Steven A. Stuchin

Superinduction of cyclooxygenase-2 activity in human osteoarthritis-affected cartilage. Influence of nitric oxide.

Cartilage specimens from osteoarthritis (OA)-affected patients spontaneously released PGE2 at 48 h in ex vivo culture at levels at least 50-fold higher than in normal cartilage and 18-fold higher than in normal cartilage + cytokines + endotoxin. The superinduction of PGE2 production coincides with the upregulation of cyclooxygenase-2 (COX-2) in OA-affected cartilage. Production of both nitric oxide (NO) and PGE2 by OA cartilage explants is regulated at the level of transcription and translation. Dexamethasone inhibited only the spontaneously released PGE2 production, and not NO, in OA-affected cartilage. The NO synthase inhibitor HN(G)-monomethyl-L-arginine monoacetate inhibited OA cartilage NO production by > 90%, but augmented significantly (twofold) the spontaneous production of PGE2 in the same explants. Similarly, addition of exogenous NO donors to OA cartilage significantly inhibited PGE2 production. Cytokine + endotoxin stimulation of OA explants increased PGE2 production above the spontaneous release. Addition of L-NMMA further augmented cytokine-induced PGE2 production by at least fourfold. Inhibition of PGE2 by COX-2 inhibitors (dexamethasone or indomethacin) or addition of exogenous PGE2 did not significantly affect the spontaneous NO production. These data indicate that human OA-affected cartilage in ex vivo conditions shows (a) superinduction of PGE2 due to upregulation of COX-2, and (b) spontaneous release of NO that acts as an autacoid to attenuate the production of the COX-2 products such as PGE2. These studies, together with others, also suggest that PGE2 may be differentially regulated in normal and OA-affected chondrocytes.

Effect of rotation and knee flexion on radiographic alignment in total knee arthroplasties.

A synthetic femur and tibia were used to create a model resurfacing total knee arthroplasty. The femoral component was placed in 7 ° valgus; the tibial component was placed in 2 ° varus with a 5 ° posterior slope. The overall anatomic alignment was 5 ° valgus. A series of radiographs were taken on 14 inch × 17 inch plates, in full extension and 10 ° flexion, with the limb rotated, in 5 ° increments, from 20 ° external rotation to 25 ° internal rotation. Seven orthopaedic surgeons independently measured the tibiofemoral angle and tibial alignment for each series of radiographs; interobserver variability was insignificant. Average radiographic anatomic alignment ranged from 2.29 ° valgus in 20 ° external rotation and 10 ° flexion, to 6.73 ° valgus in 25 ° internal rotation and 10 ° flexion. Limb rotation and knee flexion of 10 °, either alone or in combination, had a highly statistically significant effect on measured values of the anatomic alignment. Tibial alignment ranged from 5 ° varus in 20 ° external rotation to 3 ° valgus in 25 ° internal rotation, with the knee flexed 10 °. The variability associated with changes in rotation was statistically significant. Changes associated with rotation, when the knee was flexed 10 °, were not significantly different than those measured with the knee fully extended. Even in a well aligned total knee arthroplasty, limb positioning at the time of radiographic assessment will alter the apparent alignment indices, making objective evaluation difficult.

The management of vascular injuries associated with total hip arthroplasty

Approximately 100,000 total hip reconstructions are done annually in the United States. The nature of the surgical technique in a field close to the iliac and femoral vessels makes the occurrence of vascular injury an occasional but serious complications. We have reviewed retrospectively our experience of five cases of vascular injuries with total hip replacement and an additional 63 cases in the literature to identify those patients at risk and to define the management of these injuries. For the entire group of 68 patients, most injuries were sustained on the left side (66%), and 39% were seen in revisions. Complications were related to cement incorporation of the iliac vessels (44%), aggressive medial retraction (17%), excessive traction on atherosclerotic vessels (10%), and improper technique in preparation of the acetabulum. The most commonly injured vessels were the external iliac artery (36), common femoral artery (17), and external iliac vein (6). Twenty-seven of these injuries required emergent surgery, most for hemorrhage (66%). Injuries consisted of thromboembolic complications leading to distal ischemia (46%), vessel lacerations (26%), pseudoaneurysms (25%), and arteriovenous fistulas (3%). Vascular repair was individualized and included suture repair, thrombectomy and patch angioplasty, embolectomy, and arterial and venous bypass procedures. There was an overall 7% mortality and a 15% incidence of limb loss. Risk factors include (1) revision procedures, (2) left-sided procedures, and (3) intrapelvic migration of the acetabular component of the hip prosthesis. Elective vascular workup and preliminary retroperitoneal exposure of the iliac vessels at time of hip arthroplasty is recommended for patients at risk.

Subtrochanteric femoral shortening osteotomy in total hip arthroplasty for high-riding developmental dislocation of the hip

A surgical technique, which uses a transverse osteotomy, for subtrochanteric femoral shortening and derotation in total hip arthroplasty for high-riding developmental dislocation of the hip is described. Anteversion is set by rotating the osteotomy fragments, and torsional stability is augmented with allograft struts and cables when indicated. Eight patients with 9 total hip arthroplasties were followed for an average of 43 months (range, 24-84 months). Good to excellent results were obtained in 87% of patients (7 of 8). Eight of 9 osteotomies (89%) demonstrated radiographic evidence of healing at an average of 5 months. One patient had an asymptomatic nonunion of the osteotomy site but still had a good overall clinical result. Another patient suffered fatigue failure of a distally ingrown porous device, which necessitated revision total hip arthroplasty 18 months after surgery. Subtrochanteric osteotomy in total hip arthroplasty for developmental dislocation of the hip allows for acetabular exposure and diaphyseal shortening while facilitating femoral derotation. Furthermore, proximal femoral bone stock is maintained and some of the potential complications of greater trochanteric osteotomy may be avoided.

Osteopontin : An intrinsic inhibitor of inflammation in cartilage

OBJECTIVE To identify extracellular and intraarticular matrix components that are differentially expressed in normal and osteoarthritis (OA)-affected cartilage and to investigate their functions with respect to regulation of mediators of inflammation. METHODS Differential-display reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of a pool of messenger RNA (mRNA) from 10 human OA cartilage samples and 5 normal cartilage samples was performed using arbitrary primers. Confirmatory analysis of the up-regulated transcripts of fibronectin (FN) and osteopontin (OPN) was performed by RT-PCR of individual RNA samples from a separate set of donors. The effect of recombinant OPN (or anti-OPN antiserum) on chondrocyte function was examined by analyzing the spontaneous or interleukin-1 (IL-1)-induced release of nitric oxide (NO) and prostaglandin E2 (PGE2) from human OA-affected cartilage under ex vivo conditions. RESULTS Up-regulation (300-700%) of FN and OPN mRNA was observed in human OA-affected cartilage as compared with normal cartilage. Functional analysis of the role of OPN in OA cartilage showed that 1) Addition of 1 microg/ml (20 nM) of recombinant OPN to human OA-affected cartilage under ex vivo conditions inhibited spontaneous and IL-1beta-induced NO and PGE2 production, and 2) neutralization of intraarticular OPN with anti-OPN antiserum augmented NO production. CONCLUSION The data indicate that one of the functions of intraarticular OPN, which is overexpressed in OA cartilage, is to act as an innate inhibitor of IL-1, NO, and PGE2 production. These findings suggest that the production of pleiotropic mediators of inflammation that influence cartilage homeostasis, such as NO and PGE2, is regulated by the interaction of chondrocytes with differentially expressed proteins within the extracellular matrix.

Wear rates of ceramic-on-ceramic bearing surfaces in total hip implants: A 12-year follow-up study

A retrospective clinical and radiographic analysis was performed on 58 patients (60 hips; mean age at time of surgery, 45.2 years) at a minimum of 10-year follow-up (mean, 12.7 years) after total hip replacement using a ceramic-on-ceramic hearing total hip implant (Autophor, Smith and Nephew, Memphis, TN). Mean wear rate at final follow-up was 0.21 mim, averaging 0.016 mm/y. There were no cases of periprosthetic osteolysis in the acetabuulum or femur. For the unrevised components, there were 3 (5%) cases of protrusio acetabuli and 4 (7%) cases of acetabular component loosening. On the femoral side, 78.3% had distal pedestal formation, and 83% had greater than 2 mm implant-bone radiolucencies in more than 5 Gruen zones as a result of gross motion of the stem. Despite radiographic evidence of implant loosening, this hard bearing articulation functioned well in vivo for more than 12 years with remarkably low wear--approximately one tenth the rate reported for metal-on-polyethylene total hip bearings.

Catastrophic failure of the acetabular component in a ceramic-polyethylene bearing total hip arthroplasty

Recent research in total hip arthroplasty has focused on attempts to decrease wear at the femoral head-acetabulum articulation, to limit the production of debris that is believed to lead to osteolysis and prosthetic loosening. The use of ceramic-on-polyethylene bearing surfaces has been reported to produce lower wear rates and therefore may increase the life expectancy of the joint arthroplasty. Problems with this bearing have been reported to be due to ceramic femoral head fracture. Reported here are 2 cases of catastrophic failure of total hip arthroplasties, involving a ceramic femoral head, caused by failure of the polyethylene acetabular liner, with subsequent penetration of the femoral head through the acetabular shell.

Results of cemented metal-backed acetabular components

Abstract The clinical and radiographic results of 86 primary total hip arthroplasties performed in 74 patients from 1983 to 1987 with a cemented metal-backed acetabular component and a cemented collared straight femoral stem with a 32-mm head were reviewed at a mean follow-up of 10.1 years. Seven patients (9.2%) underwent acetabular component revision at a mean of 9.0 years after implantation; an additional 24 components (31.6%) demonstrated evidence of radiographic loosening, resulting in a total failure rate of 40.8%. Periacetabular radiolucencies were noted in Charnley zones at the following rates: 34.2% in zone I, 18.4% in zone II, and 27.6% in zone III. In addition, 18.4% and 38.2% of implants demonstrated evidence of migration and excessive polyethylene wear. Excessively vertical cup placement (>49° inclination) at the time of initial arthroplasty was statistically correlated with polyethylene wear, implant migration, and fixation failure. A trend of increasing implant failure was also noted with decreasing polyethylene liner thickness. Periacetabular cement mantle thickness was not statistically correlated with subsequent component loosening or failure. Results of Kaplan-Meier survivorship analysis using revision as an endpoint showed 93.6% survivorship at 10 years and 88.4% at 12 years. The mean modified Harris hip scores were 46.9 preoperatively and 81.8 at final follow-up. The significant overall rates of radiographic loosening, migration, polyethylene wear, and implant revision confirm the suspected trend of increasing failure rates of cemented metal-backed acetabular components over time.

Analysis of removed autophor ceramic-on-ceramic components

Six Autophor alumina ceramic total hip arthroplasty components (5 removed for stem loosening and 1 for cup loosening) were evaluated to determine the nature and extent of wear by direct measurement, scanning electron microscopy of wear debris, and histology. Component implantation averaged 29 months (range, 8-54 months). All components had evidence of marked wear, including gross loss of material, which increased with the duration of implantation.

Thrombotic and bleeding complications after orthopedic surgery.

BACKGROUND Thrombotic and bleeding complications are major concerns during orthopedic surgery. Given the frequency of orthopedic surgical procedures and the limited data in the literature, we sought to investigate the incidence and risk factors for thrombotic (myocardial necrosis and infarction) and bleeding events in patients undergoing orthopedic surgery. METHODS AND RESULTS We performed a retrospective cohort analysis of 3,082 consecutive subjects ≥21 years of age undergoing hip, knee, or spine surgery between November 1, 2008, and December 31, 2009. Patient characteristics were ascertained using International Classification of Diseases, Ninth Revision, diagnosis coding and retrospective review of medical records, and laboratory/blood bank databases. In-hospital outcomes included myocardial necrosis (elevated troponin), major bleeding, coded myocardial infarction, and coded hemorrhage as defined by International Classification of Diseases, Ninth Revision, coding. Of the 3,082 subjects, mean age was 60.8 ± 13.3 years, and 59% were female. Myocardial necrosis, coded myocardial infarction, major bleeding, and coded hemorrhage occurred in 179 (5.8%), 20 (0.7%), 165 (5.4%), and 26 (0.8%) subjects, respectively. Increasing age (P < .001), coronary artery disease (P < .001), cancer (P = .004), and chronic kidney disease (P = .01) were independent predictors of myocardial necrosis, whereas procedure type (P < .001), cancer (P < .001), female sex (P < .001), coronary artery disease (P < .001), and chronic obstructive pulmonary disease (P = .01) were independent predictors of major bleeding. CONCLUSION There is a delicate balance between thrombotic and bleeding events in the perioperative period after orthopedic surgery. Perioperative risk of both thrombosis and bleeding deserves careful attention in preoperative evaluation, and future prospective studies aimed at attenuating this risk are warranted.