Showing papers in "Journal of Arthroplasty in 1994"

Acetabular defect classification and surgical reconstruction in revision arthroplasty. A 6-year follow-up evaluation.

Abstract: From 1982 to 1988, 147 cemented acetabular components were revised with cementless hemispherical press-fit components, with an average follow-up period of 5.7 years (range, 3–9 years). Acetabular defects were typed from 1 to 3 and reconstructed with a bulk or support allograft. Type 1 defects had bone lysis around cement anchor sites and required particulate graft. Type 2A and B defects displayed progressive bone loss superiorly and required particulate graft, femoral head bulk graft, or cup superiorization. Type 2C defects required medial wall repair with wafer femoral head graft. Type 3A and B defects demonstrated progressive amounts of superior rim deficiencies and were treated with structural distal femur or proximal tibia allograft. Six of the 147 components (4.0%), all type 3B, were considered radiographically and clinically unstable, warranting revision. Three of the six were revised. Moderate lateral allograft resorption was noted on radiographs, but host-graft union was confirmed at rerevision. Size, orientation, and method of fixation of the allografts play an important role in the integrity of structural allografts, while adequate remaining host-bone must be present to ensure bone ingrowth.

Revision total knee arthroplasty. Comparison of outcome following primary proximal tibial osteotomy or unicompartmental arthroplasty.

Abstract: Forty-three patients who had undergone revision total knee arthroplasty following either primary, medial unicondylar arthroplasty (23 patients) or valgus tibial osteotomy (20 patients) for medial compartment osteoarthritis were reviewed. Although the two groups had similar knee scores and range of motion at review, six patients (30%) who had undergone prior tibial osteotomy suffered serious postoperative complications. Of these, four patients had a deep infection. It was felt that several factors were responsible, resulting largely from difficulties in gaining access to the lateral tibial plateau and subsequently causing impairment of wound vascularity and healing. In contrast, those patients undergoing revision of unicondylar prostheses did not experience wound healing problems, but it was noted that in half of the cases, there was significant bone loss from the medial tibial plateau.

Comparison of hip force calculations and measurements in the same patient

Abstract: Many investigations report hip-contact-force estimates based either on mathematical models or on the output of instrumented implants. Data from instrumented implants have been consistently lower than mathematical predictions. The authors compared mathematical estimates derived from gait laboratory observations made in a patient with an instrumented hip implant. Appropriate modifications to past models resulted in force predictions that were reasonably similar to the output of the instrumented implant. Peak resultant forces were in the range of 2.5-3.5 body weight during level walking at a freely selected speed, while peak out-of-plane forces ranged from 0.6 to 0.9 body weight. Previous parametric hip-force predictions resulting from mathematically modeled surgical alterations may be high insofar as absolute peak values, but trends are likely correct.

Long-term results of cemented total hip arthroplasty in patients 45 years old or younger. A 16-year follow-up study.

Abstract: Forty-nine cemented total hip arthroplasties in patients younger than 45 years were reviewed, with an average follow-up period of 16.2 years. The results were compared with the same group previously reported at average follow-up periods of 4.5 and 9.2 years. Clinically satisfactory results were 27% at 16.2 years compared with 78% at 4.5 years and 58% at 9.2 years. The revision rate increased from 12% at 4.5 years to 33% at 9.2 years to 67% in this study. The revision rate for patients younger than 30 at the time of the index arthroplasty was 82% compared with 56% for those over 30. Impending failure was present in 81% of the 16 unrevised hips compared with 56% at 9.2 years and 29% at 4.5 years. Patients younger than 30, in Charnley category A or B, and with a diagnosis of osteonecrosis or osteoarthritis had the poorest clinical results. As in the previous two studies, the best results were obtained in category C patients who were over 30 years of age with inflammatory collagen disease. The purpose of this study is to report the long-term (average, 16.2 years) follow-up results of patients under the age of 45 who underwent cemented total hip arthroplasty at Rancho Los Amigos Medical Center between 1972 and 1978. The 4.5-year and 9.2-year results form the basis for comparison.

Management of ipsilateral supracondylar femur fractures following total knee arthroplasty

Abstract: A complete review of the literature revealed 195 fractures in 12 published studies of ipsilateral supracondylar femur fractures occurring about a total knee arthroplasty. This review included general surveys, multicenter studies, and case reports. Based on these studies, the authors divided the fractures into nonoperative and operative treatment groups. The fracture types were also subclassified into nondisplaced (Neer type 1) and displaced (Neer types 2 and 3). Statistical analysis of each type of fracture in terms of the various treatments and clinical outcome was performed. This study revealed satisfactory results in 83% of the patients with nondisplaced fractures that were treated without surgery. In contrast, 64% of all patients with displaced fractures that were treated with or without surgery had satisfactory outcomes. This difference is statistically significant (P < .05). Of the patients with displaced fractures, nonoperative versus operative results were not statistically significant (P < .9) (67% satisfactory vs 61%). A treatment algorithm is proposed based on the above data.

Constrained acetabular components

Abstract: Between May 1987 and October 1990, 21 constrained acetabular components were used in revision total hip arthroplasty at the University of California, San Francisco. In 18 patients, the device was placed for a chronically dislocating total hip arthroplasty. In the remaining three, intraoperative instability during revision total hip arthroplasty necessitated its use. At the minimum 2-year follow-up evaluation (average, 31 months; range, 24–64 months), 15 patients (71%) experienced no further dislocations or subluxations. There were eight dislocations in the remaining six patients (29%). The average Harris hip score at the follow-up evaluation was 76 points (range, 32–100 points). For those patients who redislocated (n = 6), an increased acetabular abduction angle of the metallic acetabular cup, averaging 70°, was the only predictive factor of failure of the constrained cup ( P

Fractures of the ipsilateral femur after hip arthroplasty. A statistical analysis of outcome based on 487 patients.

Abstract: A complete review of the literature revealed 487 patients in 26 published reports with ipsilateral femur fractures occurring about the femoral prosthetic stem. This review included general surveys, multicenter studies, and case reports. Based on these studies, the authors divided the fractures into six types: type 1, intertrochanteric; type 2, proximal femur; type 3, spanning the prosthesis tip; type 4, distal to the prosthesis tip; type 5, comminuted blowout; and type 6, supracondylar. Type 1–5 fractures were stratified into the following treatment groups: traction, casting and partial weight bearing, cerclage wiring, screw/plate fixation, long-stem revision with plus/minus supplementation fixation or bone-graft, and other less frequently reported techniques. A statistical analysis of each type of fracture in terms of the various treatments used and the clinical outcome was performed. The best results based on the literature would be cerclage wiring or long-stem revision for types 2, 3, and 5 fractures ( P P

Midterm results (5.5–10 years) of acetabular allograft reconstruction with the acetabular reinforcement ring during total hip revision

Abstract: Acetabular reconstructions using frozen femoral head allografts and the acetabular reinforcement ring of M. E. Mueller (Protek AG, Bern) have been analyzed after an average follow-up period of 7.2 years (range, 5.5-10 years) in 27 patients/hips. The deficiencies, according to the American Academy of Orthopaedic Surgeons classification, were 1 segmental, 14 cavitary, and 12 combined cavity and segmental. Twenty-two (82%) of the reconstructions were classified as adequate and five (18%) as inadequate based on the operative report and radiographic assessment, including anteroposterior, oblique, and lateral views. Reconstructions were considered adequate if an appropriate sized ring had been used in accordance with the recommendations of the authors (contact on host pelvic bone cranially, posteriorly, and inferomedially). Radiographic evaluation revealed acetabular component migration of more than 2 mm in 12 reconstructions (44%). Of these, cranial migration averaged 4 mm (range, 2-9 mm) in inadequate reconstructions, whereas it averaged only 2 mm (range, 1-4 mm) in adequate reconstructions. The incidence of migration in adequate reconstructions for segmental only and combined cavitary and segmental defects was 6 of 12 (50%), whereas it was 1 of 10 in reconstructions of cavitary deficiencies. Kaplan-Meier survivorship analysis revealed a 79.6% probability of survival at 10 years with revision as the endpoint for failure. It is concluded that durability of the reconstruction can be expected if support of the metallic reinforcement device is provided by host-bone. Segmental and combined deficiencies may require additional internal fixation by plates and screws.

Severe polyethylene wear in total hip arthroplasty. Observations from retrieved AML PLUS hip implants with an ACS polyethylene liner.

Abstract: A retrospective review was performed of 94 consccutive Anatomic Medullary Locking Plus (AML +. DePuy, Warsaw, IN) cementless acetabular components implanted between January 1988 and January 1990. All acetabular cups utilized the Acetabular Cup System (ACS) polyethylene liner (Depuy). Of these hips, 72 had been followed for more than 2 years (average, 43 months). There have been 15 (21%) clinical failures, all due to catastrophic wear of the acetabular polyethylene component surfaces. Of the 15 failures, clinical symptoms were absent in 7, an audible squeak was present in 3, and 5 patients reported having pain. All clinical failures had accelerated acetabular wear necessitating revision. Patients in the failure population were younger (56 years vs 62 years) than the remainder of the patients, and had greater cup abduction angles (55° vs 49°). All of the failed ACS polyethylene components had a 32 mm inner diameter articulating surface. The AML+ acetabular component outer diameter averaged 56 mm (range, 50–64 mm). Six of 15 failures occurred in cups 58 mm or larger. Acetabular wear in the failure group was 0.77 mm/y (average). The incidence of acetabular (78%) and femoral (71%) osteolysis in the failure population is alarming. The rate of failure (21%) at 46 months of the AML+ acetabular component with the ACS polyethylene liner appears to be related to design. The ACS design is flawed by a lack of hemispherical geometry, leading to failure at the superior rim with penetration of the femoral head through the polyethylene and against the metal shell. All patients with total hip arthroplasties of this design, regardless of implant size, should be carefully observed for evidence of polyethylene wear.

Primary total hip arthroplasty using noncemented porous-coated femoral components in patients with osteonecrosis of the femoral head

Abstract: Ninety consecutive total hip arthroplasties in 73 patients with osteonecrosis of the femoral head yielded 81 hips in 64 patients (37 men and 27 women) available for evaluation after a 4–8-year follow-up period. The average age at surgery was 39.9 years (range, 20–66 years). Osteonecrosis etiology was idiopathic in 13 hips, alcohol-induced in 15, femoral neck fracture in 12, and slipped capital femoral epiphysis in 2. The remaining 39 cases were related to steroids, which were administered for a variety of reasons. Two types of noncemented, porous-coated, straight-stem femoral components and three types of acetabular components were utilized. Good or excellent clinical results were recorded in 80.2% of the patients. Average Harris hip scores improved from 52.9 to 87.9 points. Nine patients required revision of at least one component and were significantly younger than those with unrevised components. A revision rate of 24.1% was recorded in patients under 35 years of age at the time of primary surgery. Good or excellent clinical results were seen in 92.3% of the idiopathic cases, 86.7% of the alcohol-induced cases, 77.8% of the renal transplant cases, and 62.5% of the systemic lupus erythematosus cases. The overall mortality rate at the follow-up evaluation was 14%; it was 50% in renal transplant patients. Analysis of the clinical results based on the implants showed no significant differences in Harris hip scores or pain and function scores. While total hip arthroplasty using noncemented porous-coated femoral stems appears to give better results than cemented procedures in patients with osteonecrosis of the femoral head, the results appear to be inferior to those reported in patients with other diagnoses.

Charnley low-friction arthroplasty of the hip. Twenty-year results with cement.

Abstract: The first 333 Charnley (Thackray, United Kingdom) total hip arthroplasties performed at the Mayo Clinic between 1969 and 1970 have been followed since that time. One hundred twelve patients (112 hips) remain alive at 20 years. Clinical results remain excellent. The Mayo clinical and roentgenographic hip scoring system rates the results as good to excellent in 39 of 69 hips (with all necessary data to calculate the entire score), fair in 13 hips, and poor in 17 hips. The clinical score alone showed satisfactory results in 77 of 112 hips. Some clinical deterioration was attributed to the advancing age of the patients (mean age at final follow-up evaluation, 84 years). Probable roentgenographic loosening (component migration, complete bone-cement interface, radiolucent line greater than 1 mm, cement fracture) was noted in 12 of 69 acetabular components (17%) and 28 of 69 femoral components (36%). Two patients had required revision since the last report at 15 years for a total of 38 patients (32 revised, 4 Girdlestone arthroplasties, 2 stem fractures not yet revised). The probability of surviving 20 years without revision of the components was 84% (83% for men, 85% for women). The rates of loosening, revision, and failure (revision, Girdlestone, or symptomatic loosening) remain linear over 20 years of follow-up evaluation. If the probability of revision is based on patient age at the time of the initial total hip arthroplasty, there is a significantly increased probability of revision in those patients less than 59 years of age (27%) compared to those 59–65 years of age (13%), 65–70 years (7.5%), and over 70 years (12%).

Posterior cruciate function following total knee arthroplasty. A biomechanical study

Abstract: The strain developed in the posterior cruciate ligament (PCL) of eight fresh cadaveric knees was measured before and after total knee arthroplasty using a loading technique that simulated stair ascent and descent. Each knee was instrumented with a Hall Effect strain gauge (Micro-Strain, Burlington, VT) in the PCL, a load cell in the quadriceps tendon, an electrogoniometer, and an array of linear displacement transducers to measure femoral rollback. Testing was undertaken with each knee in its normal state with the anterior cruciate cut and with a cruciate-retaining prosthesis, a cruciate-excising prosthesis, and a cruciate-substituting prosthesis. Normal PCL strain levels were produced in only 37% of the trials following implantation of the cruciate-retaining knee arthroplasties. With a cruciate-retaining prosthesis, femoral rollback decreased by an average of 36% and was associated with a 15% loss in extensor efficiency. In the procedures performed with excision of the PCL, rollback decreased by 70% and extensor efficiency by 19%. Cruciate substitution resulted in a 12% loss in rollback and an 11% decrease in extensor efficiency. The strain developed within the PCL during knee flexion was found to be extremely sensitive to the thickness of the polymeric tibial insert. In the majority of cases, it was not possible to restore normal ligament loading with flexion while simultaneously maintaining acceptable varus/valgus stability of the knee joint. Using a range of contemporary knee arthroplasties, the authors were unable to consistently reproduce normal function of the PCL.

A quantitative in vitro assessment of fit and screw fixation on the stability of a cementless hemispherical acetabular component

Abstract: This investigation quantifies in vitro the effect of component fit, as well as the effect of adjuvant screw fixation, on the initial stability of cementless hemispherical titanium acetabular total hip arthroplasty components and assesses apposition of the acetabular components to bone. Six, fresh human hemipelvi (3 matched pairs) were harvested at autopsy. Titanium alloy acetabular components with a porous surface of commercially pure titanium fiber mesh (Harris Galante Porous acetabular components, Zimmer, Warsaw, IN) were used for implantation. Initially, each acetabulum was underreamed to achieve a 2 mm press-fit with the acetabular component. Pressure-sensitive film had been placed along the dome and medial wall at the bone-implant interface to assess the completeness of seating. After the implant was impacted into the acetabular cavity, relative motion between the implant and bone was measured during simulated single leg stance. Adjuvant fixation of the implant was then obtained with the insertion of four 6.5 mm cancellous screws. High-contrast roentgenograms of the specimens in multiple views were obtained after initial cup insertion and again after screw insertion. The stability of each implant under load was measured with four, three, two, one, and no screws in place. Further reaming of the bone was done to create a 1 mm press-fit. The sequence was then repeated. Further reaming was done to create an exact-fit and the sequence was repeated again. Under these conditions, 1 mm press-fit with or without screws provided the optimum combination of fit stability.(ABSTRACT TRUNCATED AT 250 WORDS)

High hip center in revision arthroplasty

Abstract: What is the effect of superior placement of the acetabulum in complex hip reconstruction? Twenty-two patients (23 cases) had revision hip arthroplasty with superiorly placed porous-coated components without bone-grafts. Cemented femoral components were used in 21 cases and ingrowth components in 2. The average vertical height (corrected for magnification) was 36.8 mm from the interteardrop line, compared to a contralateral normal height of 12.1 mm. Three patients were deceased. The remaining 19 patients (20 hips) had a minimum 2-year follow-up period (average, 35 months). Fourteen hips had two or more previous surgeries. Seven acetabular components had thin (< 1 mm), nonprogressive, incomplete radiolucent lines. One acetabulum had a complete 1 mm radiolucent line in an asymptomatic patient. The remaining 12 acetabular components had no evidence of radiolucent lines and none of the acetabular components migrated. One hip with a cemented femoral component had evidence of possible loosening. Two cemented femoral components had evidence of definite loosening, one with minimal clinical symptoms and the other was revised to a long stem at 14 months after revision. Of the two ingrown femoral components, one had initial subsidence of 1.5 cm and both had thigh pain. All other patients had improved from their preoperative status; however, 4 of 20 hips had moderate to severe pain. Superior cup position did not result in concomitant lateral position. With a short-term follow-up period however, vertical displacement alone resulted in high loosening rates, with 25% for the femur and 5% for the acetabulum.

High placement of porous-coated acetabular components in complex total hip arthroplasty

Abstract: The authors retrospectively evaluated the results of 56 hips in 51 patients with an acetabular deficiency who had a total hip arthroplasty with a porous-coated, cementless acetabular component implanted at a high hip center. Forty-nine cases were revisions and seven were primary operations. The mean height of the hip center was 43 mm above the interteardrop line compared to 14 mm for the anatomic center, threefold higher than normal. In contrast, the mean horizontal locus was reduced compared to normal (33 vs 37 mm for the anatomic center). Sixteen acetabular components were small (46-48 mm o.d.) and eight were miniature (40-44 mm o.d.). Despite superior placement of the acetabular component, 32 limbs were lengthened by the procedure. The mean preoperative Harris hip score was 51 (range, 28-93). At a mean follow-up period of 40 months (range, 24-64 months), the mean Harris hip score was 86 (range, 36-100). In 23 hips no radiolucent lines were present at the interface of the bone to the porous mesh, and 33 hips had a thin (0.5 mm), nonprogressive radiolucent line in one or more zones. No acetabular component had migrated and no problems occurred with the screws. Four hips (3 revisions and 1 primary operation) had a complete radiolucent line on one oblique view of the acetabulum. No acetabular component has been revised for loosening.(ABSTRACT TRUNCATED AT 250 WORDS)

The Harris-Galante porous acetabular component press-fit without screw fixation. Five-year radiographic analysis of primary cases.

Abstract: One hundred twenty-two primary total hip arthroplasties were followed for an average of 56 months (range, 48-66 months) in which the Harris-Galante (Zimmer, Warsaw, IN) porous ingrowth acetabular component had been press-fit into the innominate bone without screw fixation. There were no acetabular fractures. No socket was revised for loosening and none were radiographically loose. There was no evidence of disruption of the titanium porous mesh. There was no acetabular osteolysis. Compared to the authors' series of primary hip reconstructions using this same prosthesis inserted with line-to-line reaming and screw fixation, the data indicate that the tight peripheral fit associated with the press-fit technique is effective in reducing both the incidence and extent of bone-implant radiolucencies. However, the increased incidence of radiolucencies near the apex of the acetabulum also suggest that initial contact of the porous surface with live acetabular bone at this location is desirable in order to obtain and maintain an optimal bone-implant interface. Additional studies are necessary to further establish the relationship between the initial fit and long-term fixation of cementless acetabular components. Based on the data and other considerations for eliminating both vascular risk and the potential for fretting wear between the screws and shell, the authors recommend press-fitting without screw fixation for this acetabular component in primary cases when anatomy and bone stock permit. Full seating of the component is recommended in order to obtain dome contact.

Osteolysis of the distal femur after total knee arthroplasty

Abstract: An 11.1% incidence of femoral osteolysis (30 cases in 28 patients) was identified in a series of 271 primary total knee arthroplasties. Two minimally constrained total knee designs (Synatomic [Depuy, Warsaw, IN] and Porous-Coated Anatomic [PCA, Howmedica, Rutherford, NJ]) were used in this patient population. Femoral osteolysis was observed in 26 Synatomic and 4 PCA knees. The average follow-up period was 52 months (range, 24–96 months). Osteolytic lesions were identified radiographically, adjacent to the nonporous-coated (smooth) regions of the anterior and posterior flanges of the Synatomic and PCA femoral components. The average time to the diagnosis of femoral osteolysis was 31 months (range, 7–96 months). The average patient age at the time of primary total knee arthroplasty was 63 years (range, 43–83 years) and the average weight was 180 lb. (range, 107–278 lb.). Sixteen of the 30 cases were in men. All of the cases with femoral osteolysis had cementless implantation. Tissue specimens were obtained from the 18 cases requiring revision. Implants remained in situ an average of 66 months (range, 15–96 months) prior to revision. In 16 of the 18 cases revised, the femoral component was clinically and radiographically stable. Six of 18 cases were revised for severe osteolysis. The remaining 12 cases were revised for failed metal-backed patellae, failed cementless tibial fixation, or advanced polyethylene wear. Wear of the thin tibial inserts and patellar components were the two sources of particulate polyethylene. Polyethylene debris was observed in all tissue specimens. In cases with failed metal-backed patellae or impingement of the tibial locking pin-and-clip, fine metallic debris was also noted in tissue specimens. Microscopic evaluation of the osteolytic tissue revealed a florid histiocytic response with occasional giant cells. Intracellular submicron particulate polyethylene was identified with polarized light microscopy and oil-red-O staining techniques. In the study population, statistically significant factors associated with femoral osteolysis included male gender (P < .05), younger age (P < .05), increased patient weight (P < .05), positive tibial osteolysis (P < .001), osteoarthritis (P < .07), and length of time in situ (P < .001). In addition, patients with a Synatomic prosthesis were at increased risk for osteolysis compared to patients with a PCA device (P < .02). The authors postulate that histiocytic granuloma gained access to the proximal femur primarily via the unbonded interface between the smooth metal and bone.

Costs of elective total hip arthroplasty during the first year. Cemented versus noncemented.

Abstract: The cost-effectiveness of the Mallory Head (Biomet, Warsaw, IN) cemented versus noncemented total hip arthroplasty was determined as part of a randomized trial. Costs were assessed during the first postoperative year. In-hospital resource use was determined using a chart review of 60 randomly selected patients. Costs were determined using a fully allocated costing model. Outpatient resource use was determined using patient diaries, and appropriate costs were allocated for outpatient visits, admissions to hospital, and patient-borne costs. There was no difference in costs between the cemented and noncemented prostheses. The average cost of the initial hospitalization was $9,990 (1988 Canadian dollars), and outpatient costs during the first year were $1,137 (total cost during the first year was $11,127). The cost per quality adjusted life year was $27,139 during the first year and $8,031 during the first 3 years.

Radiographic assessment of cementless femoral components. Correlation with intraoperative mechanical stability.

Abstract: The correlation between preoperative radiographic findings and intraoperative testing for stability was evaluated for 75 cementless femoral components. Fourteen of 45 porous-coated prostheses were unstable. The following radiographic signs were correlated with instability in order of significance: radiolucent lines at the bone-prosthesis interface covering greater than 50% of the porous interface, a distal pedestal, calcar hypertrophy, poor implant-cortical contact, and varus component alignment. Signs consistent with implant stability were good implant-cortical contact, spot welds, and calcar atrophy. Preoperative radiographs have predictive value in assessing the mechanical stability of the cementless femoral component at the time of surgery.

Peripheral neuropathies following total hip arthroplasty.

Abstract: The authors reviewed the complication records following total hip arthroplasty at their institution between January 1976 and July 1989. Forty-two patients (12 men and 30 women) with 45 neurologic complications were identified following 7,133 consecutive total hip arthroplasties; an incidence rate of 0.63%. The average age of these patients was 58 years (range, 27–81 years). Thirty-four nerve injuries were noted in the lower extremity (0.48% incidence rate) and 11 in the upper extremity (0.15% incidence rate). The majority of patients (64%) with neurologic injury to the upper extremity had the diagnosis of inflammatory arthritis. The common peroneal was most often involved in the lower extremity. The ulnar nerve was most commonly involved in the upper extremity. The pathogenetic factors leading to neurologic injury in the majority of patients were not clearly established. Leg lengthening did not seem to be a major cause. The prognosis of patients with nerve palsy of the upper extremity is favorable compared with injury to the lower extremity. Similarly, the percentage of patients with a permanent neurologic deficit was lower in the primary surgery group (27%) compared with the revision/reoperation group (43%). The overall percentage of permanent nerve palsy was 33%. Female patients, for unclear reasons, appear to have a higher risk for neurologic injury. Also, the risk of neurologic injury following total hip arthroplasty appears to be higher with revisions/reoperations and with an inexperienced surgeon.

Revision total hip arthroplasty: Long-term results without cement

Abstract: The authors present their results for cementless femoral revision arthroplasty using extensively porous coated implants. Patients have been prospectively followed for 5 to 11 years (mean 7.4 years). The revision rate was 5.7%, and the radiographic loosening rate was 1.1%, to give a mechanical failure rate of only 6.9%. As a result of the revision procedure, the pain level was improved for 89.1% of the patients, walking status was improved for 82.8% of the patients, and functional level was improved for 88.5% of the patients. These results compare very favorably with any reports on revision arthroplasty using cement with a similar length follow-up.

Suboptimal (thin) distal cement mantle thickness as a contributory factor in total hip arthroplasty femoral component failure. A retrospective radiographic analysis favoring distal stem centralization.

Abstract: One hundred cemented total hip arthroplasties (THAs) were evaluated regarding the potential benefit of THA femoral component distal stem centralization, specifically regarding cement mantle thickness. Factors potentially predictive of femoral component mechanical loosening, both relating (22 factors) and not relating (41 factors) to cement, were analyzed on initial postoperative radiographs. Nine THAs with femoral component mechanical failure (group 1) were compared to (1) 88 non-failed THAs (group 2) and (2) 9 matched-paired, nonfailed THAs (group 3). Significant differences were evident regarding minimum and maximum cement mantle thickness in Gruen zone 5 and combined zones 5/6 (groups 1 vs 2 and groups 1 vs 3), with failed femoral components having thinner cement mantles. Discriminate analysis determined minimum cement mantle thickness in zone 5 to be the factor most predictive of femoral component failure. These data indicate that a suboptimal (thin) cement mantle at the medial diaphysis (Gruen zones 5 and 6) contributed to femoral component mechanical loosening in this THA series. This relationship may not pertain to femoral stems of different materials or cross-sectional characteristics. Many THA systems currently provide for a method of centralization of the femoral component distal stem as a mechanism to ensure an adequate circumferential distal cement mantle. Continued investigation into techniques directed toward centralization of the distal femoral stem is warranted by the findings of this study.

Morphology-mechanical property relations in trabecular bone of the osteoarthritic proximal tibia.

Abstract: Alteration of morphologic and mechanical properties of trabecular bone in the osteoarthritic proximal tibia may be a contributing factor in tibial component loosening. To explore this issue, the authors performed tissue property measurements, morphologic analysis, and mechanical testing of subchondral, epiphyseal, and metaphyseal trabecular bone specimens retrieved from six human proximal tibias exhibiting a range of medial unicondylar osteoarthritic degeneration. Apparent density in the proximal tibia was altered according to varus misalignment and medial subluxation associated with medial osteoarthritis of the knee. In subchondral bone, a decrease in tissue mineralization contributed to a significant reduction in axial mechanical properties with degenerative disease (P < .0005). In epiphyseal and metaphyseal bone, trabecular thickness and the number of trabeculae increased linearly with volume fraction, providing a power law relationship between axial elastic modulus and apparent density (R2 = .84). Average elastic properties of the tibial epiphysis and metaphysis were not reduced by degenerative disease (P < .05). The results suggest that absolute minimization of tibial resection might not be an optimal strategy for tibial component fixation and that mechanical properties of the tibial resection surface are more homogeneous in planes parallel to the joint surface than in a plane normal to the longitudinal axis of the tibia.

Effect of rotation on the radiographic appearance of the femoral canal

Abstract: Radiographic templating is a key element of preoperative planning for cementless total hip arthroplasty, and it aids in the selection of an appropriate implant. Frequently, the radiographic projection of the proximal femur does not correspond to that of the femoral prosthesis on its template due to variations in patient positioning. This discrepancy is a potential source of error when predicting which femoral component will best fit within the femoral canal. To evaluate the effect of femoral rotation on the size and shape of its radiographic image, anteroposterior and lateral radiographs of 12 femora were prepared over a range of positions. Several medullary canal dimensions were measured for each projection. The changes in these dimensions were compared using the image at neutral rotation as a reference. Each femur was then implanted with an appropriately sized cementless prosthesis to determine its actual rotational orientation in the canal. On the anteroposterior projection, statistically significant changes in the width of the proximal canal with femoral rotation were noted. There was no statistically significant change in distal canal dimensions with rotation. On the lateral projection, the dimensions of the proximal canal changed significantly with internal rotation; however, external rotation had no effect on canal dimensions. In general, the magnitude and direction of the canal dimensions were highly variable. The final rotational orientation of the femoral component in the canal was quite variable with respect to the plane of the femoral neck. Errors in implant selection may be due to excessive reliance on preoperative templating, which can be misleading because of femoral rotation.

Version of the osteoarthritic knee

Abstract: Version of normal and osteoarthritic knees is evaluated by computed tomography in this study. Version of the knee is defined as the static rotation of the tibia with respect to the femur in full knee extension. It is measured as the difference between the transverse axes of the femoral condyles and tibia. The average knee version, or external rotation of the tibia with respect to the femur across the normal knee, was 0°. Version of the osteoarthritic knee was 5°. Rotation of the tibia with respect to the femur across the extended osteoarthritic knee is a relationship that will affect the placement of components in total knee arthroplasty. This relationship should be addressed in alignment instrumentation and technique to avoid component malalignment in total knee arthroplasty.

Cementless or hybrid total elbow arthroplasty with titanium-alloy implants

Abstract: Twenty-six patients (32 elbows) with rheumatoid arthritis had a total elbow arthroplasty with insertion of a cementless prosthesis. The humeral component was made of titanium alloy and it was fixed without cement in all elbows. The patients were followed for an average of 3 years 1 month (range, 2 years 2 months to 4 years 4 months). A good result was seen in 25 elbows, a fair result in 2, and a poor result in 5. The reason for the poor results was a breakage of the humeral component at the junctional portion of its stem. In all five of these elbows a marked resorption of bone mass within the condylar portion of the humeral component was observed on the lateral radiograph. The five elbows with a poor result had a revision operation, and in each of these black staining of the soft tissues within the joint was seen. This tissue metallosis due to wear debris of the titanium alloy was responsible for the osteolysis within the condylar portion. It became clear from this study that even in a non-weight-bearing joint, such as the elbow, titanium alloy may wear and result in tissue metallosis when used as a bearing surface of the implant. However, it was also found that in the majority of the elbows an establishment of the biologic fixation of the porouscoated stem could be achieved by use of this alloy.

Activity and socket wear in the Charnley low-friction arthroplasty.

Abstract: A clinical study was undertaken to assess the influence of patient-related factors on wear of the socket in Charnley low-friction arthroplasty. One hundred nine arthroplasties in 79 patients were reviewed at an average of 10.3 years. A new method of activity assessment was designed and used to estimate the distance walked by each patient. This method was validated by a pedometer that recorded the time taken by each patient to walk 20 m. Activity level was related to the amount of movement at the level of the prosthetic articulation by calculating the sliding distance of a point at the center of the surface of the head of the femoral component. Wear was found to correlate with patient activity, but not with the physical characteristics of the patient or the time since operation.

Primary Total Knee Arthroplasty in the Elderly

Abstract: In a retrospective study, the authors investigated the outcome of primary total knee arthroplasty in patients aged 75 years or older. There is an increased risk of perioperative mortality and medical morbidity, but not surgical morbidity. The results were equal to the younger control group in terms of patient satisfaction, pain relief, stability, range of motion, residual degree of flexion contracture, and extension lag. Mobility was less impressive in the elderly group; factors included were ability to walk, use of walking aids, gait, ability to get out of a chair, and ability to climb stairs.

Global rating systems used in assessing knee arthroplasty outcomes.

Abstract: Global, aggregated knee rating systems are commonly used to assess patient outcomes following knee arthroplasty. In this study, the authors performed a systematic literature search and found that 17% of the English-language studies addressing primary knee arthroplasty reported on patient outcomes following the procedure using a standardized global rating system. The authors describe, in detail, the rating systems' development and format. This study found 34 different rating systems represented in the literature from 1972 to 1992. Great variability was found in the rating systems' design and utilization. Additionally, these condition-specific, physician-based rating systems did not have documented studies demonstrating their reliability or validity. Future research will need to address the issues of selecting and aggregating outcome measures and of deriving any necessary weighting schemes. The ability of researchers to compare patient outcomes across studies will be enhanced when there is consistency in reported outcome measures.

Cementless porous-coated anatomic medullary locking total hip prostheses.

Abstract: The authors studied 50 consecutive and nonselected patients (52 hips) who were followed for a minimum of 7 years (range, 84–89 months) after they had a primary total hip arthroplasty with an uncemented Anatomic Medullary Locking (DePuy, Warsaw, IN) hip system. The average age of the patients at operation was 47.6 years (range, 19–88 years). The operative diagnoses were: avascular necrosis of the femoral head in 18 hips (34%), osteoarthritis in 16 (31%), fracture of the femoral neck in 14 (27%), and miscellaneous in 4 (8%). The average preoperative Harris hip score was 59 points (range, 6–67 points) that improved to 91 points (range, 69–100 points) at the 7-year follow-up examination. To assess the adequacy of intramedullary fit, the fit of the stem at the proximal canal and isthmus level was evaluated. Forty-one hips (79%) had a good press-fit at both the proximal canal and isthmus level, five hips (10%) had a good press-fit at the proximal canal only, and the remaining six hips (11%) had a poor fit at both the proximal canal and isthmus level. Of the 46 hips that had a good press-fit at the proximal canal and/or isthmus level or proximal canal only, 32 (70%) had bone ingrowth and 14 (30%) had stable fibrous tissue ingrowth. Of the remaining six hips with a poor press-fit at both the proximal canal and isthmus level, three (6%) had stable fibrous tissue ingrowth and another three (6%) were unstable. Of the three hips (6%) with femoral component loosening, one was revised and the other two were asymptomatic. There was an alarmingly high incidence of perioprosthetic osteolysis in our series: 16 hips (31%) had acetabular and femoral osteolysis and 13 hips (25%) had femoral osteolysis only. Also, there was a strikingly high incidence of polyethylene-liner wear (12 hips or 23%). Although the incidence of component loosening was low, a high incidence of periprosthetic osteolysis and excessive wear in the polyethylene liner remain challenging problems after insertion of the cementless Anatomic Medullary Locking prosthesis.