BackgroundLipped or elevated acetabular liners are frequently used in total hip arthroplasty to improve stability. However, the optimal position of the lip is not known. The purpose of this study was to determine the optimal position of lipped acetabular liners in total hip arthroplasty performed with a posterior approach.MethodsIn 14 hips, lipped trial liners were placed intraoperatively in various positions around the posterior clock-face of the implanted acetabular shell component. For each liner position, stability of the hip was tested at maximal hip flexion with gradually increasing internal rotation until subluxation occurred, at which point the position of the hip was measured using smartphone accelerometer-based goniometers. Smartphone goniometers were first validated against a computer-assisted navigation system. Post-operative radiographs were analyzed for cup inclination angle, cup anteversion angle, and femoral offset.ResultsMean cup inclination angle in our series was 31° ± 6°. The most common liner position that imparted the greatest stability to posterior subluxation was posteriorly and inferiorly (4 o’clock position for left hip, or 8 o’clock position for right hip). The range for most stable liner position for different patients varied from postero-superior (11 o’clock/1 o’clock position) to directly inferior (6 o’clock position). Comparing a non-lipped liner to a lipped liner placed in the optimal position, the average difference in internal rotation gained before dislocation was 23°. There was no association between cup inclination or anteversion angle with liner position of greatest stability.ConclusionIn hip replacements performed through a posterior approach and with mean cup inclination angle of 31° ± 6°, placing the lip of the elevated liner in the postero-inferior quadrant may impart more stability than in the postero-superior quadrant.

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Through-and-through gunshot wounds of the foot present the unique problem of needing to fill a defect while at the same time providing coverage of the dorsum and plantar surface of the foot. A series of 5 patients from 2 institutions is presented. These patients all sustained gunshot wounds that penetrated the forefoot, leaving a rim of uninjured soft tissue and bone around the periphery. All patients were reconstructed with free-tissue transfers, but no bone grafting was required to replace missing bone. One patient did have an arthrodesis and wedge osteotomy to help with walking mechanics. Soft-tissue reconstruction only is adequate to restore the foot sufficiently to allow the patient to walk satisfactorily.