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BACKGROUND: To our knowledge, the medium to long-term outcome after revision knee arthroplasty with structural allograft augmentation for reconstruction of uncontained defects has not been determined. The purpose of the present study was to assess the outcome for patients managed with such a procedure. METHODS: We prospectively followed fifty patients who had fifty-two revision knee replacements with sixty-six structural grafts performed at three institutions. Twenty-nine knees (twenty-seven patients) were independently evaluated at a mean of 96.9 months (range, sixty to 189 months) by an investigator who had not been involved in the index procedure. Twelve knees (23%) had a repeat revision at a mean of 70.7 months (range, twenty-six to 157 months). The allograft was retained in two of these patients. Eleven patients died at a mean of ninety-three months (range, sixty-one to 128 months) after the procedure; the structural allograft and implants were intact, and the patients were not awaiting revision at the time of death. RESULTS: Clinical evaluation revealed that the mean modified Hospital for Special Surgery knee score had improved from 32.5 points preoperatively to 75.6 points at the time of the review and the mean range of motion had increased from 60.5 degrees preoperatively to 88.6 degrees. Failure was defined as an increase of less than 20 points in the modified Hospital for Special Surgery knee score at the time of the review or the need for an additional operation related to the allograft. Thirteen knee replacements failed, yielding a 75% success rate. Five knees had graft resorption, resulting in implant loosening. Four knee replacements failed because of infection, and two knees had nonunion between the host bone and the allograft. Two knees (one patient) did not have a 20-point improvement in the knee score. The survival rate of the allografts was 72% (95% confidence interval, 69% to 75%) at ten years. On radiographic analysis, none of the surviving grafts had severe resorption, one had moderate resorption, and two had mild resorption. One knee had a loose tibial component, and three knees had nonprogressive tibial radiolucent lines. All four knees were asymptomatic. CONCLUSIONS: Our results demonstrate that allografts used in revision knee replacement in patients with the difficult problem of massive bone loss have an encouraging medium-term rate of survival.

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Thirty-eight oblong bilobed noncustom uncemented, porous-coated titanium acetabular components were used to reconstruct failed hip arthroplasties with large superior segmental acetabular bone deficiencies. No structural bone grafts were used. All patients were followed up for 2 to 5 years (mean, 3 years) after the operation. One patient (whose socket rested primarily on a structural bone graft from a previous procedure) had revision surgery for acetabular loosening. No other patients have had revision surgery or had another ipsilateral hip operation. At latest followup, 35 patients had no or mild pain and two patients had moderate pain. Two implants migrated more than 2 mm in the first year, then stabilized. On the latest radiographs, two implants had bead shedding, but there was no measurable migration or change in position. For selected patients with large superolateral acetabular bone deficiencies, this implant facilitated a complex reconstruction, provided good clinical results, and showed satisfactory stability at early to midterm followup in most patients.

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Lipoma arborescens is a rare intra-articular lesion, characterised by diffuse replacement of the subsynovial tissue by mature fat cells, producing prominent villous transformation of the synovium. The aetiology of this benign condition is unknown. We describe six cases involving the knee, discussing the symptoms, diagnosis and treatment.

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The proximally porous-coated, modular S-ROM femoral component was used in 52 complex total hip revisions done in 48 patients. These patients had severe bone loss, leg length inequality, and instability. Twenty-two patients required structural femoral allografts; 8 had previous resection arthroplasties for sepsis. The mean number of previous hip operations was 3. The stem was press fit, and the metaphyseal sleeve was selectively cemented to the allograft. The preoperative Harris rating was 44 points; at a mean of 3 years, followup was 82 points. Eighty-four percent of the patients were satisfied with their outcomes. No radiographic or histologic evidence of fretting at the modular sleeve-stem junction or along the stem was seen. Significant thigh pain persisted in 2 patients and was directly related to stem diameters > 17 mm. Complications in these complex cases were not infrequent, reflecting the need for allograft augmentation, and included greater trochanter bursitis and nonunion in 20 hips, minor nonpropagating fracture in 13 hips, and 12 dislocations. Mechanical loosening occurred in 5 hips. There were no complications attributable to the S-ROM modular femoral component, and the prosthesis has proven to be versatile and did well in these very difficult cases.

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Nineteen patients with 19 fractures around or below a well-fixed femoral stem, were treated by open reduction and internal fixation using massive cortical allograft struts and cerclage wires or cables. The first procedure was performed in 1982 and the last in 1990. Follow-up averaged 28 months. Seventeen patients united their fractures and returned to their preoperative functional status at an average time of 41/2 months. Sixteen healed anatomically. There was one mild malunion and there were two nonunions, both requiring further surgery.

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Seventy-six patients who had eighty-seven unicompartmental knee replacements were followed for an average of fifty-three months (range, two to twelve years). The operation was on the medial side in eighty-two knees and on the lateral side in five. Fifty replacements were unconstrained and thirty-seven were constrained. Of the fifty knees that had an unconstrained replacement, forty-nine (98 per cent) had a good or excellent result, compared with only twenty-six (70 per cent) of the knees that had a constrained replacement; the difference is significant (p = 0.0007). No knee that had an unconstrained replacement had a poor result, compared with nine (24 per cent) of the knees that had a constrained replacement (p = 0.0009). Four (8 per cent) of the fifty knees that had an unconstrained replacement later had a revision total knee arthroplasty, compared with ten (27 per cent) of the thirty-seven knees that had a constrained replacement; the difference is significant (p = 0.04). Noteworthy degenerative changes in the opposite compartment occurred in only one of the eighty-seven knees (a knee in which an unconstrained prosthesis had been inserted).

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Bone allografts were used to reconstruct deficient acetabular and femoral bone in eighteen patients during two-stage revision of a hip arthroplasty that had failed due to infection. At a mean of 4.2 years after reimplantation, only two patients had had recurrence of the infection. Four patients needed another revision arthroplasty for reasons other than infection. These results suggest that allografts of bone are useful for the reconstruction of osseous deficiencies in carefully selected patients who have a hip arthroplasty after infection. The results do not support the concern that allografts that are used under these circumstances necessarily lead to a high rate of recurrence of infection. However, the long-term results of the use of allografts in hip arthroplasty after infection remain unknown.

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High out-of-plane forces acting on the hip joint can produce important rotational micromotion of the femoral component. This micromotion at the prosthesis interface may be detrimental to the stability of the implant. In cementless femoral implants this could prevent bone ingrowth, and in the cemented component this could cause generation of particulate debris, lysis, and loosening. The introduction of the torque wrench micrometer for assessment of intraoperative femoral component stability can quantify the initial stability of primary cementless femoral components and critically evaluate the stability (at either the initial or revision arthroplasty) of both cemented and cementless femoral components. It allows the surgeon to produce a known torque in the direction and magnitude of the out-of-plane forces that load the hip in vivo.

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The use of an intramedullary alignment rod in the distal part of the femur is an important step in performing total knee-replacement arthroplasty. On the basis of our observation of a sudden decrease in oxygen saturation in some patients after insertion of the rod, a prospective study was done of the circulatory and blood-gas changes that were associated with insertion in thirty-five patients. We examined the effects of the use of an eight-millimeter solid alignment rod, with and without venting; an eight-millimeter fluted alignment rod, with venting; and an eight-millimeter fluted or solid alignment rod, inserted through a 12.7-millimeter drill-hole, but without other venting. A statistically significant reduction in oxygen saturation, arterial oxygen tension (PaO2), and end-tidal carbon-dioxide tension (PETCO2) occurred after insertion of both solid and fluted eight-millimeter alignment rods through an eight-millimeter hold in both vented and unvented femoral canals, in association with a significant increase (p less than 0.01) in intramedullary pressure. Bone-marrow contents and fat were retrieved from samples of blood from the right atrium, indicating that embolization of marrow contents had occurred during insertion of the alignment rod. A small decrease in systemic blood pressure and heart rate also occurred. These changes were completely eliminated by the use of a 12.7-millimeter drill-hole as the entry site of the eight-millimeter fluted rod. We concluded that insertion of an intramedullary alignment rod in the femur causes embolization of marrow contents, which decreases arterial oxygen tension, oxygen saturation, end-tidal carbon-dioxide tension, arterial blood pressure, and heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

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Three-dimensional reconstructions from computed tomographic (CT) images are currently being used clinically in a wide variety of orthopaedic surgical applications. The computer may be used to select the optimum standard artificial joint replacement or to design a custom artificial joint replacement for a particular patient. Where large bony defects exist, the computer may be used to design bone allografts for joint reconstruction and to manufacture models of the bones for use in planning the surgery. In cases where osteotomies are performed to improve the mechanics of the joint, each proposed osteotomy may be simulated on the computer to identify the surgical plan that will optimally normalize the diseased joint.

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Three-dimensional computer reconstructions of bony anatomy based on computed tomographic images and radiographs may be used to analyze, simulate, and design certain orthopedic procedures. In osteotomy surgery, the computer-reconstructed models may be used to measure critical angles, surface area, and congruity of the joint surfaces. Computer reconstructions may be used in total joint replacement surgery to simulate the effect of surgical reamers and rasps, to select the geometrically optimum standard implant, or to design a custom implant. In allograft reconstructive surgery, computer reconstructions may be used to measure bony defects and to identify the appropriate allografts for the reconstruction. Plastic models may be sterilized and used as templates to sculpt the allografts immediately preoperatively. In all three applications in orthopedic surgery, three-dimensional, computer-aided reconstructions have the potential to improve results and reduce morbidity.

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Eight of forty-one patients undergoing total hip replacement experienced acute but not fatal renal failure postoperatively. All forty-one patients received transfusions of frozen blood and albumin and their wounds were irrigated with a bacitracin-neomycin-polymyxin solution. All subsequently had some relative hypotension. None of a second, prospective group of fifty-five patients who received the transfusion of albumin, but not frozen blood or the bacitracin-neomycin-polymyxin irrigant, had renal failure. The incidence of hypotension in this group was comparable to that in the first group, yet no cases of renal failure were seen. We therefore recommend that the combination of frozen blood and potentially nephrotoxic drugs be avoided in patients undergoing total hip replacement.

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