Conversion of unicompartmental knee arthroplasty to total knee arthroplasty: the challenges and need for augments.

The potential advantages of unicompartmental knee arthroplasty (UKA) include lower morbidity and mortality, quicker recovery, good range of motion, good medium and long-term survival results, potential bone conservation and perceived easier revision. Converting a UKA to a total knee arthroplasty (TKA) may be challenging due to issues of bone loss, need for augmentation, restoring joint line and rotation. We present the intraoperative findings of 201 cases of failed UKA's from the Trent Wales arthroplasty audit group (TWAAG) register. The objectives of the study were to determine the modes of failure, number of cases requiring augments and bone grafting, types of augments and implants used in revision surgery. This study does not include the clinical outcomes after revision knee surgery. The average age of the cohort at revision surgery was 67 years. There were 111 females and 90 males. The commonest modes of failure in young patients were unexplained pain/instability and aseptic loosening and in older patients they were aseptic loosening and progression of the disease. The survivorship of the implant was higher in the less than 55 years age group in comparison to the older patients. A total of 49 patients (25.9%) required bone grafting commonest in the 60 years and above age group (79.6%). Fifty patients (26.4%) required some form of augmentation, with the commonest site being tibia and commonest augment being tibial stem (35 cases). Only 8% of the cohort required revision knee implants whereas 78% of the cases received a cruciate retaining primary knee implant. To the author's knowledge, this is one of the largest studies in the literature which signifies the technical difficulties that might be experienced in revising the UKA's which will require appropriate pre-operative planning.

Outcome of combined autologous chondrocyte implantation and anterior cruciate ligament reconstruction.

BACKGROUND: Instability of the knee joint, after anterior cruciate ligament (ACL) injury, is contraindication to osteochondral defect repair. This prospective study is to investigate the role of combined autologous chondrocyte implantation (ACI) with ACL reconstruction. MATERIALS AND METHODS: Three independent groups of patients with previous ACL injuries undergoing ACI were identified and prospectively followed up. The first group had ACI in combination with ACL reconstruction (combined group); the 2(nd) group consisted of individuals who had an ACI procedure having had a previously successful ACL reconstruction (ACL first group); and the third group included patients who had an ACI procedure to a clinically stable knee with documented nonreconstructed ACL disruption (No ACL group). Their outcomes were assessed using the modified cincinnati rating system, the Bentley functional (BF) rating system (BF) and a visual analog scale (VAS). RESULTS: At a mean followup of 64.24 months for the ACL first group, 63 months for combined group and 78.33 months for the No ACL group; 60% of ACL first patients, 72.73% of combined group and 83.33% of the No ACL group felt their outcome was better following surgery. There was no significant difference demonstrated in BF and VAS between the combined and ACL first groups. Results revealed a significant affect of osteochondral defect size on outcome measures. CONCLUSION: The study confirms that ACI in combination with ACL reconstruction is a viable option with similar outcomes as those patients who have had the procedures staged.

Autologous chondrocyte implantation in the knee: mid-term to long-term results.

BACKGROUND: From 1998 to 2008, 1000 skeletally mature patients underwent autologous chondrocyte implantation for an osteochondral defect of the knee. We evaluated the functional outcomes in 827 of 869 patients who had undergone autologous chondrocyte implantation with Chondron or periosteum (ACI-C/ACI-P) or matrix-assisted chondrocyte implantation (MACI) and attempted to identify factors that influenced outcome. METHODS: The age of the patient, the size and site of the osteochondral lesion, previous surgery, and the presence of early osteoarthritis were assessed for their influence on outcomes. Each factor was evaluated in a separate Cox proportional hazards model with use of hazard ratios (HRs), with 95% confidence intervals (CIs), describing the likelihood of failure for that particular factor. Outcomes were assessed with use of the modified Cincinnati score, visual analog scale pain score, and Stanmore functional score. RESULTS: The mean duration of follow-up was 6.2 years (range, two to twelve years). The mean age was thirty-four years (range, fourteen to fifty-six years), with 493 males and 334 females. The average size of the defect was 409 mm2 (range, 64 to 2075 mm2). Four hundred and twenty-one procedures (51%) were performed on the medial femoral condyle; 109 (13%), on the lateral femoral condyle; 200 (24%), on the patella; and fifty (6%), on the trochlea. Kaplan-Meier survival analysis revealed that the unadjusted graft survival rate was 78.2% at five years and 50.7% and ten years for the entire cohort. No difference was found between the survival rates of the ACI-C/ACI-P and MACI techniques (HR = 0.948, 95% CI = 0.738 to 1.219, p = 0.678). There was a significant postoperative improvement in the function and pain scores of all three outcome measures (p < 0.002). Survivorship in the group with a previous cartilage regenerative procedure was inferior to that in patients with a previously untreated lesion, with failure five times more likely in the former group (HR = 4.718, standard error [SE] = 0.742, 95% CI = 3.466 to 6.420, p < 0.001). Degenerative change in any compartment had a significant detrimental effect on survivorship, with survivorship worsening as the osteoarthritis grade increased (Grade 1: HR = 2.077, 95% CI = 1.299 to 3.322, p = 0.002; Grade 2: HR = 3.450, 95% CI = 2.646 to 4.498, p < 0.001; and Grade 3: HR = 3.820, 95% CI = 2.185 to 6.677, p < 0.001). CONCLUSIONS: Our study demonstrated an overall graft survival of 78% at five years and 51% beyond ten years following both autologous chondrocyte implantation techniques. Despite study limitations, our results demonstrate that autologous chondrocyte implantation for the treatment of osteochondral defects of the knee can achieve good results. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.