Minimally invasive periacetabular osteotomy using a modified Smith-Petersen approach: technique and early outcomes.

AIMS: Periacetabular osteotomy is an effective way of treating symptomatic hip dysplasia. We describe a new minimally invasive technique using a modification of the Smith-Peterson approach. We performed a prospective, longitudinal cohort study to assess for any compromise in acetabular correction when using this approach, and to see if the procedure would have a higher complication rate than that quoted in the literature for other approaches. We also assessed for any improvement in functional outcome. PATIENTS AND METHODS: From 168 consecutive patients (189 hips) who underwent acetabular correction between March 2010 and March 2013 we excluded those who had undergone previous pelvic surgery for DDH and those being treated for acetabular retroversion. The remaining 151 patients (15 men, 136 women) (166 hips) had a mean age of 32 years (15 to 56) and the mean duration of follow-up was 2.8 years (1.2 to 4.5). In all 90% of cases were Tönnis grade 0 or 1. Functional outcomes were assessed using the Non Arthritic Hip Score (NAHS), University of California, Los Angeles (UCLA) and Tegner activity scores. RESULTS: The mean pre-operative lateral centre-edge angle was 14.2° (-5° to 30°) and the mean acetabular index was 18.4° (4° to 40°). Post-operatively these were 31° (18° to 46°) and 3° (-7° to 29°), respectively, a significant improvement in both (p < 0.001). Allogenic blood transfusion was required in two patients (1.2%). There were no major nerve or vascular complications, and no wound infections. At the time of last follow-up, we noted a significant improvement in functional outcome scores: UCLA improved by 2.31 points, Tegner improved by 1.08 points, and the NAHS improved by 25.4 points (p < 0.001 for each). Hypermobility and longer duration of surgery were significant negative predictors for a good post-operative UCLA score, while residual retroversion was a positive predictor of post-operative UCLA score. CONCLUSION: We have found this approach to be safe and effective, facilitating early recovery from surgery. Cite this article: Bone Joint J 2017;99-B:22-8.

Radiological changes ten years after St. Georg Sled unicompartmental knee replacement.

Failure of a unicompartmental knee replacement (UKR) may be caused by progressive osteoarthritis of the knee and/or failure of the prosthesis. We have examined the fate of the other compartments of the knee by radiological assessment 10 years after operation. A total of 50 UKRs were performed on 45 carefully selected patients between 1989 and 1992. Fifteen patients died, two patients were lost to follow-up and two knees were revised. Standard long-leg weight-bearing anteroposterior views of the knee and skyline views of the patellofemoral joint were taken pre-operatively and at 8 months and 10 years after operation. The radiographs of the remaining 30 knees were reviewed three times by blind and randomized assessment to measure the progression of osteoarthritis within the joints. Two knees showed evidence of progression of osteoarthritis within the patellofemoral joint and three knees showed some progression of the opposite tibiofemoral compartment--but only on one of the radiological grading systems used for assessment. It is concluded that progression of arthritis in the unreplaced compartments is not a significant problem after fixed bearing UKR.