A simple technique for defatting morsellised bone graft in revision hip arthroplasty.

A method for producing fat-free, non-saline laden morsellised bone graft for use in revision hip arthroplasty is described. The method is easily performed, requires inexpensive and readily available equipment and, we believe, reduces loss of bone graft compared with alternative techniques. (Hip International 2002; 4: 403-4).

Dual aetiology hip pain requiring total hip arthroplasty in hereditary multiple exostoses: A case report and review of the literature.

We report a case of hereditary multiple exostoses (HME) presenting with avascular necrosis of the femoral head and mechanical impingement of an exostosis treated by total hip replacement. (Hip International 2002; 4: 397-9).

Laparoscopic forceps--a useful tool in revision hip arthroplasty.

During revision hip arthroplasty, distal cement plugs and broken instrument tips in the femoral canal pose quite a challenge. We report the use of laparoscopic forceps to facilitate their removal thereby avoiding complications associated with other methods previously described.

McIndoe's scissors--a simple technique to aid distal locking of an intramedullary nail.

Distal locking of intramedullary nails may be difficult and time consuming. We describe a simple technique using a readily available instrument (McIndoe's scissors) to aid start of this procedure and to locate both distal locking holes at one time. By holding the scissors out of the operative field and facilitating rapid incisions, the operative procedure time and, importantly, the radiation exposure time may be reduced.

Inaccuracy of acetabular reaming under surgical conditions.

Press-fit uncemented acetabular components require accurate implant-bone cavity fit. Ten cavities produced during actual hip arthroplasty using debris-retaining reamers were replicated in dental alginate. An experimental reamer with better cutting prepared 12 acetabulae in mortuo under similar conditions. Positives in dental stone were measured on a coordinate measuring center. Spheres of best-fit and variation of each point from these spheres were calculated. Control cavities in polyurethane foam were measured to estimate casting errors. Diametral errors of conventionally reamed cavities averaged 2.1%, whereas experimental reamers' cavities varied by 0.5% (P < .005). Overall surface variation from hemispheric form in conventionally reamed cavities exceeded the experimental reamer's results (P < .005). Conventional acetabular reamers cut bone inaccurately. Reamers designed for improved bone cutting reduce cavity errors.

The position of the popliteal artery in the arthritic knee.

We studied the position of the popliteal artery in 32 patients with primary osteoarthritis of the knee. A total of 45 knees were studied using a noninvasive technique with color-flow duplex scanning. The distance between the popliteal artery and the posterior tibial cortex was measured in various positions of flexion. The distance separating them was found to be maximal between 60 degrees and 90 degrees. The study was repeated in a smaller series of 17 patients (20 knees) after knee replacement but with less conclusive results. We believe the safest position on which to operate in primary arthroplasty is with the knee in flexion, but the safety margins are not the same in revision surgery.

Press-fit acetabular cup fixation: principles and testing.

Pre-clinical testing of the fixation of press-fit acetabular components of total hip prostheses relies on cadaver or synthetic bone, but the properties and geometry of bone models differ from those of physiological bone. Cup designs use varied mechanisms for initial stability in bone; therefore, using different analogues and tests is appropriate. Press-fit cup stability was tested in the following: firstly, polyurethane (PU) foam modelling cancellous support; secondly, glass-fibre reinforced epoxide (GFRE) tubes modelling acetabular cortical support; thirdly, cadaveric acetabula. Three commercial cups [Harris-Galante II (H-G-II), Zimmer; Optifix, Smith & Nephew, Richards; porous coated anatomic (PCA), Howmedica] and an experimental cup with enhanced rim fixation were tested in three modes: direct pull-out, lever-out and axial torque. The fixation stabilities measured in the PU and the GFRE models showed trends consistent with those in cadaver bone, differing in the oversizing and cup geometry. The experimental cup was significantly more secure in most modes than other cups; the H-G II and Optifix cups showed similar stabilities, lower than that of the experimental cup but greater than that of the PCA cup (analysis of variance and Tukey's highly significant test; p < 0.001). The stabilities measured in cadaver bone more closely approximated those in GFRE. The use of several bone analogues enables separation of fixation mechanisms, allowing more accurate prediction of in vivo performance.

Closed rupture of the posterior tibial artery secondary to a soccer injury.

Arterial damage following blunt trauma is uncommon and is usually the result of high-energy injury. We report a case of posterior tibial artery rupture after a closed distal tibial fracture, sustained during a low-energy soccer tackle.

Reconstruction femoral nailing for nonunion of subtrochanteric fracture: a revision technique following dynamic condylar screw failure.

We report two cases of nonunion of subtrochanteric fractures associated with failure of fixation with a dynamic condylar screw (DCS) due to plate fracture. In both cases the nonunion was successfully treated by insertion of a reconstruction femoral nail. This implant allowed early weightbearing despite the patients' advanced age and poor bone quality. We did not perform direct bone grafting and the fractures healed without complication.

Weight changes after total hip arthroplasty.

A survey is presented that contradicts the often quoted teleologic argument that restricted mobility is the limiting factor in weight reduction in overweight patients needing a total hip arthroplasty. One hundred fifty patients were reviewed at 1 year after arthroplasty. All reported improved mobility, but there was no evidence of a trend toward weight loss. More complications with overweight patients were observed. This is useful information in encouraging overweight people to lose weight prior to hip arthroplasty, and could be extrapolated to other procedures.

Traumatic medial displacement of Rotalok uncemented acetabular component. A case report.

The failure of uncemented acetabular components has been described in association with component wear, disassembly, and proximal migration. The authors report a case of medial displacement following minor trauma some 18 months after surgery. The component involved differs in design from both press-fit, porous-coated or screw-in, fully threaded acetabular cups. The authors suggest that additional screws should be inserted to enhance long-term stability.

Failure of acetabular cups influenced by marker wire anchorage.

Failure of an acetabular cup is uncommon and has been attributed to wear or creep, trauma or bony irregularities in the acetabulum. We report ten cases in which fracture of the cup occurred at the site of drill holes used to anchor the marker wire. The role of such indentations as stress raisers has not been previously reported; we suggest that deep indentations or grooves should not be placed in the most highly stressed areas and that the cup thickness should allow for predicted wear rates.