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Range of motion after total knee arthroplasty is an important variable in determining clinical outcome. The goal of this study was to assess range of motion across five types of posterior-stabilized knee prostheses used sequentially in the same institution during 17 years. The hypothesis was that ab

The development, maintenance, and destruction of cartilage are regulated by mechanical factors throughout life. Mechanical cues in the cartilage fetal endoskeleton influence the expression of genes that guide the processes of growth, vascular invasion, and ossification. Intermittent fluid pressure maintains the cartilage phenotype whereas mild tension (or shear) promotes growth and ossification. The articular cartilage thickness is determined by the position at which the subchondral growth front stabilizes. In mature joints, cartilage is thickest and healthiest where the contact pressure and cartilage fluid pressure are greatest. The depth-dependent histomorphology reflects the local fluid pressure, tensile strain, and fluid exudation. Osteoarthritis represents the final demise and loss of cartilage in the skeletal elements. The initiation and progression of osteoarthritis can follow many pathways and can be promoted by mechanical factors including: (1) reduced loading, which activates the subchondral growth front by reducing fluid pressure; (2) blunt impact, causing microdamage and activation of the subchondral growth front by local shear stress; (3) mechanical abnormalities that increase wear at the articulating surface; and (4) other mechanically related factors. Research should be directed at integrating our mechanical understanding of osteoarthritis pathogenesis and progression within the framework of cellular and molecular events throughout ontogeny.

The treatment of osteoarthritis includes a wide spectrum of approaches. This article reviews current practices in medical, pharmaceutical and surgical treatment with a perspective toward the immediate, distant and far distant future. At present, with the exception of surgery, all other treatments ar

Patients with anterior cruciate ligament instability resulting from incomplete tears or elongation in continuity without ligament detachment historically have been treated conservatively or by graft replacement. The literature is sparse regarding alternative treatments. The current study presents experience using monopolar thermal repair on 28 consecutive knees with partial anterior cruciate ligament tears all symptomatically unstable. All lesions were less than 6 months old (average, 77 days; range, 7-180 days) and with a difference of 6 mm or more (average, 9 mm; range, 6-13 mm) when comparing both knees using KT-1000 evaluation. Incomplete tears of the anterior cruciate ligament were seen at arthroscopic evaluation. The rehabilitation protocol included use of a brace for at least 6 weeks and progressive weightbearing. A 2-year minimum followup (range, 24-35 months) was done in all patients following the International Knee Documentation Committee guidelines. The overall outcome was normal or nearly normal in 96% of the patients. One failure occurred at 8 weeks. Twenty-six knees had a KT-1000 difference between 0 and 2 mm (average, 1.9 mm). Because thermal application causes death to some of the cells directly treated, it should be taken into account in selection and application. Immediately after thermal use, the anterior cruciate ligament, although thicker and tighter, is at first weaker than normal. Rehabilitation and compliance are critical during early ligament healing. This procedure seems to be a reasonable alternative to anterior cruciate ligament grafting in selected patients.

A review of postoperative infected anterior cruciate ligament reconstructions was done on 3500 consecutive arthroscopic procedures. The purpose was to assess incidence, diagnosis, treatment, and outcome factors. Six postoperative in-traarticular infections were detected. Average followup was 3 years (range, 2-8 years). The rate of infection was 0.14%. Five men and one woman with a median age of 32.5 years (range, 20-51 years) comprised the study group. The average interval from the onset of symptoms to the initial arthroscopic intervention was 7.5 days (range, 2-20 days). Staphylococcus aureus was present in three knees, Staphylococcus epidermidis in two, and Streptococcus nonhemolytic in one. All patients had initial arthroscopic debridement and lavage followed by 6 weeks of intravenous antibiotics. Two grafts were removed: one patient had delayed ligament reconstruction and the other had total knee arthroplasty. The remaining patients had full range of motion. In the group with the best result, two patients had Staphylococcus epidermidis and one had Staphylococcus aureus, which was treated 2 days after clinical symptoms began. The other two patients infected with Staphylococcus aureus had unsatisfactory results. Anterior cruciate ligament infection is rare, but diagnosable. When treated early with appropriate antibiotic therapy and arthroscopic debridement, four of six grafts were retained. If the infection does not respond rapidly to early therapy, then graft removal is an option.

Background: Loosening of the implant after total joint arthroplasty remains a serious problem. The activation of macrophages by wear debris from implants, mediated by the release of cytokines that elicit bone resorption, may lead to loosening. The purpose of the present study was to elucidate the mechanisms of macrophage activation by titanium particles from the components of implants and to identify the signaling pathways involved in particle-mediated release of cytokines. Methods: Macrophages were isolated from mononuclear leukocytes obtained from healthy human donors and were exposed to titanium-alloy particles that had been obtained from periprosthetic membranes collected at revision total joint arthroplasties and then enzymatically prepared. The experimental protocols included examination of the effects of the inhibition of phagocytosis and the binding of antibodies to macrophage complement receptors on particle-induced macrophage activation. The release of the proinflammatory cytokines TNF-α (tumor necrosis factor-alpha) and IL-6 (interleukin-6) was used to assess macrophage activation. The signaling pathways involved in the induction of cytokine release were analyzed by identification of phosphorylated proteins with use of the Western blot technique and by translocation of the transcription factors nuclear factor-kappa B (NF-κB) and nuclear factor-interleukin-6 (NF-IL-6) into the nuclear protein fraction with use of electrophoretic mobility shift assays. The role of serine/threonine and tyrosine kinase pathways in the activation of nuclear factors and the release of cytokines was examined with use of selective pharmacological agents. Results: Exposure of macrophages to titanium-alloy particles in vitro for forty-eight hours resulted in a fortyfold increase in the release of TNF-α and a sevenfold increase in the release of IL-6 (p < 0.01). Phagocytosis of particles occurred in approximately 73 percent of the macrophages within one hour of exposure. Pretreatment of the macrophages with cytochalasin B reduced phagocytosis by 95 percent but did not reduce the release of TNF-α or IL-6. Thus, phagocytosis of particles was not necessary for induction of the release of TNF-α or IL-6 in the cultured macrophages. Ligation of the macrophage CD11b/CD18 receptors by integrin-specific antibodies also increased the release of TNF-α and IL-6. Antibodies to CD11b/CD18 receptors (macrophage Mac-1 receptors) reduced phagocytosis of particles by 50 percent (p < 0.05). (The CD11b/CD18 macrophage receptor is the macrophage receptor for the complement component CR3bi. The CD11b/CD18 macrophage receptor can also bind to ICAM-1 and ICAM-2. CD is the abbreviation for cluster of differentiation, and ICAM is the abbreviation for intercellular adhesion molecule.) Inhibition of phagocytosis was not accompanied by a decrease in the release of TNF-α and IL-6. Blocking RNA synthesis with actinomycin D or preventing protein synthesis with cycloheximide abolished or decreased particle-induced release of TNF-α and IL-6 from the macrophages. Macrophage release of TNF-α and IL-6 in response to particles coincided with increased tyrosine phosphorylation and mitogen-activated protein kinase activation. Inhibition of tyrosine and serine/threonine kinase activity decreased the particle-induced release of cytokines. Exposure of macrophages to either titanium-alloy particles or to antibodies to the receptor proteins CD11b and CD18 for thirty minutes activated the transcription factors NF-κB and NF-IL-6. Inhibition of particle phagocytosis did not block activation of the transcription factors. However, inhibition of tyrosine and serine/threonine kinase activity decreased the activation of NF-κB and NF-IL-6. Conclusions: These data suggest that particle-induced macrophage release of TNF-α and IL-6 does not require phagocytosis but is dependent on tyrosine and serine/threonine kinase activity culminating in activation of the transcription factors NF-κB and NF-IL-6. Clinical Relevance: Retrieval studies have documented numerous macrophages in association with particulate debris in granulomatous tissue surrounding failed total joint replacements. However, the molecular basis on which wear particles induce macrophage expression of proinflammatory cytokines and bone-resorbing factors remains unclear. This in vitro study showed that particles incite the release of proinflammatory cytokines from macrophages in the absence of phagocytosis. These results imply that contact of wear particles with macrophage cell-surface membrane proteins, such as the complement receptor CD11b/CD18, is sufficient signal for release of proinflammatory cytokines. The data further suggest that release of proinflammatory cytokines follows transmission of a membrane recognition event through intracellular signaling pathways that effect gene activation and protein synthesis. Therefore, these data indicate that a reduction in the formation of wear particles can be expected to improve the outcome after total joint arthroplasty by decreasing macrophage activation.

Postoperative knee flexion in patients undergoing Insall-Burstein-II total knee arthroplasty at 2 years was evaluated regarding two basic questions: what groups of patients gain or lose the most flexion and what groups of patients have the best or worst postoperative flexion. Thirteen preoperative variables (maximum flexion, flexion arc, tibiofemoral angle, quadriceps strength, extensor lag, Knee Society score, Knee Society patient assessment, gender, age, height, weight, diagnosis, and surgeon) and four postoperative variable (leg length change, tibiofemoral angle, distance from patella to the joint line, and the tibial prosthesis anteroposterior translation on a lateral radiograph) were used in an attempt to explain postoperative flexion. The analysis was performed on 164 consecutive Insall-Burstein-II total knees in which the data were gathered prospectively on a time oriented medical record database. A regression tree analysis was used to identify several groups of patients, characterized by preoperative factor values, who had markedly above average performance on postoperative flexion. The preoperative factors identified include preoperative flexion, flexion arc, tibiofemoral angle, extensor lag, diagnosis, and age. The only postoperative variable of significance was tibiofemoral angle. Among the potential determinants of postoperative flexion that failed to appear predictive were the Knee Society scores and surgeon. Preoperative flexion is known to be a critical determinant of postoperative flexion in total knee replacement. However, in the current study, preoperative flexion accounted for only half of the difference between the best (122 degrees) and the worst (88 degrees) group, as determined with regression tree analysis.

The purpose of this study was to characterize the cell types (using immunohistochemistry) and cytokine expression (using in situ hybridization) of tissues surrounding well fixed and loose cemented prostheses undergoing revision. Clinical and radiographic data were gathered prospectively for a series of cemented total joint replacements undergoing revision. Three groups were identified: (1) loose implants with osteolysis (10 specimens), (2) loose implants without osteolysis (11 specimens), and (3) well fixed implants (7 specimens). At surgery, a specimen was harvested from the bone cement interface. Immunohistochemical staining was performed using monoclonal antibodies to identify macrophages and lymphocyte subgroups. Human antisense probes were selected to identify the mRNA for specific cytokines using in situ hybridization. The percentage of positively staining cells was determined for each antibody or probe using a grid counting technique. Tissues from loose cemented prostheses with osteolysis contained significantly greater numbers of macrophages and T lymphocytes compared with tissues from loose and well fixed cemented prostheses without osteolysis. The number of interleukin-1 and interleukin-6 positive cells was highest in specimens with osteolysis and lowest in specimens from well fixed prostheses. These cytokines modulate the growth and differentiation of cells in the immune system and the monocyte and macrophage system and mediate the remodeling of bone and mesenchymal tissues. Specific cell populations and cytokine profiles appear to be involved in periprosthetic osteolysis; this information may be useful in planning strategies for prevention and treatment.

The pneumatic tourniquet produces ischemic changes in limbs. The effects of tourniquet release on systemic blood pressure and metabolic parameters were studied in 11 adult patients undergoing total knee replacement under general anesthesia. Mean arterial pressure (MAP) decreased rapidly after the release of the tourniquet, becoming significant at 3 min and remaining significantly depressed up to 15 min post release. Arterial pH, PaO2, PaCO2, lactate acid, and potassium changed significantly after the release, but normalized within 30 min. These results are notably different from a previous study in a similar patient population undergoing knee replacement under epidural anesthesia. Compared to patients under epidural anesthesia, patients receiving general anesthesia with mechanical ventilation are unable to compensate for the metabolic load caused by the tourniquet release, as the latter group are unable to alter their ventilatory rate. In elderly patients with decreased cardio-pulmonary reserve, this may be of clinical importance.

This report presents a method for analyzing matrix metalloproteinase-9 (92 kD gelatinase) MMP-9 mRNA expression using reverse transcription polymerase chain reaction (RT-PCR). With this method, chondrocytes isolated from small samples of osteoarthritic cartilage showed significantly elevated signal for MMP-9 mRNA compared to normal cartilage. In addition, cells of synovial fluid samples aspirated from osteoarthritic joints also exhibited MMP-9 expression using this technique. RT-PCR proved to be a sensitive method for assessing MMP-9 regulation in osteoarthritic and normal cartilage, and may provide a useful index of arthritic cartilage and synovial fluid cell metabolism when limited tissue is available.

The purpose of this study was to examine the effects of particles, derived from metals commonly used in joint prostheses, on chondrocyte proliferation, metabolism, and morphology in vitro. Chondrocyte viability was influenced by the type and concentration of metal particle added. Cobalt was toxic to chondrocytes at all particle concentrations (0.83–0.000083%, v/v), whereas the chromium, titanium and titanium-aluminum particles only effected chondrocyte viability at high concentrations. The metabolic response of chondrocytes to particulate debris as assessed by caseinase, collagenase, and hexosaminidase activities were variable at low concentrations but were always reduced at high concentrations (0.83% v/v). Prostaglandin E2 levels in the medium showed a steady increase when particle load increased, except in the medium of chondrocytes exposed to titanium-aluminum. Scanning electron microscopy of chondrocytes exposed to titanium showed ruffled cell borders and frequent membrane blebbings. This was in contrast to chondrocytes exposed to cobalt, where the crenated appearance indicated cell death, and titanium-aluminum, where the cells appeared quiescent. These findings show that metal particles alter chondrocyte viability and metabolism and suggest that particulate debris may influence the integrity and stability of articular cartilage following hemiarthroplasty. © 1994 John Wiley & Sons, Inc.

Bovine synovial fibroblasts in primary monolayer culture were exposed to particulate metallic debris. The effects of the metallic particles on the synthesis and secretion of proteolytic enzymes and on cell proliferation and viability were examined. Uniform suspensions of titanium, titanium-aluminum, cobalt, and chromium particles, ranging in size from approximately 0.1 to ten micrometers (average, one to three micrometers), were prepared; the particle concentrations (the volume of particles divided by the total volume of the suspension) ranged from 0.0005 to 5 per cent. Aliquots of the particle suspensions were added to the synovial fibroblast cultures. The final particle concentrations in the media ranged from 0.0000083 to 0.83 per cent. After seventy-two hours of exposure, each medium was harvested and was assayed for proteolytic and collagenolytic activity and for hexosaminidase levels. Neutral metalloproteases, quantified by collagenolytic and caseinolytic (proteolytic) activity, represent enzymes, secreted by cells, that are capable of degrading extracellular matrix. Hexosaminidase is a marker for lysosomal enzyme activity that can include more than thirty enzymes, such as proteases, lipases, nucleases, and phosphatases. Cell proliferation was quantified by uptake of 3H-thymidine. Cell morphology was examined by scanning electron microscopy. Titanium, titanium-aluminum, and chromium significantly stimulated 3H-thymidine uptake at low particle concentrations (p < 0.01, p < 0.002, and p < 0.002, respectively). Exposure to cobalt, even at the lowest particle concentration, resulted in a significant decrease in thymidine uptake (p = 0.027). At the highest particle concentrations, all particles were toxic, as evidenced by the absence of thymidine uptake. At high particle concentrations, all of the metals caused a decrease in caseinolytic (proteolytic) and collagenolytic activity in the culture media. Titanium elevated the lysosomal enzyme marker, hexosaminidase, except at high concentrations. Chromium and titanium-aluminum had no significant effect on hexosaminidase at any particle concentration, while cobalt decreased all enzyme markers at mid-particle to high-particle concentrations. Scanning electron microscopy demonstrated that the morphological response of fibroblasts to titanium included membrane-ruffling and extension of filopodia, typical of active fibroblasts. In contrast, exposure to cobalt at the same concentration resulted in cell crenation, indicative of cell death.

Matrix metalloproteinases are a family of endopeptidases that collectively degrade all components of the extracellular matrix at neutral pH. During the progression of arthritis, MMPs mediate the degradation of cartilage, which consists largely of Type II collagen fibrils and proteoglycans. The collagenases, a subgroup of MMPs, have the singular ability to cleave intact collagens and may provide a rate-limiting step in cartilage destruction. In arthritic lesions, collagenase-1 (matrix metalloproteinase-1) and collagenase-3 (matrix metalloproteinase-13) mediate the irreversible destruction of cartilage, suggesting that these enzymes are therapeutic targets. We describe the role of metalloproteinases in the destruction of connective tissues in arthritis and the treatment strategies that have been developed to block matrix metalloproteinases in an attempt to prevent this destruction. We also discuss novel compounds that may selectively inhibit these cartilage-degrading enzymes, providing opportunities to develop new therapeutic approaches.

Background: Primary total hip replacement performed through an incision that is ≤10 cm in length has been advocated as a minimally invasive technique. Proponents have claimed that mini-incision techniques reduce blood loss, transfusion requirements, postoperative pain, and the length of the hospital stay compared with standard techniques through a longer incision. However, we are aware of no well-designed comparison study that supports these claims. The purpose of the present study was to compare the short-term results of a mini-incision with a standard incision technique for total hip replacement. Methods: A consecutive series of patients who underwent 135 primary unilateral total hip replacements (fifty with use of a mini-incision [≤10 cm] and eighty-five with use of a standard incision) by three surgeons at one hospital were studied. Each surgeon selected patients to have a mini-incision procedure and performed a standard approach in the remaining patients. A posterior approach was used for all procedures. In-hospital data were collected retrospectively, and the initial postoperative radiographs were analyzed. Because of the selection process, the patients who had a mini-incision had both a significantly lower average body-mass index (p = 0.008) and a lower average score on the American Society of Anesthesiologists rating (p = 0.006), indicating that they were thinner and healthier than the patients who had a standard incision. Results: With the numbers of patients available, no significant differences were found between the groups with respect to the average surgical time, intraoperative blood loss, in-hospital transfusion rate, length of hospital stay, or the patients' disposition after discharge. The mini-incision group was found to have a significantly higher risk of a wound complication (p = 0.02), a higher percentage of acetabular component malposition (p = 0.04), and poor fit and fill of femoral components inserted without cement (p = 0.0036). Conclusions: There was no evidence that the mini-incision technique resulted in less bleeding or less trauma to the soft tissues of the hip, factors that would have produced a quicker recovery and a shorter hospital stay, than did the standard technique. The present study, which was based on the authors' initial experience with the mini-incision technique, failed to confirm the positive clinical outcomes reported by previous uncontrolled cohort studies, and the findings suggest that further analysis of this new technique is needed before it can be recommended for general use. Level of Evidence: Therapeutic study, Level III-2 (retrospective cohort study). See Instructions to Authors for a complete description of levels of evidence.

The outcome of total joint arthroplasty is determined by biological events at the bone-implant interface. Macrophages phagocytose implant or wear debris at the interface and release proinflammatory mediators such as interleukins 1 and 6, tumor necrosis factor-alpha, and prostaglandin E2. These mediators are thought to contribute to the resorption of periprosthetic bone. Previous studies of tissues harvested from the bone-implant interface of failed orthopaedic implants demonstrated a possible role for two other cytokines, granulocyte-macrophage colony-stimulating factor and interleukin-4. The present study examined the effects of in vitro challenge with polymethylmethacrylate particles on the expression of granulocyte-macrophage colony-stimulating factor by primary human monocytes/macrophages and the role of interleukin-4 in regulating this expression. The polymethylmethacrylate particles caused a dose-dependent release of granulocyte-macrophage colony-stimulating factor at 48 hours. This release was accompanied by increased expression of interleukins 6 and 1beta and tumor necrosis factor-alpha. Release of the lysosomal enzyme hexosaminidase also increased in response to the particles. Interleukin-4 inhibited the expression of granulocyte-macrophage colony-stimulating factor, interleukin-6, and tumor necrosis factor-alpha at 48 hours in a dose-dependent manner. The data presented in this study confirm the hypothesis that interleukin-4 downregulates particle-induced activation of macrophages, as demonstrated by the decreased release of proinflammatory mediators.

Alterations in the location of the hip center may change the lengths and moment arms of the muscles, and thereby affect their capacity to generate force and moment about the hip. This study demonstrates some of the differences between compensating and not compensating for changes in muscle length that arise from displacement of the hip center. A computer model was developed to estimate the maximum isometric moment generating capacity of the hip muscles under two conditions. In the compensated condition, the hip center was displaced, but the muscles were restored to their original lengths and orientations by altering proximal femoral geometry. In the uncompensated condition, femoral geometry remained constant; thus, muscle lengths and orientations changed with displacement of the hip center. The computer simulations showed large differences between the two conditions. For example, a 2-cm superior displacement of the hip center decreased the moment generating capacity of the hip abductors 18% with compensation and 49% without compensation. Similarly, a 1-cm medial displacement of the hip center increased the moment generating capacity of the abductors 17% with compensation, but decreased it 4% without compensation. In contrast, a 1-cm inferior displacement decreased the moment generating capacity of flexors 6% with compensation, but increased it 12% without compensation. The results presented here demonstrate that compensating for changes in muscle length can be important in terms of preserving the moment generating capacity of the muscles when the hip center is displaced superiorly and medially, but not when the hip center is displaced in the inferior direction.

Cement removal in revision total hip arthroplasty can be technically challenging. Traditional methods involve using a combination of chisels, power burrs, and drills, as well as windowing the femoral cortex to gain access to cement distally. These methods can be associated with femoral fracture or uncontrolled cortical perforation and bone loss. A new technique had been developed that permits segmental extraction of bone cement from the femoral canal. Fresh cement is introduced into the old cement mantle and a threaded rod is placed into the wet cement and held in place while the cement hardens

Range of motion (ROM) after total knee arthroplasty (TKA) is an important variable in determining clinical outcome. Recent design modifications have been aimed at improving final motion. The posterior stabilized total knee prosthesis was introduced as a modification of the total condylar design, changing the center of curvature of the femoral component to allow greater ROM. In this study, all primary TKAs performed at the authors' institution from July 1982 until December 1986 were reviewed to determine the effect of this design modification on outcome. A total condylar (TC) group comprised 51 arthroplasties and was compared to 53 arthroplasties in a posterior stabilized (PSTC) group. the postoperative protocol was identical in both groups. The mean postoperative flexion was 11 better in the PSTC group; however, the mean preoperative flexion had initially been 10 degrees better in the PSTC group. The maximum flexion achieved by any patient in both groups was similar, but the TC group actually gained slightly more arc of motion. The better motion in the PSTC group may be secondary to better motion preoperatively and not implant design in this series. The more limited the preoperative ROM, the greater the quadriceps stiffness is likely to be, which is an important determinant of postoperative flexion. Review of the literature supports present observations that a group with less mean preoperative motion paradoxically gains a slightly greater increment of flexion. Differences in flexion after TKA are difficult to attribute to design in either the current study or by a review of the literature. This is because determinants of flexion after TKA are multifactorial and outcome data limited, notwithstanding the similarities among modern prostheses.

The roles of physical activity (both work and leisure time), obesity, and history of significant knee injury on the development of severe osteoarthrosis (OA) of the knee were evaluated. A case-control design compared 46 cases with a history of severe OA of the knee with 46 community controls matched for age and gender. Data were gathered with a self-administered questionnaire. The OA cases were 3.5 times more likely than controls to have been obese at 20 years of age, two to three times more likely than controls to have performed heavy work, and almost five times more likely than controls to have had a significant knee injury. In contrast, leisure-time physical activity was not significantly different in cases compared with controls. Obesity, significant knee injury, and long-term heavy physical activity are important risk factors for the development of OA of the knee.

Can patients treated with total hip arthroplasty (THA) receive high-quality inpatient care at less cost? In 1984, a group of orthopedic surgeons and nurses examined the use of resources for THA patients and changed certain clinical practices to promote more cost-effective hospital care. At the end of the two-year project, orders for complete blood counts fell 72% and mean operating room time dropped 47 minutes for the participating orthopedists. For all orthopedists in the division, average length of stay (ALOS) decreased from 13 to 11 days. By the end of the following year, when clinicians received quarterly length-of-stay (LOS) data, ALOS dropped further to 9.8 days. This significant ALOS reduction was not accompanied by an increase in hospital readmissions or nursing home placements. The ALOS reduction was also not seen in elective coronary artery bypass graft patients whose ALOS did not substantially change over the same period. Two years after the project, ALOS for THA patients remained at ten days or below. This reduction in LOS and in the use of other hospital services translated into a mean total hospital charge decrease of $2045 per THA patient.

All primary condylar total knee replacement arthroplasties (TKAs) performed from 1977 to 1984 at the authors' institution were divided into two groups based on the use of continuous passive motion (CPM) in the immediate postoperative period. The control group consisted of 73 patients who were treated with 95 TKAs without postoperative CPM. The average age was 65.4 years. The study group consisted of 38 patients who had 51 TKAs in which CPM was used postoperatively. The mean patient age was 62.8 years. The most common diagnoses in both groups were osteoarthritis and rheumatoid arthritis. Range of motion (ROM) was recorded preoperatively, at discharge, at three months, one year, two years, and at the last follow-up visit. There were no statistically significant differences in the ROM between the two groups at any of these time periods. At two years, the mean flexion and extension in the study group were 99 degrees and -4 degrees, respectively, compared to 103 degrees and -5 degrees in the control group. The average hospital stay was 11.2 days in the study group, whereas it was 15.1 days in control group. In the control group, there was one superficial infection, no deep infections, and four pulmonary emboli compared with three superficial infections, two deep infections, and no pulmonary emboli in the study group. There was no difference in the transfusion requirements between the two groups. CPM is advocated by the authors to help achieve discharge ROM earlier, but the protocol has been changed to begin CPM on the second postoperative day to allow the wound to stabilize.

UNLABELLED Using a standardized strain of Escherichia coli 06 and a rabbit knee-joint model, we determined the following values: (1) the effective concentrations of amikacin and carbenicillin in vitro against Escherichia coli 06 when used singly or in combination; (2) the levels of each of these antibiotics in serum and synovial fluid after an intramuscular injection; (3) the effectiveness of amikacin in preventing intra-articular infection when it is administered thirty minutes before and six hours after an intra-articular inoculation of the same strain of Escherichia coli; and (4) the synergistic effects of amikacin and carbenicillin in combination both in vitro and in vivo when used together as a single dose six hours after intra-articular bacterial inoculation. Amikacin was much more effective when administered before joint inoculation and the minimum effective (inhibitory) concentrations of amikacin in vitro and in vivo were approximately the same. A synergistic effect of amikacin and carbenicillin in combination was more clearly evident in vitro than in vivo. CLINICAL RELEVANCE In vitro tests such as determinations of the minimum inhibitory concentration and the minimum bactericidal concentration, and the serum bactericidal test, can provide valuable guides for the determination of minimum goals for antibiotic therapy. These in vitro tests were related to concentrations of antibiotics in tissue assessed by in vivo bacterial challenge tests and were found to be predictive of efficacy in vivo.

A single intravenous dose of one gram of cefazolin was administered prophylactically to forty-eight patients undergoing total joint replacement. The serum half-life of the antibiotic was 1.8 hours, the same value found in normal volunteers. The mean concentration in bone during surgery was 5.7 micrograms per gram of bone. The mean concentration in synovial fluid during surgery was 24.4 micrograms per milliliter of fluid.

Concentrations of cephalothin or cefamandole were measured in serum, bone, synovial fluid, and wound drainage fluid in fifty-seven patients undergoing total hip or knee replacement after a two-gram intravenous bolus injection. The concentrations were similar in serum and synovial fluid for both antibiotics; however, in bone and drainage fluid the concentration of cefamandole was higher by a factor of three. Concentrations of the same antibiotic at the hip and knee were not significantly different even though a tourniquet was used for the knee replacement procedures. Clinical Relevance: The antibiotics penetrate bone and enter synovial fluid so rapidly that it is unnecessary to administer prophylactic antibiotics prior to the time of surgery.

In joints with bacterial arthritis, continuing prolonged destruction of cartilage may occur in spite of prompt, effective antibiotic therapy. We measured the extent to which early antibiotic therapy with ceforanide altered the degradation of the cartilage after arthritis due to Staphylococcus aureus had been produced in the knee joint in rabbits. Degradation of the cartilage was quantified by analyses for glycosaminoglycan and collagen. Three weeks after the infection was produced, the cartilage had lost more than half of its glycosaminoglycan whether the antibiotic therapy had been started at one, two, or seven days after infection. Beginning the antibiotic treatment one day after infection reduced over-all loss of collagen by 37 per cent and decreased the area of erosion of the infected articular surfaces. When antibiotic treatment was begun at four, eight, or twelve hours after infection, the loss of glycosaminoglycan averaged 18 per cent. Prophylaxis with antibiotics completely prevented any degradation of the cartilage. Clinical relevance: The findings reported here show how rapidly cartilage loses glycosaminoglycan when it is involved by arthritis caused by staphylococci and how early treatment of the infection reduces the loss of collagen. There is less protection against loss of glycosaminoglycan. The results emphasize the need for early diagnosis and treatment of infectious synovitis and support the rationale for early administration of antibiotics without waiting for identification of the responsible bacteria.

A patient-administered arthritis record system has been in use for 4 years. Thirty patients with various chronic arthritic conditions were studied to compare patient responses on the questionnaire to those obtained at the physician interview. Comparisons were also made between the "review of symptoms" and the actual physical findings documented in the medical record. The self-administered inventory of functional activities is a reliable and useful way to document specific activity achieved by a patient. Further, the questionnaires also aid in the evaluation of any therapeutic intervention and give a patient-perceived measurement of the clinical outcome in terms of quality of life. As a patient self-administered record, it allows for a major saving of physician time while acquiring accurate, complicated, but important, repetitive, time-oriented information. This system includes the American Rheumatism Association's Uniform Data Base for Rheumatic Diseases. An important set of questions has been added which improves functional assessment that is necessary to evaluate the success of surgical therapy.

In Reply.— In our article the single sentence in question should read "B27 testing is 95% sensitive and 94% specific," as pointed out by Dr Crawford. The change does not alter the discussion or conclusion of the article,which is that the neglected clinical history, appropriately used, is the preferable initial screening procedure for ankylosing spondylitis since it is easy, inexpensive, and universally available. We consider that the use of "predictive value" as suggested by Dr Crawford is unhelpful and confusing.

A single intravenous 2 g dose of cefoxitin, a broad spectrum antibiotic, was administered prophylactically just prior to operation on 60 patients undergoing total joint replacement (30 total hip replacements, 30 total knee replacements). Specimens of blood, bone, and synovial fluid were obtained during the operative procedure and assayed for cefoxitin concentration. Peak serum levels drawn five minutes after completion of antibiotic administration showed an average of 191 mcg/ml. Synovial fluid specimens were obtained an average of 33 minutes following antibiotic administration with a mean cefoxitin concentration of 72 mcg/ml. Bone samples from either the femoral condyle or femur head were taken an average of 65 minutes after the antibiotic was given and showed a mean cefoxitin concentration of 12 mcg/g. Simultaneous serum concentration was 63 mcg/ml. No allergic reactions occurred despite a history of skin rash after penicillin in eight patients. One patient developed deep infection caused by poor healing of the skin over the surgical site, thus leading to infection and involvement of the joint well after prophylaxis ended.

Forty-nine patients with 66 GUEPAR offset knee hinge replacements followed for one to 5 1/2 years were evaluated using the American Rheumatism Association Medical Information System (ARAMIS). The series included 37 female and 12 male patients whose average age was 69 years. Postoperative pain in 92% of patients decreased by an average of three grades. Maximum walking ability improved in 43% and worsened in 14%. Fewer walking aids were used by 51% of patients, whereas 18% needed increased support. Stair-climbing ability improved in 42% and worsened in 10%. Thirty-six additional functions were evaluated. Standing, housework and shopping abilities improved significantly. Range of motion improved from 87 degrees to 103 degrees and flexion contractures decreased by 11%. Varus and valgus abnormalities were almost uniformly corrected. Complications included a 23% rate of patella dislocation or subluxation. Extensor lag occurred in 26% of patients postoperatively, averaging 11 degrees. Deep infection occurred in six knees (9.1%); five were successfully treated for infection and the sixth was successfully treated by arthrodesis. Silastic bumpers broke in all cases and were associated in some instances with significant pain and effusion. Probable loosening has occurred in only one component.

Metal backing of glenoid components for total shoulder replacements and the use of bony ingrowth surfaces on these components have recently been introduced. In this study, finite element analyses were performed to determine the stress fields in the natural glenoid and to calculate the change in bone stresses after implantation of glenoid components of various designs. The effects of metal backing, keel geometry, and superior constraint on bone stresses indicate that stress distributions on the natural glenoid corresponded to bone morphology. Metal-backing the glenoid component may cause slight improvement in stress transfer to cortical bone. Altered fin geometry better stabilized the glenoid component. Superior restraints on the component intending to prevent subluxation increase stresses and may cause earlier loosening than encountered with unconstrained components.

A controlled study of 138 subjects demonstrated that the clinical history may be sensitive (95%) and specific (85%) in the differential diagnosis of ankylosing spondylitis when reliance on five specific historic features is made. Back pain that is insidious in onset, in a patient younger than 40 years, persisting for at least three months, associated with morning stiffness and improving with exercise is characteristic of inflammatory spinal disease. (JAMA237:2613-2614, 1977)

The clinical and roentgenologic data from 31 excised components from 19 revision arthroplasty cases were correlated with the histology and biochemistry of the membrane at the bone-cement or bone-prosthesis interface. Twenty-seven components were cemented and four were uncemented. Twenty-four implants were clinically and roentgenologically loose, one was possibly loose, and six were well fixed. Loose components, whether cemented or not, demonstrated statistically higher prostaglandin E2 levels in the surrounding membrane compared to the nonloose group. Collagenase and M-collagenase levels were absent or insignificantly low in all specimens; no detectable interleukin 1 beta was found. This suggests that prostaglandin E2 may be associated with the bone lysis associated with prosthesis loosening.

This study investigates risk factors associated with mechanical loosening of cemented total hip arthroplasties. Mechanical failure was evaluated using survivorship analysis on all arthroplasties performed at the authors' institution by the Orthopedic Service from March 1971 until September 1983. Failure was defined as the necessity for replacement of one or more components for any reason other than infection. The failure rate was approximately 1.7% per year and, at 12 years, 20% of the hips had failed. Variables evaluated as potential risk factors for arthroplasty revision included weight, gender, age, surgeon, preoperative functional status, prosthetic type, and diagnosis. A Cox proportional hazard analysis indicated that weight (p less than 0.015) and age (p = 0.087) are important determinants of hip failure. The use of regression trees identified subsets of patients at differing risks for failure. Patients who weighed less than 75.22 kg had the best outcome with a 90% survival to 12 years. Patients weighing more than 75.22 kg are at varying risk depending on their age. These data define a subset of special-risk patients not previously described. Patients weighing more than 75.22 kg who were older than 75.4 years had a revision rate of 73% by eight years.

Ten cardiac transplant patients have had bilateral total hip or knee surgery for treatment of osteonecrosis secondary to corticosteroid immunosuppression. Nine had bilateral total hip arthroplasty and one had bilateral total knee arthroplasty for osteonecrosis of the tibial plateaus. The only immediate postoperative complication was in a single hip patient who had a nonfatal pulmonary embolism. Two patients died from cardiovascular causes; the remaining eight had excellent results from arthroplasty, with an average Harris hip rating of 95 at a mean follow-up period of 34 months. No patient had required revision surgery and radiographic follow-up examination has revealed no evidence of loosening of any of these cemented arthroplasties. One patient developed a late hematogeneous sepsis of one hip seven years after replacement from atypical mycobacterium three months following renal transplantation, which was done 11 years after cardiac transplantation. Total joint arthroplasty has resulted in excellent clinical and radiologic results in this patient population. Despite the increased risks of major surgery in these immunocompromised transplant recipients, total joint arthroplasty appears to be a safe and effective method of treatment of osteonecrosis of the hip.

Seventeen nonconstrained total elbow replacements were inserted in 12 patients. One patient died prior to the one-year follow-up examination, and two others required revision in the immediate postoperative period. The remaining 14 primary total elbow arthroplasties in 11 patients were included in this study. There were eight women and three men with an average age of 58.1 years. The diagnosis was rheumatoid arthritis in 12 patients and posttraumatic arthritis and juvenile rheumatoid arthritis each in one patient. Postoperatively, patients were immobilized in a long arm cast. The mean hospital stay was 4.3 days. At four weeks, the patients were seen for cast removal. Instructions were given for range of motion (ROM) exercises and patients were encouraged to resume normal daily activities as tolerated. No formal physical therapy was prescribed. The average follow-up period was 32 months. Preoperatively, the mean elbow motions were flexion 124 degrees, extension 34 degrees, pronation 65 degrees, and supination 44 degrees. At the last follow-up examination, ROM had improved significantly in all directions except extension (flexion 141 degrees, extension 36 degrees, pronation 77 degrees, and supination 61 degrees). There was one ulnar nerve palsy that only partially resolved. Another patient's elbow had initially subluxed due to excessive shortening of the humerus; however, he had an excellent ROM and was asymptomatic at 31 months. There were no dislocations or wound healing problems. Cast immobilization provides an effective means of promoting soft-tissue healing, permitting early discharge from the hospital and simplifying the postoperative rehabilitation while achieving satisfactory ROM without formal physical therapy.

A new theory is introduced to describe some of the influences of mechanical stresses on chondroosseous biology. It is proposed that degeneration and ossification is a normal process for all cartilage in the appendicular skeleton, which is accelerated by intermittently applied shear stresses (or strain energy), and inhibited or prevented by intermittently applied hydrostatic pressure. These concepts were applied using finite element computer models in an effort to predict the ossification pattern of the prenatal and postnatal femoral anlage. The theoretical calculations successfully predicted the key features of skeletal morphogenesis including the development of the primary ossification site, a tubular diaphysis and marrow cavity, metaphyseal and epiphyseal trabecular bone, the location and geometry of the growth plate, the appearance and location of the secondary ossific nucleus, and the existence and thickness distribution of articular cartilage. The results suggest that degenerative joint disease in immobilized or nonload-bearing mature joints may be a manifestation of the final stage in the ossification of the anlage. In nonfunctional joints, the absence or reduction of intermittent hydrostatic pressure in the articular cartilage permits cartilage degeneration and the progressive advance of the ossification front toward the joint surface until the articular cartilage has been ossified.

Five pelvises were photographed, roentgenographed, and sequentially sectioned or reamed to determine the location and appearance of the acetabular teardrop figure. The teardrop is located inferomedially in the acetabulum, just superior to the obturator foramen. The lateral lip is the exterior, and the medial lip is the interior of the acetabular wall. The ilioischial line projects over the medial acetabulum only fortuitously on the straight anteroposterior (AP) roentgenogram. Because of parallax, the relationship between the ilioischial line and the teardrop changes for views varying as little as 10 degrees in horizontal obliquity from the true AP roentgenogram. Because the teardrop comprises a well-defined, constant portion of the medial acetabular wall whereas the ilioischial line does not, the authors recommend using the acetabular teardrop rather than the ilioischial line for the detection and measurement of medial and superior acetabular migration.

This is a report of a 46-year-old male who developed an Allescheria boydii infection secondary to excision of an interdigital neuroma. Previously reported cases of infection occurred in an immunosuppressed patient and in patients on systemic corticosteroid therapy, but not associated with a surgical wound. This patient received multiple local corticosteroid injections which may have produced local as well as systemic immunosuppression. Fungal cultures were not taken for many months and thus the true etiology of the infection was not discovered until late. The importance of obtaining fungal cultures particularly in patients receiving corticosteroid therapy, either local infiltration or systemic, cannot be overemphasized.

Sixty patients with bone and joint infections secondary to gram negative infection were evaluated in relation to treatment with amikacin. Forty-seven of these patients had osteomyelitis, and 13 had joint infections, including 3 prosthetic replacements. The patients' average was 35 years and there was no predilection for any particular skeletal location. Only 6 patients had no associated predisposing medical problems. Of these problems fracture, diabetes and narcotic abuse were most common. Thirty patients had Psuedomonas infection, and 15 others had multiple pathogens including Pseudomonas. Aminoglycoside antibiotics had been previously used in 25. Amikacin was given for an average of 22 days with a mean dose of 13.4 mg/kg. Bone and synovial fluid levels of amikacin were in therapeutic range. At least 48 patients had concurrent local wound treatment in addition to parenteral administration of amikacin. In 47 patients enough information was available to determine the efficacy of treatment. Twenty-seven (57%) of these patients were considered cured, both clinically and for bacteriologic response; and additional 9 (19%) were considered partially cured. Amikacin is effective against susceptible pathogens in bone and joint infections and is a reasonable choice when aminoglycoside antibiotic is indicated.

A recent survey of congenital hand anomalies has revealed that symphalangism of the distal interphalangeal joint is more frequent than had previously been reported. To date, however, only 3 familial pedigrees have been documented in the literature. The family reported in this article had 9 individuals spanning 4 generations affected with symphalangism of the distal interphalangeal joint. In all cases, this was associated with ankylosis of the distal interphalangeal joint of the second through fifth toes. One child in the family also had brachyphalangism bilaterally as well as a bifid distal phalanx of the thumb. The world's literature does not seem to include a similar case. As with previous cases of fusion of the distal interphalangeal joint, there was little functional disability resulting from this anomaly and we do not recommend operative procedures to restore motion.

In a prospective study of 14 consecutive infected total knee arthroplasties ( TKAs ) treated through 1979, the management consisted of: (1) 11 delayed exchange arthroplasties, with 2 failures requiring above-knee amputation; (2) 2 in situ debridements; and (3) 1 arthrodesis. The final outcome of the delayed exchange arthroplasty group regarding joint pain, patient function, and joint performance was (a) inferior to that of primary TKA (before infection), (b) better than that of resection arthroplasty, and (c) worse than that of a control group of non-infected TKAs respectively. Debridement without prosthesis resection was successful only in cases of immediate postoperative infection (2 successes in 4 TKAs ) and uniformly unsuccessful in infections occurring beyond the perioperative period (4 failures in 4 TKAs ). The study indicates that delayed exchange total knee arthroplasty is a reasonable alternative to arthrodesis following resection of an infected TKA and can be performed without undue risk of recurrent infection.

All patients treated by total hip arthroplasty (THA) from 1971 to 1980 were analyzed to assess cause and rate of revision. Multiparameter radiographic analysis of failed femoral components ( FFC ) and matched control THAs was performed to determine predictability of failure, based on initial postarthroplasty and subsequent follow-up radiographic examinations. Rate of revision for all causes was 10.4% (35 THAs ) for 335 THAs in 270 patients with a follow-up period averaging 5.0 (range, 2-10) years. Cause of revision was component loosening in 7.2% (24 THAs ) [23 (6.9%) with femoral component loosening, 3 (0.9%) progressing to stem fracture, 3 (0.9%) with associated acetabular loosening, and 1 (0.3%) with isolated acetabular loosening]; infection in 1.5% (5 THAs ); and 1.8% (6 THAs ) comprised other causes. Older, inactive women, light in body weight (not including 42 THAs for rheumatoid arthritis), had fewer clinical failures. Second revision rate after revision for component loosening was 29% after an average follow-up period of 3.1 years. Paired comparison of initial postoperative and time-of-failure radiographs of 15 patients with THAs requiring revision for femoral component loosening versus initial postoperative and equivalent follow-up radiographs of 15 age-, sex-, weight-, activity-, diagnosis-, prosthesis-, and follow-up-matched patients with clinically successful THAs revealed the FFC group to be worse with regard to the following parameters: on initial postoperative radiographs, (a) femoral and acetabular bone-cement radiolucency (p less than 0.006 and p less than 0.02, respectively) and (b) when analyzed together, femoral bone-cement radiolucency, calcar-collar contact, femoral metal-cement radiolucency, femoral cement mantle adequacy, cement adequacy distal to the femoral component stem tip, and femoral component stem position (p less than 0.006); and on failure/equivalent radiographs, (a) femoral metal-cement radiolucency (p less than 0.01) and (b) when analyzed together, femoral metal-cement and bone-cement radiolucency, subsidence, cortical hypertrophy, calcar resorption, and sclerosis (p less than 0.006).