Hugh P. Chandler

Periprosthetic Femoral Fractures Around Well-Fixed Implants:Use of Cortical Onlay Allografts with or without a Plate

Background: Periprosthetic femoral fractures around hip replacements are increasingly common. When the femoral component is stable, open reduction and internal fixation is recommended in all but exceptional cases. The purpose of this study was to evaluate the outcome of treatment of fractures around stable implants with cortical onlay strut allografts with or without a plate. Methods: A survey of our four centers identified forty patients with a fracture around a well-fixed femoral stem treated with cortical onlay strut allografts without revision of the femoral component. There were fourteen men and twenty-six women, with an average age of sixty-nine years. Nineteen patients were treated with cortical onlay strut allografts alone, and twenty-one were managed with a plate and one or two cortical struts. All of the patients were followed until fracture union or until a reoperation was done. The mean duration of follow-up was twenty-eight months for thirty-nine patients. One patient, who was noncompliant with treatment recommendations, had a failure at two months because of a fracture of the plate and graft. The primary end point of the evaluation was fracture union; secondary end points included strut-to-host bone union, the amount of final bone stock, and postoperative function. Results: Thirty-nine (98%) of the forty fractures united, and strut-to-host bone union was typically seen within the first year. There were four malunions, all of which had <10° of malalignment, and one deep infection. There was no evidence of femoral loosening in any patient. All but one of the surviving patients returned to their preoperative functional level within one year. Conclusions: Cortical onlay strut allografts act as biological bone plates, serving both a mechanical and a biological function. The use of cortical struts, either alone or in conjunction with a plate, led to a very high rate of fracture union, satisfactory alignment, and an increase in femoral bone stock at the time of short-term follow-up. Although this study did not address the potential for later allograft remodeling, our findings suggest that cortical strut grafts should be used routinely to augment fixation and healing of a periprosthetic femoral fracture.

Lipoma arborescens of the knee

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.

Bilobed oblong porous coated acetabular components in revision total hip arthroplasty.

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.

Blood-gas and circulatory changes during total knee replacement. Role of the intramedullary alignment rod.

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)

The role of allografts in the treatment of periprosthetic femoral fractures.

Fracture of the femoral shaft occurring after total hip or total knee replacement is a rare but serious complication1-29,31-37,39-49,52-54. If the prosthesis is loose, the logical treatment is a revision operation with insertion of a femoral component with a longer stem to stabilize the fracture. If the stem is firmly fixed, the best method of treatment is more difficult to determine. The options available include closed treatment (traction or application of a spica cast or a cast-brace), exchange of the stem for a longer one that stabilizes the fracture, supracondylar nailing for a fracture proximal to a total knee prosthesis, and open reduction and internal fixation of the fracture. Closed treatment of a fracture of the femoral shaft is associated with many problems3,5,11,14,15,20,25,29,31,35,48, including medical complications secondary to prolonged bed rest, potential loss of motion of the hip or knee, and non-union or malunion. Malunion is particularly troubling when it is associated with a total hip or knee prosthesis. Malalignment of the femur can accelerate loosening of the implant. Also, revision of a femoral component in the presence of a deformed femur is much more difficult. Exchange of a component that is well fixed (with either cement or bone ingrowth) for a component with a longer stem to stabilize the fracture not only is arduous but also can severely damage the surrounding bone. Anatomical alignment, union of the fracture, and a short recovery time are more likely if the stem is left intact and the fracture is treated with open reduction and internal fixation. ### Proximal Femoral Fractures Distal to a Well Fixed Femoral Stem or Proximal to a Well Fixed Knee Replacement The patient is positioned on his or her …

Revision total hip replacement using the S-ROM femoral component

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.

Reconstruction of major segmental loss of the proximal femur in revision total hip arthroplasty.

Reconstruction of major proximal femoral segmental defects is one of the most difficult challenges in revision total hip arthroplasty (THA). One technique that has been successful is the use of a modular, long-stemmed prosthesis, cemented to an allograft proximal femur and press-fit to the host bone. Since July 1989, the authors have used this technique in 30 hips (29 patients). The trochanteric slide approach was used in all cases. Sixty pounds of weight bearing was encouraged for six weeks, then full weight bearing as tolerated. The mean follow-up period was 22 months (range, two to 46 months). All but two grafts united to the host bone clinically and radiographically. Complications included five dislocations, one graft-host nonunion, one graft resorption, and one deep infection requiring resection arthroplasty. The latter patient was subsequently reconstructed successfully using the same technique. Although the follow-up period is short, the authors have been encouraged by the early success of these allograft-prosthetic composites. Advantages of this approach include rapid return to weight bearing, physiologic loading of the distal femur, and reconstitution of vital proximal bone stock.

Unicompartmental knee replacement: a comparison of constrained and unconstrained designs.

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).

The planning of orthopaedic reconstructive surgery using computer-aided simulation and design

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.

Management of Femoral Bone Stock Deficiency in Total Hip Replacement

Forty-three femoral grafts were used to reconstruct femoral deficiency in revision total hip replacement. Allografts were used in the majority of cases but were always supplemented by autograft. Grafts were used to reconstruct deficiencies of the calcar, cortical perforation, fractures about or below the stem of the femoral component and for massive proximal deficiency of the metaphysis and diaphysis of the femur. These reconstructions were major procedures and complications were significant but comparable to those described for other revision surgery. The infection rate was 5.4%