Abstract
There are a growing number of younger patients with developmental dysplasia of hip, proximal femoral deformity and osteonecrosis seeking surgical intervention to restore quality of life, and the advent of ISTCs has resulted in a greater proportion of such cases being referred to existing NHS departments.
Bone-saving hip athroplasty is often advocated for younger active patients, as they are potential candidates for subsequent revision arthroplasty. If resurfacing is contraindicated, short bone-conserving stems may be an option. The rationale for short stems in cementless total hip arthroplasty is proximal load transfer and absence of distal fixation, resulting in preserved femoral bone stock and avoidance of thigh pain.
We have carried out 17 short stem hip replacements (Mini-hip, Corin Medical, Cirencester, UK) using ceramic bearings in 16 patients since June 2010. There were 14 females and 2 males, with a mean age of 50.1 years (range 35–63 years) at the time of the surgery. The etiology was osteoarthritis in 11, developmental dysplasia in 4, and osteonecrosis of the femoral head in one patient. All operations were performed through a conservative anterolateral (Bauer) approach. These patients are being followed and evaluated clinically with the Harris and Oxford hip scores, with follow-up at 6 weeks, 3 months, and annually thereafter.
Initital results have been encouraging in terms of pain relief, restoration of leg length (one of the objectives in cases of shortening) and rage of movement. Radiological assessment has shown restoration of hip biomechanics. Specific techniques are required to address varus, valgus and femoral deformity with leg length inequality.
There are two main groups of short stems, those that are neck-preserving and those that do not preserve the femoral neck. The latter group requires traditional techniques for revision. Another feature that differentiates them is the availability of modularity. The device we employed is neck-preserving and available with different neck lengths and offsets, which help in restoration of hip biomechanics.
The advantage of such short stems may be preservation of proximal femoral bone stock, decreased stress shielding and the ease of potential revision. Such devices may be a consideration for patients with malformations of the proximal femur. Long-term follow-up will be of value in determining if perceived benefits are realised in practice.
