Early complications of primary total hip arthroplasty in the supine position with a modified Watson-Jones anterolateral approach.

BACKGROUND: For total hip arthroplasty (THA), minimally invasive surgery (MIS) has been developed to reduce incision length, muscle damage, and a shorter hospital stay. However, reduced exposure of anatomical landmarks may result in technical errors and inferior implant survivorships. The aim of this study was to report the short-term results and clinical complications of primary MIS THA in the supine position. METHODS: A consecutive series of 103 patients who underwent MIS cementless THA with a modified Watson-Jones anterolateral approach (AL) were enrolled. Outcomes data were reviewed at a minimum of 12 months following the procedure. Clinical evaluations were made using the Merle d'Aubigne and Postel hip score. The results of these procedures were retrospectively compared with those of a historical series of 98 total hip arthroplasties that had been performed by the same surgeon with use of a posterolateral approach (PL). RESULTS: In the MIS AL THA group, intraoperative fracture was observed in 6 hips; 3 in greater trochanter and 3 in calcar femoral. One hip was subjected to irrigation because of postoperative infection was suspected. In the PL group, intraoperative fracture was demonstrated in 4 hips in calcar femoral. No postoperative dislocation and no pulmonary embolism or nerve paralysis was observed in both groups. CONCLUSIONS: The MIS AL THA did not show a clinically relevant superior outcome compared with the PL THA. When performing MIS AL THA, special attention should pay for prevention of greater trochanter fracture.

The intraoperative gap difference (flexion gap minus extension gap) is altered by insertion of the trial femoral component.

A Tensor/Balancer device has been recently developed in order to assess soft tissue balancing in total knee arthroplasty (TKA) under more physiological conditions. This device allows us to measure the joint gap with a trial femoral component in place with the patella reduced. The purpose of this study was to clarify whether the placement of the component changes the intraoperative gap difference (flexion gap distance minus extension gap distance). We prospectively investigated the extension (0°) and flexion (90°) gaps in 73 posterior-stabilized TKAs under 30 lb of joint distraction force. Then, we compared the gap difference with and without the trial femoral component in place. Our results showed that the intraoperative gap difference with the trial femoral component in place was larger than the intraoperative gap difference without the trial component (p=0.00003; with the trial component: mean 4.7 mm (standard deviation (SD): 3.0mm); without the trial component: mean 2.7 mm (SD: 3.3mm)). We consider that the change in gap difference with or without femoral component was caused by a relative difference in the elasticity and/or tightness of the soft tissue in extension versus flexion. Surgeons should be aware of this effect of the femoral component when considering intraoperative soft tissue balancing which leads to postoperative stability of the knee joint consequently.