Os calcis lipoma: To graft or not to graft? - A case report and literature review.

BACKGROUND: Intraosseous lipoma is a rare benign lesion, commonly affecting the os calcis. Its pathogenesis and natural history are not fully understood, and its management remains controversial. CASE SUMMARY: A 56-year-old male complaining of heel pain was diagnosed with an os calcis lipoma. The lesion was treated with curettage and it was filled with impacted allograft and demineralized bone matrix. Histological examination confirmed the above diagnosis. Six months postoperatively, the patient returned to recreational long-distance running. Repeated computed tomography scanning, up to five years postoperatively, showed almost complete resorption of the graft over time. CONCLUSION: The treatment of an os calcis lipoma should be individualized, depending on the symptoms, the location and size of the lesion. Surgeons, electing to proceed with bone grafting, should consider the probability of bone graft resorption.

Granulomatous Lung Disease: A Novel Complication following Metallosis from Hip Arthroplasty.

A case of a female patient with local and systemic complications of metallosis, following catastrophic wear of a revised hip arthroplasty, is presented. The patient had a history of a fractured ceramic-on-ceramic implant, exchanged with a metal-on-polyethylene prosthesis. Systemic complications included sarcoidosis-like reactions, presenting as granulomatous lung disease, along with chorioretinitis, erythema nodosum, and cardiomyopathy. High local and circulating cobalt and chromium levels established the diagnosis. The patient underwent extensive debridement and implant revision. One year postoperatively, she had no respiratory symptoms or functional impairment. Local and systemic complications of metallosis after hip arthroplasty should be promptly recognized and treated operatively.

Effect of bearing geometry and structure support on transient elastohydrodynamic lubrication of metal-on-metal hip implants.

An effective lubrication can significantly reduce wear of metal-on-metal artificial hip joints. The improvement of the lubrication can be achieved through the optimisation of the bearing geometry in terms of a small clearance and/or the structural support such as a polyethylene backing underneath a metallic bearing in a sandwich acetabular cup form. The separate effects of these two factors on fluid film lubrication of 28 mm diameter metal-on-metal total hip joints under walking conditions were numerically investigated in this paper. The results show that a larger lubricant film due to the polyethylene backing can be significantly enhanced by the transient squeeze-film action, particularly during the stance phase, and a similar lubricant film can be developed for both the monolithic cup relying on the smaller clearance and the sandwich cup benefiting from the polyethylene backing. Both cup systems can function in a wide range of lubrication regimes, covering both mixed and fluid film, under the current design and manufacture conditions.

Polymethylmethacrylate arteriography--A complication of total hip arthroplasty.

We report a complication of contemporary cementing technique in total hip arthroplasty, that is, extensive retrograde filling with polymethylmethacrylate cement of the nutrient artery of the femur.

Poor predictive value of broad-range PCR for the detection of arthroplasty infection in 92 cases.

BACKGROUND: The diagnosis of prosthetic infection remains a challenge, as no test is 100% sensitive and 100% specific. Recent advances in molecular biology have enabled the detection of infection in culture negative cases. PATIENTS AND METHODS: We evaluated the effectiveness of polymerase chain reaction (PCR) in detecting infection in failed joint replacements prospectively in 91 consecutive patients (92 prosthetic joints) undergoing revision total hip or knee arthroplasty. Synovial fluid was collected intraoperatively and examined by broad-range PCR assay for detection of bacterial DNA. The clinical diagnosis of infection was based on the results of blood tests, preoperative joint aspiration, culture and histology of multiple intraoperative tissue samples, as well as the surgeon's assessment. 12 joints (13%) were infected, but the PCR was positive in 32 cases. The sensitivity of the technique was 92%, the specificity 74%, the accuracy 76%, the positive predictive value 34%, and the negative predictive value was 98%. INTERPRETATION: The PCR technique cannot be recommended for the routine detection of prosthetic infection. The large number of false positive results may represent sample contamination, or bacterial presence related to low-virulence organisms, low bacterial load, or a strong host immune response.

The evolution of hip resurfacing arthroplasty.

Metal-on-metal hip resurfacing, a significant recent development in hip arthroplasty, preserves proximal femoral bone stock, optimizes stress transfer to the proximal femur, and offers inherent stability and optimal range of movement. The results of hip resurfacing in the 1970s and 1980s were disappointing, and the procedure was largely abandoned by the mid-1980s. The renaissance of metal-on-metal articulations for total hip arthroplasty has enabled the introduction of new hip resurfacings, and many implant manufacturers have introduced such systems. Early results are encouraging, and complications commonly seen in the 1970s and 1980s, such as early implant loosening and femoral neck fracture, are rare. Background research and better understanding of implant failure suggest that current hip resurfacing technology has developed beyond that of an experimental procedure.

Influence of the clearance on in-vitro tribology of large diameter metal-on-metal articulations pertaining to resurfacing hip implants.

Large-diameter metal-on-metal articulations may provide an opportunity for wear reduction in total hip implants because earlier studies have shown that the formation of a fluid film that completely separates the bearing surfaces is theoretically possible. In such a lubrication mode and under ideal conditions, there is theoretically no amount of wear. Studies have suggested that the two primary parameters controlling the lubrication mode are the diameter and the clearance of the articulation. The goal of the present study was to experimentally investigate the influence of these two parameters on the wear behavior of large-diameter metal-on-metal articulations pertaining to resurfacing hip implants. The results of this in vitro investigation showed that longer running-in periods and higher amounts of running-in wear were associated with larger clearances.

The Long Gamma Nail for stabilisation of existing and impending pathological fractures of the femur: an analysis of 48 cases.

The results in a series of 42 patients with 48 impending or complete pathological femur fractures stabilised with the Long Gamma nail (Howmedica-Osteonics, Rutherford, NJ,USA) are presented. Twenty two impending and 26 completed pathological femoral fractures treated between 1995 and 1999 were retrospectively analysed. The mean age of the patients was 65.7 yrs (range: 40 to 88). All patients were treated with an 11-mm diameter Long Gamma Nail, inserted through a 5-cm incision proximal to the greater trochanter using the antegrade reaming technique. The mean surgical time was 98 minutes (range: 65 to 225). Reliable stability was achieved in all cases and pain relief was excellent. Complications included 2 superficial and 1 deep wound infections, 4 chest infections, 2 urinary tract infections, and 2 deaths in the recovery. Implant failure occurred in one patient and needed revision to a long stemmed total hip prosthesis. The Long Gamma nail offers the advantage of a technically less demanding percutaneous insertion through the tip of the greater trochanter, secure proximal femoral fixation and the ability to allow immediate or early weight-bearing ambulation. Because of these advantages, we recommend the use of the Long Gamma nail for stabilisation of pathologic and impending pathologic fractures of the femur.

Suction dressings in total knee arthroplasty--an alternative to deep suction drainage.

A new technique is described for dressing of surgical wounds in total knee arthroplasty that is a combination of a semi-permeable dressing and suction drainage. This technique has been used in 100 consecutive cases and drainage was collected in 92. The average volume was 198 ml (range 30 to 850 ml). There was no superficial or deep sepsis. Haematoma formation causing moderate soft tissue tension and some patient discomfort was noted in 9 knees. This form of postoperative wound management retains the nursing and hygiene advantages of deep suction drainage, whilst avoiding the patient discomfort and potential complication possibilities associated with deep internal drainage.

Fracture of the femoral component of a Brigham unicompartmental knee: a case report.

We report the failure of a femoral component in a unicompartmental knee replacement 6 years after implantation. The implant fractured 15 mm from the anterior tip, and scanning electron microscopy confirmed fatigue to be the cause of failure. The clinical and laboratory findings are presented, and the causes and implications of this mode of implant failure are discussed.

Howse II cemented titanium metal-backed acetabular cups: poor 10-year results in 107 hips.

We report a retrospective clinical and radiographic review of 107 consecutive primary total hip replacements, using the cemented Howse II prosthesis. The review concentrates on the long-term performance of the acetabular cup, which was designed with a cylindrical titanium metal backing and a polyethylene liner. In all the hips in the series, this cup was used with a modular titanium straight femoral stem and a 32-mm diameter titanium head. At a mean follow-up of 9.8 (7-11) years, 28 hips had already been revised and 10 others were recognized as clinical or radiographic failures. The indication for revision in 26 of the hips was aseptic loosening and the mean time to revision was 7.2 (3.7-10.9) years This metal-backed cup has only 42% survival at 10 years, which seems to be related to certain of its design features. These include an inadequate thickness of polyethylene sterilized by gamma irradiation in air, a lack of mechanical bonding between the liner and its metal shell, and the high wear rate from the use of a 32-mm titanium femoral head.

Rapid sequence quadruple joint replacement in a rheumatoid Jehovah's Witness.

We report the case of a wheelchair-bound rheumatoid Jehovah's Witness who underwent rapid sequence, staged, simultaneous ipsilateral hip and knee replacements. Using perioperative erythropoietin and postoperative blood salvage, all four joints were reconstructed without homologous blood transfusion. One year following surgery, the patient has achieved an independent functional status, and all four replaced joints remain painless.

Mid-term results and migration behaviour of a ti-alloy cemented stem.

Between 1991 and 1994, 147 patients (154 hips) underwent a primary cemented total hip replacement using the Ultima ti-alloy, collarless, double-tapered stem and a UHMWPE cup. The average age at operation was 66.4 years. Ninety-one patients (97 hips) were available for review with an average follow-up of 76 months. The Harris hip score had improved from pre-operative average of 43.1 (12.5-65.0) to the latest score of 88.9 (67.5-100). There were 11 revisions in total, eight of which were for aseptic stem loosening. The results of Kaplan-Meier survival analysis, based on stem revision for aseptic loosening as an end-point, was 92% at 8 years. Early stem migration analysis at 2 years was possible in 114 cases using digitised radiographs analysed by the EBRA method. Sixty-three stems had not migrated and 35 migrated less than 2 mm with only one of these ending in failure. Sixteen stems showed early migration of more than 2 mm and five of these failed. Early stem migration is predictive of stem failure. Osteolytic lesions occurred in 12 femurs and four of these stems failed.