Foreword.
Excellent long-term results have been achieved with cemented implants. However, the profile of the patient presenting for total hip replacement has changed. Pain and disability are no longer the only indications for surgery. The millennium patient, em-powered with information, seeks surgical intervention to restore quality of life. Thus, ever younger cohorts of patients are presenting for total hip replacement. Conservative surgery embraces both soft issue sparing and bone conservation. If the surgeon is confident the hip he is going to use will outlast the patient he should use it. Otherwise he should consider the next operation and conserve bone. Any implant that makes contact with the diaphyseal cortex or is ingrown distally will offload distally with consequent proximal stress protection. Bone conservation is achieved both by taking less bone at the time of surgery and by optimising the physiological loading of the proximal femur to preserve bone in the longer term. This supplement reviews the evolution and the clinical heritage of a short, stemless metaphyseal loading implant the PROXIMA. Elegant biomechanical studies have shown that the PROXIMA is not a 'fit and fill' prosthesis. Excellent axial and rotational stability can be achieved within the cancellous bone, and the implant is suspended in and moves in consort with the surrounding cancellous bone. This reduces the shear stresses at the fixation interface and optimises load transfer in the metaphysis. Bone densitometry demonstrated that the shorter second generation customised Santori stem avoided subtrochanteric buttressing and enhanced the load transfer to the proximal femur with consequent bone remodelling. Using DEXA to compare the periprosthetic bone density of the short stem with a variety of other commercially available cementless femoral implants confirmed that the PROXIMA preferentially loads the metaphyseal bone. The 'round the corner' technique for the insertion of the PROXIMA is ideally suited for minimally invasive surgical approaches. The 'MicroHip' technique uses a section of the anterior Smith-Peterson approach. This is a truly internervous and inter-muscular plane which provides excellent access to the hip joint. Minimal soft tissue disruption, together with bone preservation, makes PROXIMA a truly conservative op-tion for the millennium patient.
Learmonth
I D
ID
Department of Orthopaedic Surgery, University of Bristol, Bristol - UK.