Subvastus and medial parapatellar approaches in total knee arthroplasty.

This retrospective study compared the outcome of two consecutive groups of patients having primary total knee arthroplasty. The arthroplasties were performed in the first group (169 arthroplasties in 143 patients) from 1988 to 1992 using a medial parapatellar approach, and in the second group (167 arthroplasties in 148 patients) from 1992 to 1996 using a subvastus approach. The patient outcomes were evaluated at 6 months, and were based on clinical and radiographic measures, occurrence of intraoperative lateral retinacular release, and incidence of postoperative patellar subluxation. There were no significant differences between the two groups for range of motion, Knee Society knee and function scores, and stair climbing ability. The patella tracked centrally in significantly more knees with the subvastus approach (139 of 167 knees, 83%) than with the parapatellar approach (107 of 169 knees, 63%). There were significantly fewer knees in the subvastus group requiring a lateral retinacular release (62 of 167 knees, 37%), compared with the parapatellar group (113 of 169 knees, 67%). The authors concluded that the subvastus approach led to improved patellar tracking and stability. Although the surgical and rehabilitative protocols were identical for both groups, the results may have been affected by changing circumstances during the 9-year period of the study.

Infection after total knee arthroplasty. A retrospective study of the treatment of eighty-one infections.

BACKGROUND: The clinical presentation of an infection at the site of a total knee arthroplasty can be used as a guide to treatment, including the decision as to whether the prosthesis should be retained or removed. We reviewed the results of treatment of infection after total knee arthroplasty to evaluate the effectiveness of four treatment protocols based on the clinical setting of the infection. METHODS: We retrospectively evaluated the results of treatment of eighty-one infections in seventy-six consecutive patients who either had an infection after a total knee arthroplasty or had multiple positive intraoperative cultures of specimens of periprosthetic tissue obtained during a revision total knee arthroplasty performed because of presumed aseptic loosening. The patients were managed according to one of four protocols. Five infections in five patients who had positive intraoperative cultures were treated with antibiotic therapy alone. Twenty-three early postoperative infections in twenty-one patients were treated with débridement, antibiotic therapy, and retention of the prosthesis. Twenty-nine late chronic infections in twenty-eight patients were treated with a delayed-exchange arthroplasty after a course of antibiotics. Seven acute hematogenous infections in six patients were treated with débridement, antibiotic therapy, and retention of the prosthesis. Seventeen infections in seventeen patients were not treated according to one of the four protocols. Sixteen late chronic infections were treated either with an arthrodesis (five infections) or with débridement, antibiotic therapy, and retention of the prosthesis (eleven infections). One acute hematogenous infection was treated with resection arthroplasty because of life-threatening sepsis. RESULTS: The mean duration of follow-up was 4.0 years (range, 0.3 to 14.0 years). Eleven patients who had an arthrodesis, a resection arthroplasty, or an above-the-knee amputation after less than two years of follow-up were included in the study as individuals who had a failure of treatment. In the group of patients who were managed according to protocol, the initial course of treatment was successful for all five infections that were diagnosed on the basis of positive intraoperative cultures, five of the ten deep early infections, all thirteen superficial early infections, twenty-four of the twenty-nine late chronic infections, and five of the seven acute hematogenous infections. Only one of eleven prostheses in patients who had a late chronic infection that was not treated according to protocol was successfully retained after débridement. CONCLUSIONS: Our treatment protocols, which were based on the clinical setting of the infection, were successful for most patients. A major factor associated with treatment failure was a compromised immune status. Bone loss and necrosis of the soft tissues around the joint also complicated the treatment of these infections.

Cementless acetabular revision for aseptic failure of cemented hip arthroplasty.

This study is a 5- to 11-year retrospective followup of 40 hips in 33 patients with cementless acetabular revision for aseptic failure of a cemented total hip arthroplasty. A porous coated, Harris-Galante acetabular component was used in all revisions. Thirty-eight of the 40 hips received acetabular bone grafting at revision. The mean Harris Hip Score improved from 51 points just before the index cementless revision to 87 points at the most recent followup. Twenty-nine of 40 (73%) hips were classified as having a good or excellent result. Radiolucencies were observed in seven of the 40 (18%) hips at the most recent followup, but none of these radiolucencies were complete or progressive. Five of the 40 (13%) hips were rated as failures and required repeat revision. Two (5%) of these failures were caused by aseptic loosening, with both hips having severe acetabular bone damage at the time of the index revision. This failure rate for aseptic loosening was less than that reported for cemented acetabular revision, thereby confirming the efficacy of cementless acetabular components in revision hip surgery in the intermediate term.

Clinical outcome of revision of the patellar component in total knee arthroplasty. A 2- to 7-year follow-up study.

The objectives of this study were to determine the relationship between the thickness of the residual patellar bone and the composite patella-patellar component, and the clinical outcome in patients who had undergone revision total knee arthroplasty (TKA) with a biconvex patellar component. Clinical outcome after at least a 2-year follow-up was determined using the Knee Society pain and functional scores, and radiographically, with the thicknesses of the patellar bone and composite measured in 23 knees (22 patients). The thickness of the patellar bone after preparation for a biconvex patellar component was significantly less for revised patellae (average, 5.0 mm) than the primary patellae (average, 7.9 mm; P < 0. 01). Differences in thickness between preoperative patellae, primary composites, and revision composites did not significantly affect postoperative results. There were no patellar fractures, despite the relatively thin bone remnant in the revision patients. Radiolucency was observed in 8% of the revisions. A patella with a thickness of residual bone of as little as 5 mm can provide favorable clinical results in revision TKA with restoration of the composite thickness of the patella achieved using a thick but small-diameter biconvex patellar component.

Treatment of congenital dislocated hip by arthroplasty with femoral shortening.

This was a retrospective study of 15 hips in 11 patients with complete congenital dislocation of the hip treated by total hip arthroplasty and femoral shortening with a subtrochanteric double chevron derotation osteotomy. The mean age at the time of surgery was 51 years (range, 21-74 years), and the mean followup was 5.5 years (range, 2-8.5 years). Functional evaluation using the modified Harris hip rating system showed an excellent result in five hips and a good result in seven hips (80% success rate). The location of the hip center was lowered by a mean of 8.3 cm (range, 5.7-10.4 cm). Leg length discrepancy in seven patients with unilateral involvement was reduced from a mean of 3.9 cm (range, 1.7-8.2 cm) before surgery to a mean of 1.4 cm at the latest followup (range, 0-4 cm). The Trendelenburg sign was assessed in 10 of 15 hips and was corrected from a positive preoperative status to a negative postoperative status in eight of these 10 hips. There were no cases of nonunion, dislocation, nerve palsy, or radiographic loosening. The only complications were a supracondylar fracture below the femoral component in a patient with severe osteoporosis 6 months after surgery and loosening of the cemented titanium metal backed acetabular component in the same patient 1.5 years after surgery. The current series showed that total hip arthroplasty in combination with a subtrochanteric double chevron derotation osteotomy has promising short to midterm results in the treatment of complete congenital dislocation of the hip in adults.

Soft tissue release in total knee arthroplasty. Cadaver study using knees without deformities.

Soft tissue releases are performed to correct fixed deformities in total knee arthroplasty. The goal of this in vitro study was to investigate the relationship between the individual steps in a medial (eight anatomic specimen knees) or lateral (four anatomic specimen knees) soft tissue release sequence, the resulting change in the medial and lateral tibiofemoral gaps, and the change in coronal angulation caused by 10 Nm varus and valgus moments in extension and 90 degrees flexion. An optical encoder was used to measure the coronal angulation. The tibiofemoral gaps were measured with calipers with the knee distracted by a 53-N load. In the medial release sequence, a significant increase in coronal angulation and medial gap occurred after the release of the anteromedial sleeve 8 cm from the medial joint line. In the lateral release sequence, there was a significant increase in the coronal angle and lateral gap after the lateral collateral ligament and popliteus tendon were released from the femur. Release of the posterior cruciate ligament led to a significant increase in angle and gap in medial and lateral release sequences. These results are specific for the particular release sequences studied, with release of the posterior cruciate being the final step in each sequence.

Gait analysis after total knee arthroplasty. Comparison of posterior cruciate retention and substitution.

: The objective of this study was to measure three-dimensional knee motion during gait in patients with total knee replacements which either retained the posterior cruciate ligament (n = 11), or required sacrifice of the posterior cruciate ligament and replacement of its function with a posterior stabilizing articular surface (n = 9). Clinically meaningful translations (anterior and posterior, medial and lateral, proximal and distal) and rotations (flexion and extension, internal and external rotation, abduction and adduction) were measured using an instrumented spatial linkage. Although patients from both groups were able to achieve passive full extension and a minimum of 95 degrees flexion, some of their translations and rotations during free speed walking were consistently less than those in a group of healthy controls. Motion during the swing phase of gait was similar for both knee replacement groups. However, abduction and adduction and proximal and distal translation were larger (but neither difference was significant) for the patients with implants with a posterior stabilizing surface, which suggests that the stabilizing surface may not reliably provide as much stability in these directions as does retention of the posterior cruciate ligament.

Update on the management of open fractures of the tibial shaft.

A retrospective study of 133 open tibial fractures in 129 patients treated at the Hennepin County Medical Center between 1986 and 1993 was done. The results of the treatment protocol in this patient group is presented and the current classification schemes, prevention of infection, debridement, antibiotics, soft tissue reconstruction, fracture stabilization methods, bone grafting, and exchange nailing are discussed. Recent studies that have documented interobserver disagreement in the classification of open fractures underscore the difficulties encountered in the initial assessment and treatment of open tibial shaft fractures. Despite repetitive and aggressive debridement, a certain number of fractures will remain contaminated and become infected. Infection after these severe injuries is probably multifactorial, and its prevention requires that the surgeon diligently adhere to the imperatives of open fracture care.

Prosthetic metals interfere with the functions of human osteoblast cells in vitro.

The release of metals from total joint prostheses may contribute to periprosthetic bone loss manifested as osteolysis. The effects of titanium, cobalt, and chromium on human osteogenic sarcoma cells (osteoblastlike cells) were investigated in vitro. Titanium, cobalt, and chromium at concentrations of 1, 10, and 100 ng/ml did not cause any changes in the cell growth, viability, and injury after 72-hour incubation with the cells. Titanium, cobalt, and chromium at concentrations ranging from 0.01 to 100 ng/ml significantly enhanced the release of interleukin-1 beta and tumor necrosis factor-alpha by lipopolysaccharide stimulated human osteogenic sarcoma cells, whereas they did not alter the release of transforming growth factor-beta 1. Cobalt at concentrations ranging from 0.1 to 100 ng/ml significantly enhanced the release of interleukin-6, but titanium and chromium did not. Cobalt and chromium at concentrations of 10 and 100 ng/ml significantly inhibited the release of osteocalcin by human osteogenic sarcoma cells, whereas titanium had no effect. Titanium, cobalt, and chromium at concentrations of 10 and 100 ng/ml significantly inhibited the synthesis of Type I collagen by human osteogenic sarcoma cells. Cobalt and chromium inhibited the cell proliferation in response to lipopolysaccharide stimulation, whereas titanium did not. The data presented in this article suggest that the metal induced disregulation of cytokine release and osteoblast dysfunction may play an important role in the induction of osteolysis in patients with total joint arthroplasties.

Prosthetic metals impair murine immune response and cytokine release in vivo and in vitro.

This study was designed to investigate whether prosthetic metals adversely affect immune responses and the release of immunoregulatory cytokines in vivo and in vitro. Titanium and cobalt-chromium alloy were injected into the peritoneal cavity of female mice. At 5, 8, and 12 weeks after the injection, the levels of cobalt and chromium in the blood were significantly increased compared with the levels in control mice; the level of titanium was not significantly changed until 12 weeks. The release of interleukin-2 was significantly inhibited by cobalt-chromium particles after 3 weeks; titanium particles did not have the same effect until 8 and 12 weeks. The release of interleukin-4 was significantly inhibited by cobalt-chromium particles after 3 weeks but was not significantly inhibited by titanium particles until 12 weeks. The release of interferon-gamma was significantly inhibited by cobalt-chromium particles only at 12 weeks and was not inhibited by titanium particles. The proliferation of T cells was significantly inhibited by cobalt-chromium particles at 3 weeks and by titanium particles at 8 and 12 weeks, and the proliferation of B cells was significantly inhibited by cobalt-chromium particles after 3 weeks but was not inhibited by titanium particles. The production of immunoglobulin by lipopolysaccharide-stimulated B cells was also significantly reduced by cobalt-chromium particles after 3 weeks and by titanium particles at 8 and 12 weeks. The cytokine release by lymphocytes, proliferation of T and B cells, and immunoglobulin production by B cells were also significantly inhibited by titanium and cobalt-chromium particles, as well as by titanium, cobalt, and chromium ions in vitro, whereas these metals are not cytotoxic to murine lymphocytes in vitro. The data indicate that the metal-induced immunosuppression may be another important factor in the development of implant-associated infection in patients with a prosthesis.

Inhibition of T and B cell proliferation by titanium, cobalt, and chromium: role of IL-2 and IL-6.

The mechanism by which an increased risk of prosthetic infection is induced in patients with total joint arthroplasties is poorly understood. The adverse effects of metallic corrosion products of a prosthesis on host defense mechanisms, particularly immune response and release of immunoregulatory cytokines, remain largely unknown. Titanium, cobalt, and chromium are the materials most often used for joint implantation. Therefore, this study was aimed at investigating the cytotoxicity of titanium, cobalt, and chromium and whether these metals affect T and B cell proliferation and the release of cytokines by human peripheral blood mononuclear cells (PBMC) in vitro. Metal cytotoxicity was not observed judging by cell viability and cell injury after PBMC was extensively exposed to the metals. Phytohemagglutinin (PHA)-induced T cell proliferation and lipopolysaccharide-induced B cell proliferation were significantly inhibited by titanium, chromium, and cobalt. The release of IL-2 and IL-6 by PHA-stimulated PBMC was significantly inhibited by titanium, chromium, and cobalt. Titanium did not alter IFN-gamma production, whereas chromium and cobalt significantly reduced IFN-gamma release by PHA-stimulated PBMC. The addition of IL-2 and IL-6 significantly restored the metal-induced inhibition of T cell and B cell proliferation, respectively. This study sheds light on how the metals impair immune response and cytokine release, suggesting that patients with an extensive exposure to the metals may develop immune dysfunctions. The compromised immune response induced by the metals might significantly contribute to an increased risk of infection in patients with joint prostheses.

Titanium, chromium and cobalt ions modulate the release of bone-associated cytokines by human monocytes/macrophages in vitro.

Osteolysis has become a major cause of aseptic loosening in total joint arthroplasty (TJA). Titanium, cobalt and chromium are commonly used in orthopaedic implants (e.g. joint prostheses). The release of bone-associated cytokines has been associated with the development of osteolysis in patients with prostheses. We evaluated the effects of these metals on the release of bone-associated cytokines (IL-1 beta, IL-6, TNF-alpha and TGF-beta 1) by human blood monocytes/macrophages and monocyte-like U937 cells upon lipopolysaccharide (LPS) stimulation, the cell proliferation, and their cytotoxic effects on these cells in vitro. We found that the release of IL-1 beta was enhanced by titanium, chromium and cobalt, the release of TNF-alpha was enhanced by titanium and chromium, and the release of IL-6 was enhanced by titanium. All three metal ions inhibited the release of TGF-beta 1. We also found that titanium and chromium, but not cobalt, enhanced blood monocyte/macrophage proliferation in response to LPS while only titanium enhanced U937 cell proliferation in response to LPS. The metals in concentrations ranging from 0.01 to 100 ngml-1 did not stimulate the cells to secrete detectable cytokines in the absence of LPS. Furthermore, a 4-h pre-exposure of blood monocytes/macrophages or U937 cells to the metals did not alter cytokine release when the metals were removed from the media prior to the addition of LPS. Similarly, a 4-h pre-exposure of blood monocytes/macrophages or U937 cells to LPS did not alter cytokine release when LPS was removed from the media prior to the addition of the metals. The metals did not reduce cell viability and induce cell injury after 72h incubation with the cells. The data suggest that the three metals at clinically relevant concentrations modulated cytokine expression, whereas they did not induce any cytotoxic effects. A metal-induced enhancement of bone-resorbing cytokine release with a concomitant inhibition of bone-forming cytokine release may be an important factor in the development of osteolysis, which can severely compromise the outcome of TJA.

Noncemented femoral components in total hip arthroplasty for patients with rheumatoid arthritis.

Twenty-seven patients with rheumatoid arthritis underwent cementless total hip arthroplasty from 1982 through 1989. We performed all operations through a posterior approach. Postoperatively, patient convalescence consisted of ambulation with crutches, followed by weight bearing as tolerated until pain and discomfort subsided. We contacted 25 (92.5%) patients for follow-up. Combined, these patients received 34 total hip arthroplasties. The patients ranged in age from 14 to 69 years old with a mean age of 42.9 years. The follow-up period ranged from two to eight years with a mean of five and one-half years. The mean preoperative total Harris hip score was 48 (range 31-68). The mean total Harris hip score at latest follow-up was 80 (range 44-95). Hip pain status and functional ability were important indicators of treatment efficacy. The lower incidence of pain, as well as the increase in functional abilities experienced by the patients, suggests that cementless total hip arthroplasty is a preferable alternative to fixed arthroplasty in patients with rheumatoid arthritis.

Infection after total hip arthroplasty. A study of the treatment of one hundred and six infections.

We evaluated the results of treatment for ninety-seven patients (106 infections in ninety-eight hips) who had had either an infection after a total hip arthroplasty or positive intraoperative cultures of specimens obtained during revision of a total hip arthroplasty for presumed aseptic loosening. The patients were managed according to various protocols on the basis of the clinical setting (positive intraoperative cultures, early postoperative infection, late chronic infection, or acute hematogenous infection). Aerobic gram-positive cocci accounted for 109 (74 per cent) of the 147 microbial isolates; gram-negative bacilli, for twenty-one (14 per cent); and anaerobes, for twelve (8 per cent). The white blood-cell count and erythrocyte sedimentation rate were elevated in association with seventeen (16 per cent) and sixty-seven (63 per cent) of the 106 infections, respectively. The mean duration of follow-up was 3.8 years (range, 0.3 to eleven years). A good result was noted after the initial treatment of twenty-eight (90 per cent) of the thirty-one infections that had been diagnosed on the basis of positive intraoperative cultures at the time of the revision, twenty-five (71 per cent) of the thirty-five early postoperative infections, twenty-nine (85 per cent) of the thirty-four late chronic infections, and three of the six acute hematogenous infections. Of the twenty++-one infections for which the initial therapy failed, twelve eventually were eradicated after additional treatment and the hip had a functional prosthesis at the time of follow-up. Of the ninety-seven infections that were treated successfully (there was a functional retained or exchange prosthesis in place at the time of the most recent follow-up and infection had not recurred at least two years after the discontinuation of antibiotic therapy), nine were associated with subsequent aseptic loosening of the prosthesis. The factors associated with recurrent infection were retained bone cement, the number of previous operations, potential immunocompromise, and early postoperative infection after arthroplasty without cement.

Long-term results of 56 revision total knee replacements.

Fifty-six consecutive revised total knee arthroplasties (TKA) were followed for an average of 8.3 years (range: 3 to 15 years). The purpose of this study was to evaluate the results of revision TKA to determine any trends in either the good outcomes or the failures. We found that the success rate for revision TKA was comparable to that for primary TKA. Eighty-nine percent of the knees rated at least fair, with 73% of these rating good or excellent, and 4% poor result. Moreover, the findings suggest that if prostheses are aligned correctly at implantation, there is only slight deterioration in their performance over time. Outcome was not affected by the type of prosthesis used in either the previous surgery or the revision. There is a correlation between the number of revisions and the functional knee rating; the more revisions, the less chance for success. There was also a direct correlation between varus knee alignment and significant increased incidence of failure. No appreciable difference was found between degenerative arthritis patients and rheumatoid patients, except that the rheumatoid patients had a higher incidence of delayed infections.

Extramedullary versus intramedullary alignment guides in total knee arthroplasty.

Use of extramedullary and intramedullary guides to prepare the tibia was studied comparatively in 100 consecutive primary total knee arthroplasties done by a single surgeon. Each type of guide was used in 50 consecutive cases, for a total of 100 cases. In all cases, an intramedullary guide was used to prepare the distal femur. Long (hip to ankle) anteroposterior radiographs were taken postoperatively to measure the mechanical angle, tibial component angle, femoral component angle, physiologic valgus angle, and tibiofemoral angle. No significant differences between the extramedullary and intramedullary groups were found; each system allowed satisfactory alignment. It is important for the surgeon to appreciate the benefits and deficiencies of each guide and to use whichever is suited most properly in each particular case.

Are cementless acetabular components the cause of excess wear and osteolysis in total hip arthroplasty?

The authors reviewed 175 primary cementless Biologic Ingrowth Anatomic System stem total hip arthroplasties with average followup of 7 years for wear and osteolysis. Group I (24 hips: fixed titanium heads, cemented polyethylene cups) had a wear rate of 0.10 mm per year, and lysis of 0%. Group II (62 hips: fixed titanium heads, cemented metal-backed cups) had a wear rate of 0.13 mm per year, and lysis of 31%. Group III (15 hips: fixed titanium heads, cementless cups) had a wear rate of 0.25 mm per year, and lysis of 87%. Group IV (74 hips: modular cobalt chromium heads, cementless cups) had a wear rate of 0.17 mm per year, and lysis of 24%. Wear rate was associated with younger age and male patients, but not polyethylene thickness. Age, gender, weight, and component stability had no effect on osteolysis rates. Group III had the statistically highest osteolysis rate. Group I had the statistically lowest osteolysis rate. Therefore, features of cementless acetabular cups, such as the screw holes, roughness of the metal shell, and locking mechanism, may cause increased wear and osteolysis.

Double-chevron subtrochanteric shortening derotational femoral osteotomy combined with total hip arthroplasty for the treatment of complete congenital dislocation of the hip in the adult. Preliminary report and description of a new surgical technique.

Total hip arthroplasty for the treatment of complete congenital dislocation of the hip in the adult has been associated with high rates of complications, including acetabular component loosening, femoral or sciatic nerve palsy, and prosthetic dislocation. Placement of the acetabular component in the true acetabulum has yielded the most durable results, but leads to significant limb lengthening, which is associated with sciatic and femoral nerve palsy. Femoral shortening with a transverse osteotomy tends to be torsionally unstable. Increased femoral anteversion complicates femoral component placement and, if not corrected, can lead to postoperative anterior instability and component dislocation. A new surgical technique that combines total hip arthroplasty with a femoral subtrochanteric shortening derotational double-chevron osteotomy in complete congenital hip dislocation using standard components is described. This procedure has been successfully performed in seven hips.