Comparison of three surgical techniques of posterolateral knee reconstruction: A cadaver study.

BACKGROUND: Injuries to the posterolateral corner (PLC) of the knee are often overlooked but, require reconstruction in order to restore stability in varus and external rotation. Among the many anatomic and non-anatomic PLC reconstruction techniques available, the modified Larson (mLR), LaPrade (LPR) and Versailles reconstruction (VR) procedures are widely used. HYPOTHESIS: The hypothesis was that anatomic PLC reconstruction (VR and LPR procedures) provides better restoration and control of external rotation. PATIENTS AND METHODS: Fifteen fresh-frozen cadaveric knees were tested to compare the 3 procedures. Varus laxity on stress radiographs in full knee extension and external rotatory laxity on dial test at 30° flexion were quantified at 3 phases: intact knee, PLC sectioned and PLC reconstructed. RESULTS: Mean varus laxity did not differ significantly between techniques in intact knees (p=.14), after PLC sectioning (p=.14) or after PLC reconstruction (p=.17). After PLC reconstruction, varus laxity was restored, with no statistical difference between mLR, VR and LPR compared to intact test values (respectively, -1.0, -1.3 and -1.5; p=.98). In all 3 groups, mean external rotation laxity on dial test at 30° flexion did not significantly differ between intact knees (p=.32) and after PLC sectioning (p=.15). After PLC reconstruction, the mLR technique was significantly less effective in restoring rotational stability than the VR and LPR techniques (p=.025). DISCUSSION: The VR technique provided similar outcomes to LPR for restoring stability in varus and external rotation. The 2 "anatomic" reconstruction procedures (VR and LPR) were significantly more effective than the modified Larson technique for external rotation control, confirming the study hypothesis. Consequently, it remains preferable to use anatomic techniques in multiligament injuries involving the PLC. LEVEL OF EVIDENCE: IV, cadaver study.

Outcomes after revision of metal on metal hip resurfacing to total arthroplasty using the direct anterior approach.

BACKGROUND: Function after revision total hip arthroplasty (THA) in failed metal-on-metal (MoM) hip resurfacing arthroplasty (HRA) is variable, but post-operative complication rates are reportedly high. We hypothesized HRA conversion to THA using the direct anterior approach (DAA) would be associated with optimal outcome. METHODS: Seventeen MoM-HRAs in 15 patients (seven males, eight females) were revised through the DAA. The mean age was 45 years (28-59 yrs). The most common indications for revision were aseptic loosening of the acetabular component or of the femoral component and femoral neck fracture. In 16 hips, a conversion to a ceramic-on-ceramic (CoC) (13 hips) or to a metal-on polyethylene (MOP) (2), or to a large-head MoM (1) THA was done. An isolated femoral revision was done in one hip. RESULTS: After 6.7 ± 3 years, no hip had required a re-revision. The Postel-Merle d'Aubigne (PMA) functional score improved from 9 (4-14) to 16 (12-18) (p < 0.001). An intra-operative fracture of the greater trochanter (one hip) and dysesthesia of the lateral femoral cutaneous nerve (four hips) were reported. Mean serum chromium concentration decreased from 33.2 µg/L (11.8-62 µg/L) pre-operatively to 5.8 µg/L (0.4-35.5 µg/L) post-operatively (p < 0.001), and mean serum cobalt concentration decreased from 35.8 µg/L (6.3-85.5 µg/L) to 4.7 µg/L (0.26-25.7 µg/L) (p = 0.003). CONCLUSION: Revision of failed MoM-HRA using the DAA resulted in an acceptable clinical outcome, no specific complication and no further surgery. A consistent decline in serum ion levels may be expected following HRA conversion to THA.