function’’ was 12 weeks because off leash exercise was not permitted before then. Subjectively, most dogs admitted with lameness or pain on manipulation within the first 24 weeks were associated with poor owner or dog compliance with our recommended management protocol in the initial 12 weeks. Loss of Dogs to Follow-Up Frustratingly, most dogs lost to follow-up were because of owner unwillingness to participate in re-examination. Two potential explanations are that dogs failed to respond to SCO and owners chose not to continue with the study (falsely elevating the results), or that the response to SCO was favorable and owners could see no benefit to their dog in further examinations (falsely reducing the reported results). We considered it likely that the reasons dogs were not reexamined occurred randomly among these potential explanations so that conclusions based on the collected data fairly reflect those applicable to the treatment population. Use of a standard questionnaire across all dogs may fail to provide optimal evaluation of individual dogs. Whereas client specific outcome measures may provide more detailed data for an individual dog, they were not used because of an inability to draw meaningful conclusions across a larger patient population. Long Term Complications Aside from progression of OA, long-term (up to 7 years 7 months) complications have not been observed. Adverse sequelae, including lateralization of the elbow because of medial compartment collapse, have not been diagnosed in any of our dogs. Documented progression of radiographic indicators of OA in the long-term is consistent with other reports (Table 7).2 It has been reported that gene expression may play an important role in determining severity of radiographic changes in canine elbow OA.28 Associations between radiographic and histologic measures of OA have not been well characterized.

Table 7. Comparison of Follow-Up Radiographic Scoring of Osteophytosis between Arthrotomy and Arthroscopy Reported by Meyer-Lindenberg et al2 and SCO Degree of osteophytosis at follow-up examination Surgical Method Arthrotomy2 Arthroscopy2 SCO via mini-arthrotomy

0

1

2

3

Total

2 (1.9) 3 (2.2) 7 (4.4)

24 (23.3) 44 (32.6) 17 (10.8)

36 (35.0) 43 (31.9) 63 (40.1)

41 (39.8) 45 (33.3) 70 (44.6)

103 (100) 135 (100) 157 (100)


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Study Limitations Absence of a control or cohort group is an important limitation. Our study differs from recent reports because it was prospective, enrolling cases with lameness solely attributable to MCD, and because a standardized portion of the MCP was removed regardless of the degree of MCD observed on arthroscopic examination. Our findings are therefore difficult to directly compare with previous reports, especially studies that fail to distinguish different forms of elbow dysplasia in their treatment populations9,10,13,29; used various focal treatment options for the MCP; or used a more aggressive arthrotomy technique. Compared with treatment via arthrotomy, arthroscopic treatment of MCD may yield superior outcomes.2,20 The mini arthrotomy technique we used is a modification of conventional techniques and involved simple extension of the arthroscopy portal to allow access for instrumentation and ensure reproducibility of osteotomy position. Though only a single case of iatrogenic fracture occurred, this remains a potential risk when performing SCO using an osteotome. Based on subsequent experience, we recommend use of an oscillating saw for SCO to ensure consistent results. Removal of a portion of the MCP by arthroscopically guided osteotome or motorized shaver has been reported with a similar goal of reducing abrasion and obviating requirement for cartilage healing in a pressure contact environment.19 We would expect that the results of arthroscopically assisted SCO would be similar, or superior, to SCO via mini arthrotomy based on the potential advantages of arthroscopic surgery. Absence of objective outcome measures is a salient limitation of this and other previously published clinical studies. Assessment of pain on elbow manipulation or visual gait assessment are intrinsically subjective, but have nevertheless been included as pre- and postoperative analysis variables in our study because we felt it important to include data most readily applicable to the clinical environment where kinetic or kinematic assessments are not typically available. Clinical variables remain valid in the absence of more objective means of lameness interrogation. All of our examinations were conducted by experienced clinicians and we feel that it is difficult to justify arthroscopic inspection of the elbow in a clinically lame dog without documenting the degree of perceived lameness and without clinical examination indicating elbow pain. We therefore considered it valid to include and attempt to standardize these preoperative examinations and to compare similar examinations over time. So although these are subjective measures they were compared using the same pre- and postoperative criteria. The subjective nature of visual lameness assessment was

illustrated by poor interobserver correlation of gait assessment from video recordings. Nevertheless, observers were unaware of the clinical history of individual dogs and median values for lameness were low providing evidence of treatment efficacy. From the owners’ perspective, most (82.2%) of thoracic limbs were free from visible lameness at follow-up, with only 4.1% being permanently lame, resulting in a high level of client satisfaction at long-term follow-up. However, this included 16.5% of dogs that were receiving NSAID medication. The effect of nutraceuticals on outcome measures after SCO remains unknown, primarily because of a lack of consensus about the efficacy of nutraceuticals for treatment of OA in dogs. We consider that nutraceutical administration was unlikely to have negatively influenced our results. Our protocol for treatment of MCD included removal of a standardized portion of the MCP through a mini arthrotomy, exercise restriction, and administration of pentosan polysulfate, was associated with minimal perioperative morbidity, and warrants consideration for treatment of MCD, even when gross fissuring and fragmentation of the MCP is not evident. This treatment approach led to the resolution of lameness in the short- and long-term in most affected dogs regardless of the initial degree of gross pathology, and to remission of clinical signs in the long-term. Comparison of this technique with other commonly used methods of treating MCD using objective outcome assessments is warranted.

ACKNOWLEDGMENTS We thank all owners who enrolled their dogs in this study; the referring veterinary surgeons; Tim Vojt for Fig 1; Drs James Cook, Michael Kowaleski, Wayne Whitney, Kurt Schulz, Don Hulse, Matthew Rooney and Chad Devitt for their valuable time performing the subjective assessment of gait on video recordings; and Karen Bailey for her assistance arranging follow-up appointments.

REFERENCES 1. Meyer-Lindenberg A, Langhann A, Fehr M, et al: Prevalence of fragmented medial coronoid process of the ulna in lame adult dogs. Vet Rec 151:230–234, 2002 2. Meyer-lindenberg A, Longhann A, Fehr M, et al: Arthrotomy versus arthroscopy in the treatment of the fragmented medial coronoid process of the ulna (FMCP) in 421 dogs. Vet Comp Orthop Traumatol 16:204–210, 2003 3. Kirberger RM, Fourie SL: Elbow dysplasia in the dog: pathophysiology, diagnosis and control. J South Afr Vet Assoc 69:43–54, 1998


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4. Ness MG: Treatment of fragmented coronoid process in young dogs by proximal ulnar osteotomy. J Small Anim Pract 39:15–18, 1998 5. Collins KE, Cross AR, Lewis DD, et al: Comparison of the radius of curvature of the ulnar trochlear notch of Rottweilers and Greyhounds. Am J Vet Res 62:968–973, 2001 6. Puccio M, Marino DJ, Stefanacci JD, et al: Clinical evaluation and long term follow up of dogs with coronoidectomy for elbow incongruity. J Am Anim Hosp Assoc 39:473–478, 2003 7. Read RA, Armstrong SJ, O’Keef D, et al: Fragmentation of the medial coronoid process of the ulna in dogs: a study of 109 cases. J Small Anim Pract 31:330–334, 1990 8. Huibregtse BA, Johnson AL, Muhlbauer MC, et al: The effect of treatment of fragmented coronoid process on the development of osteoarthritis of the elbow. J Am Anim Hosp Assoc 30:190–195, 1994 9. Bouck GR, Miller CW, Taves CL: A comparison of surgical and medical treatment of fragmented coronoid process and osteochondritis dissecans of the canine elbow. Vet Comp Orthop Traumatol 8:177–183, 1995 10. Grondalen J: Arthrosis in the elbow joint of young rapidly growing dogs. I. Ununited medial coronoid process of the ulna and osteochondritis dissecans of the humeral condyle. Nord Veterinaermed 31:520–527, 1979 11. Grondalen J: Arthrosis with special reference to the elbow joint of rapidly growing dogs. II. Occurrence, clinical and radiographic findings. Nord Veterinaermed 31:69–75, 1979 12. Bennett D, Duff SRI, Kene RO, et al: Osteochondritis dissecans and fragmentation of the coronoid process in the elbow joint of the dog. Vet Rec 109:329–336, 1981 13. Boudrieau RJ, Hohn RB, Bardet JF.: Osteochondrosis dissecans of the elbow in the dog. J Am Anim Hosp Assoc 19:627–635, 1983 14. Henry WB: Radiographic diagnosis and surgical management of fragmented medial coronoid process in dogs. J Am Vet Med Assoc 184:799–805, 1984 15. Tobias TA, Miyabayashi T, Olmstead ML, et al: Surgical removal of fragmented medial coronoid process in the dog: comparative effects of surgical approach and age at time of surgery. J Am Anim Hosp Assoc 30:360–368, 1994 16. Schulz KS, Mason DR, Samii VF, et al: Sensitivity of radiography to radioulnar incongruence in the dog. Proceedings of the 10th Annual Symposium of the American College of Veterinary Surgeons, Arlington, VA, 2000, p 20

17. Moores AP, Benigni L, Lamb CR: Computed tomography versus arthroscopy for detection of canine elbow dysplasia lesions. Vet Surg 37:390–398, 2008 18. Van Ryssen B: Arthroscopic findings in elbow incongruity. Proceedings of the 1st International Meeting of Arthroscopy Working Group of ESVOT, Munich, Germany, October 2003. 19. Holsworth I: The role of sub-total arthroscopic partial coronoidectomy and concurrent distal ulnar ostectomy. Proceedings of the British Veterinary Orthopaedic Association Autumn Scientific Meeting, Birmingham, UK, November 2006, p 30 20. Evans RB, Gordon-Evans WJ, Conzemius MG: Comparison of three methods for the management of fragmented medial coronoid process in the dog. Vet Comp Orthop Traumatol 21:106–109, 2008 21. Schulz KS: What’s new in elbow arthroscopy? Proceedings of the 13th Annual American College of Veterinary Surgeons Symposium, Washington DC, October 2003. 22. Danielson KC, Fitzpatrick N, Muir P, et al: Histomorphometry of fragmented medial coronoid process in the dog: a comparison of affected and normal coronoid processes. Vet Surg 35:501–509, 2006 23. Wind AP, Packard ME: Elbow incongruity and developmental elbow diseases in the dog. Part II. J Am Anim Hosp Assoc 22:725–730, 1986 24. Lozier SM: How I treat elbows in the older canine patient and new perspectives in elbow dysplasia. Proceedings of the 13th European Society of Veterinary Orthopaedic Traumatology Congress, Munich, Germany, September 7–10, 2006, pp 93–96. 25. Van Ryssen B, van Bree H: Arthroscopic findings in 100 dogs with elbow lameness. Vet Record 140:360–362, 1997 26. Whittem T, Johnson A, Smith C, et al: Effect of perioperative prophylactic antimicrobial treatment in dogs undergoing elective orthopedic surgery. J Am Vet Med Assoc 215:212– 216, 1999 27. Read RA, Cullin-Hill D, Jones MP: Systemic use of pentosan polysulphate in the treatment of osteoarthritis. J Small Anim Pract 37:108–114, 1996 28. Clements DN, Fitzpatrick N, Carter SD, et al: Cartilage gene expression correlates with radiographic severity of canine elbow osteoarthritis. Vet J, 2007 (e-pub ahead of print), October 29. Mason TA, Lavelle RB, Skipper SC, et al: Osteochondrosis of the elbow joint in young dogs. J Small Anim Pract 21:641–656, 1980


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Appendix 1 Owner follow-up questionnaire Surname:…………………….Animal Name:……………..

Date: ....../……/……

Has your dog had any leg operations since his/her elbow surgery? …YES / NO (please circle) If so please specify…………………………………………………………………… Is your dog currently on any medication, if so please specify drugs and doses:………………………………………………………………………………… ……………………………………………………………………………………………………………………… ……………………………………………. Please circle the answer that is most correct: (please answer questions for both front legs regardless of whether a fragment was removed). When did the lameness resolve relative to the surgery? Left leg

By2 weeks

By 5 weeks

By 12 weeks

By 6 months

Never

Can’t remember

Right leg

By2 weeks

By 5 weeks

By 12 weeks

By 6 months

Never

Can’t remember

Have you noticed the limp return at any time after surgery? Left leg

Never

After 6 months

After 1 year

After 2 years

Right leg

Never

After 6 months

After 1 year

After 2 years

Is your dog ever lame now? Left leg

Never

Rarely

Sometimes

Most of the time

Always

Following heavy exercise

Right leg

Never

Rarely

Sometimes

Most of the time

Always

Following heavy exercise


244

SUBTOTAL CORONOID OSTECTOMY Please answer the following questions by marking on the line how well or poorly your pet can perform each of the following. Mark an ‘O’ to indicate before operation and a ‘X’ to indicate levels now: Example: How well can your dog climb up

Poorly

O

X

Very well

stairs? How well can your dog walk without pain?

Painful

Not painful

Poorly

Very well

Poorly

Very well

Poorly

Very well

Poorly

Very well

How well can your dog climb UP stairs? How well can your dog climb DOWN stairs? How well can your dog jump up (for example, into the car)? How well can your dog jump down (for example, out of the car)?

What is your dog’s exercise tolerance

Struggles on short

(ability to go for walks comfortably)?

walks

Copes fine with long walks

How well can your dog sit down without pain or hesitation?

Poorly

Very well

Poorly

Very well

Poorly

Very well

Poorly

Very well

How well can your dog lie down without pain or hesitation? How well can your dog rise on front legs without pain or hesitation? How well can your dog rise on hind legs without pain or hesitation? Would you say your dog can run normally?

Totally abnormal

Completely normal

Does your dog nod his/her head during exercise?

Lots

Not at all

Poor

Excellent

How would you grade the success of the operation? In your opinion does your dog have any restriction of his/her quality of

Very restricted

No restriction at all

life due to forelimb lameness problems? Would you have this operation done Never again in the same circumstances?

Definitely

Any further comments:…………………………………………………………………………………………………………...............................


245

FITZPATRICK ET AL Appendix 2 Veterinary follow-up questionnaire Surname……………………Animal Name:……………..

Date:....../……/……Clinician………..

Weight________ kg Please circle the answer which is most correct: (please answer questions for both front legs regardless of whether a fragment was removed ) •

Lameness score:

LFL

0

1

2

3

4

5

RFL

0

1

2

3

4

5

LHL

0

1

2

3

4

5

RHL

0

1

2

3

4

5

Please indicate left and right legs with a ‘L’ or ‘R’ on the scale:

Example:

Low

L

R

High

Function at

Totally

Totally

walk

normal

abnormal

Function at

Totally

Totally

trot

normal

abnormal

Function at

Totally

Totally

run

normal

abnormal

Flexion (pain)

None

Severe

None

Severe

None

Severe

None

Severe

Extension(pain)

Internal rotation / supination (pain) External rotation / pronation (pain)

Any further comments:…………………………………………………………………………………………………………..


Subtotal Coronoid Ostectomy for Treatment of Medial Coronoid