Biomedical subjects
Publications and source records attributed to Hugh U Cameron.
A review of 241 consecutive total knee revisions has been carried out. Other than loosening, wear, and stiffness, at present, a commoner reason is an unsatisfactory result due to minor errors of tibial and femoral placement. Currently, about 16% of femoral components required derotation during revision.
These knee arthroplasty cases were presented to a panel of surgeon and they represent classic clinical problems: (1) indications for unicompartmental arthroplasty; (2) total knee arthroplasty after a high tibial osteotomy complicated by infection and extensor mechanism rupture; (3) neuropathic arthropathy; (4) posttraumatic osteoarthritis with extraarticular deformity; (5) degenerative arthritis in the young patient; (6) osteoarthritis with a valgus deformity, fixed flexion contracture, degenerative scoliosis, and leg length discrepancy.
A concern about modular stems is that the taper will not provide an adequate seal, causing the stem distal to the taper to become part of the effective joint space. In this study, 380 primary patients and 309 revision patients were treated with a proximally modular stem. Follow-up was between 5 and 17 years (mean 9.4 years). Three patients only had distal osteolysis. All three patients had failure of proximal bone ingrowth. It was concluded that a Morse taper provides an adequate seal or gasket.
Patients with patulous proximal femurs who have hip revision surgery can be treated with reduction osteotomies or with large ingrowth sleeves used with proximally modular stems. Three hundred nine patients had hip revision with >5-years' follow-up (mean 8.6 years). Reduction osteotomies were performed in six patients, all of whom have done well. The overall rerevision rate of 1.7% suggests that either of these methods produces reasonable results in patients with expanded proximal femurs.
The results of treatment of 116 intraoperative femoral fractures were reviewed. Excluding calcar and greater trochanter fractures, there were 14 Type I cases (Vancouver classification). All healed with cerclage wiring. Three cases of vertical fractures of the proximal segment following a subtrochanteric osteotomy did not heal and required revision. There were 8 Type II fractures, most being minor splits or limited, nondisplaced, vertical fractures. Control was lost in 2 wired cases, suggesting that Type II fractures should be converted to Type I by the use of a long stem, or, if impractical, by supplementary fixation. In 7 septic cases, a comminuted fracture occurred during implant removal. An intramedullary nail and cerclage wires were used, and the patients were left with a Girdlestone. The infections were overcome, the fractures healed, and subsequent revision was straightforward, because an open channel existed in the femur.
This case discussion features knee arthroplasty cases presented to a panel of surgeons. The cases were chosen to represent common clinical problems encountered in everyday practice.
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If distal fixation is a goal in revision hip surgery, then modularity may not be necessary. If, however, proximal fixation is desired, both proximal and distal fit and fill are necessary to achieve initial stability. This can only be done in the revision situation by using a modular stem. Long-term follow up of 320 revision cases treated using a proximally modular proximal ingrowth stem shows a re-revision rate for late aseptic loosening of 0.93% at a mean time of 7 years, indicating that such a stem is a reasonable option.
A prospective study was carried out on the use of a proximally modular, proximal ingrowth noncemented stem in hip revision surgery. There were 109 short stems and 211 long stems. The mean follow-up was 7 years (range, 2-12 years). No revisions were required in the short-stem group for aseptic loosening; 3 (1.4%) revisions were required in the long-stem group. Lucency was absent in 91.7% of short-stem cases, was low grade in 7.2%, and was high grade in 1.1%. In the long-stem group, lucency was absent in 72.9% of cases, was low grade in 24.5%, and was high grade in 2.6%. No measurable subsidence occurred in the short-stem group, and 5 mm of subsidence occurred early in 2 of the long-stem group. This subsidence stabilized subsequently. Osteolysis distal to the sleeve was not observed. A proximal ingrowth, proximally modular stem can be used in revision hip surgery.
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