Clinical Evaluation of a Novel Technique of Impacting Osteochondral Grafts: Center-Hole Technique vs. Standard Impaction Ben B. Bedford, MD, Aruna M. Seneviratne, MD, Stephen J. Nicholas, MD Nicholas Institute of Sports Medicine and Athletic Trauma (NISMAT), Lenox Hill Hospital, New York Methods
Introduction Osteochondral autograft and allograft transplantation is an accepted treatment strategy for chondral and osteochondral defects of the knee and shoulder. The purpose of this study was to retrospectively review the clinical outcome and graft morphology in patients with symptomatic osteochondral lesions treated with osteochondral transplantation. Hypothesis: The novel center-hole technique for graft impaction will lead to similar clinical outcomes and will potentially protect articular cartilage by promoting chondrocyte viability.
Threshold for chondrocyte apoptosis
Between 2006 and 2009 five patients with symptomatic chondral or osteochondral defects (four knees, one shoulder) were treated with either autologous osteochondral transplantation (two) or osteochondral allograft transplantation (three). The grafts were press-fit using either standard impaction or the center-hole technique. Frozen allograft plugs were used to backfill the autograft donor site in two knees. Mean age at the time of surgery was thirty-one years. The mean lesion size was 312 mm2. Clinical assessment was performed postoperatively using the International Knee Documentation Committee (IKDC) score, activity of daily living of the Knee Outcome Survey (ADL) score, and Short Form-36 (SF-36) at most recent follow-up. Magnetic resonance imaging was used to evaluate the morphologic and signal characteristics of the implanted grafts and the surrounding cartilage. Standard statistical methods using a paired Student’s t-test were used to analyze the data.
Distribution of Force
Five patients met the study criteria with a mean duration of follow-up of 15.6 months (range, four to thirty-one months). The mean preoperative IKDC score was 61.2 ± 17.5 and improved to 77.3 ± 22.3 (p= .016). The mean preoperative ADL score was 73 ± 9.3 and improved to 88.5 ± 10.3 (p=.008). The mean SF36 score also improved from 83.4 ± 4.6 to 90.7 ± 5.9 (p=.013). At a mean follow-up of 15.8 months cartilage sensitive MRI demonstrated a flush plug appearance in all patients and osseous trabecular incorporation in 75% of patients. The graft cartilage had preserved thickness and was isointense to surrounding cartilage in all patients. With the exception of increased temporary bone edema in 50% of patients, the graft properties were similar in those press-fit with the center-hole technique to those treated with standard impaction.
Conclusions Osteochondral transplantation is an effective treatment for osteochondral defects in the knee and shoulder. In our series there was a significant improvement in all three mean clinical outcome scores. MRI can be a valuable tool for postoperative evaluation of graft cartilage and osteointegration. On MRI the centerhole technique led to increased signal within the bone. This resolved on subsequent MRI and may not have any important clinical significance. From a technical standpoint, this technique allows greater control of the graft during insertion. Center-hole technique is a viable alternative to standard impaction resulting in similar clinical outcome scores, while potentially improving long term graft survival due to increased chondrocyte viability at the time of implantation.
MRI T2 Mapping Assess Collagen Orientation Orange = Short T2 values (collagen perpendicular to subchondral plate) Yellow = Longer T2 values (more random collagen orientation) Correlates with polarized light microscopy
Acknowledgments Center Hole
Live/Dead Staining of In-Vitro section of Hyaline Cartilage Red = Dead Chondrocytes Green = Live Chondrocytes Standard Technique
Center Hole Technique
Screw is placed in center of graft Then impacted into recipient site Screw removed
Dr. Michael Vazquez
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