Matthew J. Kraay

Fixation, Polyethylene Wear, and Pelvic Osteolysis in Primary Total Hip Replacement

A multicenter retrospective review was performed analyzing 1081 primary total hip replacements in 944 patients using the Harris Galante-I cementless acetabular component with screw fixation. All patients were followed up for a minimum of 5 years with a mean followup of 81 months. Linear polyethylene wear averaged 0.11 mm/year (range, 0-0.86 mm/year). Pelvic osteolysis was seen in 25 patients (2.3%). Migration of the acetabular component was seen in four hips. A subgroup of patients was reanalyzed at a minimum followup of 10 years. The mean linear polyethylene wear rate remained 0.11 mm/year. In this group, only one socket had migrated. There was an association between wear rate and age. On average, younger patients had higher wear rates. The risk for having pelvic osteolysis develop and the need for revision surgery also was age-related. Twenty-two percent of hip replacements (15 hips) in patients younger than 50 years of age at the time of their index operation had pelvic osteolysis develop. In contrast, for patients older than 50 years of age at the time of surgery only 7.8% (eight hips) had osteolysis of the pelvis develop. For patients older than 70 years of age at the time of primary total hip replacement, none had pelvic osteolysis develop.

Do Ceramic Femoral Heads Reduce Taper Fretting Corrosion in Hip Arthroplasty? A Retrieval Study

BackgroundPrevious studies regarding modular head-neck taper corrosion were largely based on cobalt chrome (CoCr) alloy femoral heads. Less is known about head-neck taper corrosion with ceramic femoral heads.Questions/purposesWe asked (1) whether ceramic heads resulted in less taper corrosion than CoCr heads; (2) what device and patient factors influence taper fretting corrosion; and (3) whether the mechanism of taper fretting corrosion in ceramic heads differs from that in CoCr heads.MethodsOne hundred femoral head-stem pairs were analyzed for evidence of fretting and corrosion using a visual scoring technique based on the severity and extent of fretting and corrosion damage observed at the taper. A matched cohort design was used in which 50 ceramic head-stem pairs were matched with 50 CoCr head-stem pairs based on implantation time, lateral offset, stem design, and flexural rigidity.ResultsFretting and corrosion scores were lower for the stems in the ceramic head cohort (p = 0.03). Stem alloy (p = 0.004) and lower stem flexural rigidity (Spearman’s rho = −0.32, p = 0.02) predicted stem fretting and corrosion damage in the ceramic head cohort but not in the metal head cohort. The mechanism of mechanically assisted crevice corrosion was similar in both cohorts although in the case of ceramic femoral heads, only one of the two surfaces (the male metal taper) engaged in the oxide abrasion and repassivation process.ConclusionsThe results suggest that by using a ceramic femoral head, CoCr fretting and corrosion from the modular head-neck taper may be mitigated but not eliminated.Clinical RelevanceThe findings of this study support further study of the role of ceramic heads in potentially reducing femoral taper corrosion.

Patellar fracture type and prognosis in condylar total knee arthroplasty.

Fractures of the patella occurred following implantation of 36 condylar total knee arthroplasties in 35 patients. The end results were evaluated in relation to fracture type after an average 4.5-year follow-up period. The follow-up observations included a physical examination, quantitative knee score, and roentgenographic evaluations of extremity alignment and implant position. Twenty-two of the 36 knees had a good or excellent knee score and 14 had a fair or worse score at the time of the latest follow-up evaluation. The satisfactory knees had an average arc of motion of 100 degrees, while the unsatisfactory knees had an average arc of motion of 80 degrees. Fourteen fractures through the mid-body or superior pole of the patella not involving the implant, cement, or quadriceps mechanism (Type I) and two nondisplaced fractures through the inferior pole of the patella (Type IIIB) were managed nonoperatively, with all knees rating either a good or excellent score. Fractures of the patella disrupting the quadriceps mechanism or implant/bone/cement composite (Type II) were managed operatively in the six knees. Fractures of the inferior pole of the patella with disruption of the patellar ligament (Type IIIA) were managed operatively in seven of eight knees (one patient refused surgery). Lateral fracture-dislocations were managed operatively in all six knees. Six of the knees operated upon had a good or better score, and nine knees were rated as poor or failed. Those fractures alignment and implant position were seen had the more severe patellar fractures and poorest outcomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Primary semiconstrained total elbow arthroplasty. Survival analysis of 113 consecutive cases

We used survival analysis to evaluate 113 consecutive semiconstrained total elbow arthroplasties (TEAs) in 95 patients at a maximum follow-up of 99 months. Our criteria for failure were mechanical malfunction, revision for any reason, and deep infection. The primary diagnosis was inflammatory arthritis in 86 elbows, post-traumatic arthritis in 6, supracondylar nonunion or fracture in 12, osteoarthritis in 2 and other causes in 3. Seven failures were due to deep infection, and five of these had a primary diagnosis of inflammatory arthritis. Eight failures were revised or had revision recommended for aseptic loosening, and six of these were in patients with post-traumatic arthritis or supracondylar nonunion. The cumulative survival for TEAs performed for post-traumatic arthritis, fractures or supracondylar nonunion was 73% at three years and 53% at five years, significantly worse than the cumulative three- and five-year survivals of 92% and 90%, respectively, for patients with inflammatory arthritis. TEA with a semiconstrained prosthesis appears to have a satisfactory survival in selected patients with arthritic disorders. The incidence of deep infection was reduced by improvements in surgical technique and postoperative management, and the routine use of antibiotic-impregnated cement. The incidence of aseptic loosening was low, except in patients with supracondylar nonunion or post-traumatic arthritis.

Distal femoral replacement with allograft/prosthetic reconstruction for treatment of supracondylar fractures in patients with total knee arthroplasty.

Large-segment distal femoral allografts were used in conjunction with non-linked total knee prostheses to reconstruct bone deficits following supracondylar fracture of the femur in seven patients with previous total knee arthroplasties. Three patients with multiple medical problems died of unrelated causes prior to a minimum 2 year follow-up. Indications for surgery were previously failed attempts at osteosynthesis and significant fracture comminution, osteopenia, and intercondylar extension or femoral component loosening. Specifics of the surgical technique included subperiosteal excision of the involved distal femur with retention of a soft tissue sleeve containing the collateral ligaments and reconstruction with a large-segment allograft and a stemmed, semiconstrained total knee prosthesis. Cement fixation using pressurized technique with intramedullary plugging of the tibial and femoral canal was routinely used to secure the prosthesis/allograft construct to the host bone. Postoperative complications included one dislocation, which was successfully treated closed, and one popliteal artery injury, which was successfully repaired. There were no postoperative infections. Two patients, however, had some degree of persistent instability, warranting bracing at the time of last follow-up. Using the Knee Society rating system, the average knee score for these patients was 71, and the average pain score and function score were 33 and 49, respectively. Range of motion averaged 96 degrees. All of the femoral components were well fixed at last follow-up. Results of this study indicate that large-segment distal femoral allografts used in conjunction with nonlinked knee prostheses can be an acceptable method of treatment of these difficult reconstructive problems.

In vivo degradation of polyethylene liners after gamma sterilization in air.

BACKGROUND Ultra-high molecular weight polyethylene degrades during storage in air following gamma sterilization, but the extent of in vivo degradation remains unclear. The purpose of this study was to quantify the extent to which the mechanical properties and oxidation of conventional polyethylene acetabular liners treated with gamma sterilization in air change in vivo. METHODS Fourteen modular cementless acetabular liners were revised at an average of 10.3 years (range, 5.9 to 13.5 years) after implantation. All liners, which had been machined from GUR 415 resin, had been gamma-sterilized in air; the average shelf life was 0.3 year (range, 0.0 to 0.8 year). After removal, the components were expeditiously frozen to minimize ex vivo changes to the polyethylene prior to characterization. The average duration between freezing and testing was 0.6 year. Mechanical properties and oxidation were measured with use of the small-punch test and Fourier transform infrared spectroscopy, respectively, in the loaded and unloaded regions of the liners. RESULTS There was substantial regional variation in the mechanical properties and oxidation of the retrieved liners. The ultimate load was observed to vary by >90% near the surface. On the average, the rim and the unloaded bearing showed evidence of severe oxidation near the surface after long-term in vivo aging, but these trends were not typically observed on the loaded bearing surface or near the backside of the liners. CONCLUSIONS The mechanical properties of polyethylene that has been gamma-sterilized in air may decrease substantially in vivo, depending on the location in the liner. The most severe oxidation was observed at the rim, suggesting that the femoral head inhibits access of oxygen-containing body fluids to the bearing surface. This is perhaps why in vivo oxidation has not been associated with clinical performance to date.

Cementless two-staged total hip arthroplasty for deep periprosthetic infection.

Two-staged exchange with delayed reimplantation of a new prosthesis is considered by many to be the preferred method of treatment for deep periprosthetic infection after total hip arthroplasty. Until recently, most authors of previously published reports of this two-staged exchange procedure have used cemented implants fixed with antibiotic-containing bone cement. In view of the superior results of revision total hip arthroplasties with cementless implants, we reviewed the results of 33 two-staged revision total hip arthroplasties done for deep infection using cementless femoral components. There were no recurrent infections in the 28 patients in this study who had a 2-year minimum followup. Two patients developed a new infection with a different organism after reimplantation of their hip. Three patients with considerable acetabular bone deficiency had acetabular component revision for aseptic loosening; however, there were no cases of femoral component loosening. The overall infection rate of 7% using this approach was comparable to previous reports of two-staged revision total hip arthroplasties done with cemented components fixed with antibiotic-containing bone cement. In addition, cementless femoral component fixation seemed to be more reliable and durable in comparison to previous reports of revision total hip arthroplasty with cemented stems. The results of this study support the continued use of cementless implant fixation for two-staged reconstruction of the infected total hip arthroplasty. Level of Evidence: Therapeutic study, Level IV-1 (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Hydrostatic pressure induces apoptosis in human chondrocytes from osteoarthritic cartilage through up-regulation of tumor necrosis factor-α, inducible nitric oxide synthase, p53, c-myc, and bax-α, and suppression of bcl-2

Hydrostatic pressure (HP) is thought to increase within cartilage extracellular matrix as a consequence of fluid flow inhibition. The biosynthetic response of human articular chondrocytes to HP in vitro varies with the load magnitude, load frequency, as well as duration of loading. We found that continuous cyclic HP (5 MegaPascals (MPa) for 4 h; 1 Hz frequency) induced apoptosis in human chondrocytes derived from osteoarthritic cartilage in vitro as evidenced by reduced chondrocyte viability which was independent of initial cell densities ranging from 8.1 × 104 to 1.3 × 106 cells ml−1. HP resulted in internucleosomal DNA fragmentation, activation of caspase‐3, and cleavage of poly‐ADP‐ribose polymerase (PARP). At the molecular level, induction of apoptosis by HP was characterized by up‐regulation of p53, c‐myc, and bax‐α after 4 h with concomitant down‐regulation of bcl‐2 after 2 h at 5 MPa as measured by RT‐PCR. In contrast, β‐actin expression was unchanged. Real‐time quantitative RT‐PCR confirmed a HP‐induced (5 MPa) 1.3–2.6 log‐fold decrease in bcl‐2 mRNA copy number after 2 and 4 h, respectively, and a significant increase (1.9–2.5 log‐fold) in tumor necrosis factor‐α (TNF‐α) and inducible nitric oxide synthase (iNOS) mRNA copy number after 2 and 4 h, respectively. The up‐regulation of p53 and c‐myc, and the down‐regulation of bcl‐2 caused by HP were confirmed at the protein level by Western blotting. These results indicated that HP is a strong inducer of apoptosis in osteoarthritic human chondrocytes in vitro. J. Cell. Biochem. 87: 266–278, 2002.

Lipopolysaccharide found in aseptic loosening of patients with inflammatory arthritis

Aseptic loosening of orthopaedic implants occurs in the absence of clinical signs of infection. Nevertheless, bacterial endotoxins derived from subclinical infections, systemic sources, or the implant manufacturing process may contribute to aseptic loosening. Also, the rate of implant infection is greater in patients with inflammatory arthritis than in patients with osteoarthritis. We hypothesized that lipopolysaccharide, the classic endotoxin derived from gram-negative bacteria, is more prevalent in periprosthetic tissue surrounding aseptically loose implants in patients with inflammatory arthritis than in patients with osteoarthritis. To test this, we used a modified Limulus amebocyte assay not affected by β-glucan-like molecules in mammalian tissues. Lipopolysaccharide rarely was detected in periprosthetic tissue from patients with osteoarthritis and aseptic loosening (one of six patients). In contrast, lipopolysaccharide was detected despite the absence of any clinical signs of infection in peri-prosthetic tissue from all four patients with inflammatory arthritis (rheumatoid arthritis, juvenile rheumatoid arthritis, and systemic lupus erythematosus). Lipopolysaccharide also was detected in two patients with gram-negative infections, who were included as positive control subjects. Endotoxins derived from low-grade or systemic bacteremia may be important contributors to aseptic loosening particularly in patients with autoimmune conditions such as inflammatory arthritis.

Effect of resin type and manufacturing method on wear of polyethylene tibial components.

The purpose of this study was to examine the effect of ultrahigh molecular weight polyethylene resin type and manufacturing method on wear of Miller-Galante I and II tibial knee components. Thirteen Miller-Galante I and 10 Miller-Galante II components were retrieved at revision surgery. The Miller-Galante I tibial components were made by direct compression molding of Hi-fax 1900 resin and the Miller-Galante II tibial components were made by machining from ram extruded rod of GUR 415 resin. Both generations were gamma radiation sterilized in air. The Miller-Galante I retrievals had significantly more wear damage in the form of scratching and embedded metallic debris, whereas the Miller-Galante II retrievals had significantly more wear damage in the form of delamination. For the implants with an implantation time of 5 years or more, the Miller-Galante II polyethylene had a significantly greater maximum density value than did the Miller-Galante I polyethylene. Examination of thin sections of the Miller-Galante II components revealed that delamination occurred through a subsurface region of severely oxidatively degraded polyethylene; no such subsurface degraded region was observed for the Miller-Galante I components. The results of this study suggest that delamination of polyethylene tibial components that have been gamma radiation sterilized (in air) is influenced by resin type or manufacturing method or both.