Clement B. Sledge

Outcomes of total hip and knee replacement: Preoperative functional status predicts outcomes at six months after surgery

OBJECTIVE To determine whether patients with knee or hip osteoarthritis (OA) who have worse physical function preoperatively achieve a postoperative status that is similar to that of patients with better preoperative function. METHODS This study surveyed an observational cohort of 379 consecutive patients with definite OA who were without other inflammatory joint diseases and were undergoing either total hip or knee replacement in a US (Boston) and a Canadian (Montreal) referral center. Questionnaires on health status (the Short Form 36 and Western Ontario and McMaster Universities Osteoarthritis Index) were administered preoperatively and at 3 and 6 months postoperatively. Physical function and pain due to OA were deemed the most significant outcomes to study. RESULTS Two hundred twenty-two patients returned their questionnaires. Patients in the 2 centers were comparable in age, sex, time to surgery, and proportion of hip/knee surgery. The Boston group had more education, lower comorbidity, and more cemented knee prostheses. Patients undergoing hip or knee replacement in Montreal had lower preoperative physical function and more pain than their Boston counterparts. In patients with lower preoperative physical function, function and pain were not improved postoperatively to the level achieved by those with higher preoperative function. This was most striking in patients undergoing total knee replacement. CONCLUSION Surgery performed later in the natural history of functional decline due to OA of the knee, and possibly of the hip, results in worse postoperative functional status.

Hip fracture mortality: relation to age, treatment, preoperative Illness, time of surgery, and complications

This retrospective analysis of 406 patients with proximal femoral fractures was designed to identify both the significant and nonsignificant risk factors that influence patient mortality. The 399 patients treated by open reduction and internal fixation or femoral head prostheses routinely received prophylactic antibiotics and anticoagulants. Of 406 patients followed until death or for at least one year, the overall mortality rate at one year was 14% (58/406). For patients with subcapital fractures the rate was 13% (25/187) and with intertrochanteric fractures 15% (33/219). The expected mortality rate for the normal population of similar age was about 9%. Sex, treatment of subcapital fracture by either internal fixation or arthroplasty, and the level of postoperative ambulation did not influence mortality. The number of preexisting medical conditions and the time of surgery following admission were highly significant factors (p less than or equal to 0.001 for both). The number of postoperative medical complications was also significant. The recommendation is for serious medical conditions to be maximally stabilized for at least 24 hours and pulmonary and physical therapy instituted before scheduling open surgical procedures.

Matrix collagen type and pore size influence behaviour of seeded canine chondrocytes

This study directly compared the behaviour of chondrocytes in porous matrices comprising different collagen types and different pore diameters. There was a dramatic difference in the morphology of the cells in the type I and type II collagen matrices. The cells in the type II collagen matrix retained their chondrocytic morphology and synthesized glycosaminoglycans, while in the type I matrix the chondrocytes displayed a fibroblastic morphology with less biosynthetic activity than those in the type II. Small pore diameter affected morphology initially in the type I matrices and showed a higher increase of DNA content, but with time the cells lost the chondrocytic morphology. Our results demonstrate the marked influence of collagen type and pore characteristics on the phenotypic expression of seeded chondrocytes.

Effect of Cultured Autologous Chondrocytes on Repair of Chondral Defects in a Canine Model

Articular cartilage has a limited capacity for repair. In recent clinical and animal experiments, investigators have attempted to elicit the repair of defects of articular cartilage by injecting cultured autologous chondrocytes under a periosteal flap (a layer of periosteum). The objective of the present study was to determine the effect of cultured autologous chondrocytes on healing in an adult canine model with use of histomorphometric methods to assess the degree of repair. A total of forty-four four-millimeter-diameter circular defects were created down to the zone of calcified cartilage in the articular cartilage of the trochlear groove of the distal part of the femur in fourteen dogs. The morphology and characteristics of the original defects were defined in an additional six freshly created defects in three other dogs. Some residual non-calcified articular cartilage, occupying approximately 2 per cent of the total cross-sectional area of the defect, was sometimes left in the defect. The procedure sometimes damaged the calcified cartilage, resulting in occasional microfractures or larger fractures, thinning of the zone of calcified cartilage, or, rarely, small localized penetrations into subchondral bone. The forty-four defects were divided into three treatment groups. In one group, cultured autologous chondrocytes were implanted under a periosteal flap. In the second group, the defect was covered with a periosteal flap but no autologous chondrocytes were implanted. In the third group (the control group), the defects were left empty. The defects were analyzed after twelve or eighteen months of healing. Histomorphometric measurements were made of the percentage of the total area of the defect that became filled with repair tissue, the types of tissue that filled the defect, and the integration of the repair tissue with the adjacent cartilage at the sides of the defects and with the calcified cartilage at the base of the defect. In histological sections made through the center of the defects in the three groups, the area of the defect that filled with new repair tissue ranged from a mean total value of 36 to 76 per cent, with 10 to 23 per cent of the total area consisting of hyaline cartilage. Integration of the repair tissue with the adjacent cartilage at the edges of the defect ranged from 16 to 32 per cent in the three groups. Bonding between the repair tissue and the calcified cartilage at the base of the defect ranged from 41 to 89 per cent. With the numbers available, we could detect no significant difference among the three groups with regard to any of the parameters used to assess the quality of the repair. In the two groups in which a periosteal flap was sutured to the articular cartilage surrounding the defect, the articular cartilage showed degenerative changes that appeared to be related to that suturing. CLINICAL RELEVANCE: The technique of injecting cultured autologous chondrocytes under a periosteal flap recently was introduced to treat defects in the articular cartilage of humans. The long-term efficacy of this treatment is unknown. An animal model was developed to evaluate the procedure and its effectiveness.

Long-term complications after total knee arthroplasty with or without resurfacing of the patella.

The long-term complications related to the patella were retrospectively evaluated for 891 knees (684 patients) that had had a total arthroplasty, with or without resurfacing of the patella, with use of an unconstrained, condylar, posterior-cruciate-preserving prosthesis. The study population comprised two groups of patients who were similar in size, age, sex distribution, and diagnosis. One group (396 knees [303 patients]) had had a total knee arthroplasty with patellar resurfacing and the other group (495 knees [381 patients]) had had the same procedure without resurfacing. The average duration of follow-up was six and one-half years (range, two to fifteen years). The decision to resurface the patella was based on subjective inspection of the articular surface and on assessment of patellar tracking at the time of the operation. Resurfacing was performed if there was loss of cartilage, exposed bone, gross surface irregularities, or tracking abnormalities. Complications occurred an average of three years (range, immediately postoperatively to nine years) after the operation in the group that had had resurfacing and an average of four years (range, immediately post-operatively to ten years) postoperatively in the group that had not had resurfacing. In the group that had had resurfacing, there was loosening of the patellar component in five knees, patellar subluxation in four knees, fracture of the patella in three knees, rupture of the patellar tendon in three knees, and chronic peripatellar pain in one knee. In the group that had not had resurfacing, the complications included patellar subluxation in five knees, rupture of the patellar tendon in two knees, and chronic peripatellar pain in fifty-one knees.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors influencing the incidence and outcome of infection following total joint arthroplasty.

During a ten-year period, 4240 total hip, knee, and elbow arthroplasties were performed. The overall infection rate was 1.25%. Certain groups were identified as being at higher risk of infection following total joint arthroplasty: rheumatoid arthritics were at 2.6 times greater risk than osteoarthritics; patients undergoing total hip arthroplasty as a revision of a previous operation were eight times more likely to have infection than those undergoing a primary operation; and patients with metal-to-metal hinged knee prostheses, when compared with patients with metal-to-plastic knee prostheses, were 20 times more likely to have infection. The majority of infections could be attributed either to perioperative problems or late bacterial seeding from a distant site. Although most infections occurred by two years after operation, late infections, particularly in rheumatoid patients via the hematogenous route, occurred as long as nine years after operation. There was no correlation between the Grams-staining characteristics of the pathogen and the outcome of the infected joint. Gram-negative organisms were frequent in the perioperative period and reflected either nosocomial infection or the ineffectiveness of the prophylactic antibiotic regimen used in inhibiting gram-negative pathogens. The major factors that influenced the outcome of the infected joint included the interval from the initial surgery to recognition of infection, the delay in institution of appropriate treatment, the particular joint that was infected, the integrity of the bone-cement interface, the type of prosthesis used, and the host susceptibility. Identification of high-risk groups and the recognition that patients with joint implants are at risk of infection at any time in the postoperative period may lead to a lowered infection rate in the future.

The weight-bearing shoulder. The impingement syndrome in paraplegics.

The cases of ninety-four patients who had complete paraplegia were studied to determine whether they had complaints about the shoulder during transfer activities. Thirty-one patients reported pain on transferring, and twenty-three of these patients were found to have a chronic impingement syndrome with subacromial bursitis. Arthrography of the shoulder was done for each of these twenty-three patients, and fifteen were found to have a tear of the rotator cuff. Five of the thirty-one patients were found to have aseptic necrosis of the head of the humerus. We also measured the intra-articular pressure in the shoulder in five patients during different activities, including transfer from wheelchair to bed, and found that this pressure exceeded the arterial pressure by two and one-half times. We believe that this high pressure, in conjunction with abnormal distribution of stress transmitted across the subacromial area during transfer or propulsion of a wheelchair, contributes to the high rate of problems about the shoulder in paraplegics.

Canine chondrocytes seeded in type I and type II collagen implants investigated In Vitro

Synthetic and natural absorbable polymers have been used as vehicles for implantation of cells into cartilage defects to promote regeneration of the articular joint surface. Implants should provide a pore structure that allows cell adhesion and growth, and not provoke inflammation or toxicity when implanted in vivo. The scaffold should be absorbable and the degradation should match the rate of tissue regeneration. To facilitate cartilage repair the chemical structure and pore architecture of the matrix should allow the seeded cells to maintain the chondrocytic phenotype, characterized by synthesis of cartilage-specific proteins. We investigated the behavior of canine chondrocytes in two spongelike matrices in vitro: a collagen-glycosaminoglycan (GAG) copolymer produced from bovine hide consisting of type I collagen and a porous scaffold made of type II collagen by extraction of porcine cartilage. Canine chondrocytes were seeded on both types of matrices and cultured for 3 h, 7 days, and 14 days. The histology of chondrocyte-seeded implants showed a significantly higher percentage of cells with spherical morphology, consistent with chondrocytic morphology, in the type II sponge at each time point. Pericellular matrix stained for proteoglycans and for type II collagen after 14 days. Biochemical analysis of the cell seeded sponges for GAG and DNA content showed increases with time. At day 14 there was a significantly higher amount of DNA and GAG in the type II matrix. This is the first study that directly compares the behavior of chondrocytes in type I and type II collagen matrices. The type II matrix may be of value as a vehicle for chondrocyte implantation on the basis of the higher percentage of chondrocytes retaining spherical morphology and greater biosynthetic activity that was reflected in the greater increase of GAG content.

Validity and Responsiveness of the Knee Society Clinical Rating System in Comparison with the Sf-36 and Womac

Background: The aim of this study was to validate the Knee Society Clinical Rating System (knee and function scores) and to compare its responsiveness with that of the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and the Medical Outcomes Study Short Form-36 (SF-36). Methods: Patients were recruited as part of a prospective observational study of the outcomes of primary total knee arthroplasty for the treatment of osteoarthritis in four centers in the United States, six centers in the United Kingdom, and two centers in Australia. Independent research assistants at each site collected the Knee Society clinical data. The WOMAC, SF-36, patient satisfaction, and demographic data were obtained with self-administered questionnaires. Results: A total of 862 eligible patients were recruited, and complete preoperative and twelve-month data were available for 697 (80.9%) of them. The mean age was seventy years (range, thirty-eight to ninety years), and the majority of the patients (58.9%) were women. Low correlations were found among the items of both the knee and the function score at both assessment times. The Knee Society pain and function scores had moderate-to-strong correlations with the corresponding pain and function domains of the WOMAC and SF-36 (r = 0.31 to 0.72). Measurement of the standardized response mean showed the Knee Society knee score to be more responsive (standardized response mean, 2.2) than the WOMAC (standardized response means, 2.0 for pain and 1.4 for function) and the SF-36 (standardized response means, 1.0 for bodily pain and 1.1 for physical functioning). The Knee Society function score was the least responsive measure (standardized response mean, 0.8). Correlation of changes in scores at twelve months with patient reports of satisfaction and improvement in health status showed the WOMAC and SF-36 to be more responsive than the Knee Society scores. Conclusions: There is a poor correlation among the items of the Knee Society Clinical Rating System, but the rating system has adequate convergent construct validity. The WOMAC and SF-36 are more responsive measures of outcome of total knee arthroplasty. As they are less labor-intensive for researchers to use and as use of these instruments removes observer bias from the study design, they are preferable for knee arthroplasty outcome studies.

Long-term results of revision total hip replacement. A follow-up report.

The results of 110 revision total hip replacements performed for aseptic failure, with an average follow-up of 3.4 years, were reported in 1982. We were able to continue to follow ninety-nine of these patients for an average of 8.1 years (range, five to 12.5 years). With this longer follow-up, we found that twenty-nine (29 per cent) of these revised arthroplasties have since failed. Most of the failures after 1982 occurred in the hips that were known to have a progressive radiolucency at the time of the first evaluation. We concluded that there is an increased failure rate with longer follow-up of revision total hip replacement, and that progressive radiolucency at an interface indicates a poor prognosis for the arthroplasty.