Steven H. Stern

Use of helical computed tomography for the assessment of acetabular osteolysis after total hip arthroplasty.

Background: Acetabular osteolysis is a major problem affecting long-term survival of total hip prostheses. Since lytic lesions may be asymptomatic until extensive bone loss has occurred, early detection of lytic lesions is important. The purposes of this study were to determine the efficacy and potential role of high-resolution helical (or spiral) computed tomography with metal-artifact minimization in the early detection of osteolysis of the pelvis and to use the method to determine if there was a relationship between the extent of osteolysis and the amount of polyethylene wear. Methods: Forty patients (fifty hips) who had undergone primary cementless total hip arthroplasty between 1988 and 1994 were evaluated as part of an ongoing prospective study. These patients had a history of high-level activity that was believed to place them at increased risk for accelerated polyethylene wear. The most recent follow-up radiographs were compared with the three-month postoperative radiographs. Helical computed tomography scans with metal-artifact minimization were made, and evidence of osteolytic lesions on these scans was compared with that on the radiographs. Two-dimensional wear analysis was performed with use of digitized radiographs, and the results were compared with loss of bone volume as calculated from the computed tomography scans. Results: Acetabular lysis was identified on the radiographs of sixteen hips and on the computed tomography scans of twenty-six hips. Radiographs underestimated the extent of the lysis in thirteen of the sixteen hips. There was no correlation (r = 0.036) between linear wear and the measured volume of bone loss, with the numbers available. On the basis of the amount of lysis seen on the computed tomography scans, one patient underwent a revision procedure. Conclusions: Helical computed tomography with metal-artifact minimization is more sensitive for identifying and quantifying osteolysis after total hip arthroplasty than is plain radiography. Since computed tomography scans show both the extent and the location of lytic lesions, they are useful to guide treatment decisions as well as to assist in planning for surgical intervention, when needed, in patients with suspected osteolysis.

Total knee arthroplasty in valgus knees.

One hundred thirty-four total knee arthroplasties in 98 patients with a valgus alignment were analyzed. Knees with a preoperative alignment of 10° or greater anatomic valgus were believed suitable for inclusion. The average follow-up period in these patients was 4.5 years (range, two to ten years). One hundred eighteen knees were implanted with a posterior stabilized prosthesis, eight knees with a constrained implant design, four knees with a total condylar prosthesis, and four knees with a cruciate-retaining design. All components in all knees were cemented. A lateral retinacular release was necessary in 76% of the arthroplasties secondary to intraoperative lateral subluxation of the patella. The ligamentous release for balancing these valgus-deformed knees was done from the femur. There were 95 knees (71%) rated as excellent, 27 knees (20%) as good, eight knees (6%) as fair, and four knees (3%) as poor. Postoperatively, 76% of the knees had a tibiofemoral alignment between 5° and 9° valgus with an overall average of 7° valgus (range, 3° varus to 15° valgus). Total knee arthroplasty is a reliable and durable procedure in the treatment of valgus knee arthritis. However, valgus-deformed knees represent a greater challenge than their varus counterparts to the implant surgeon in terms of the intraoperative balancing required. This may be a function of the greater difficulty in achieving ligamentous equilibrium and the relative rarity of valgus-deformed knees.

Total knee arthroplasty in diabetes mellitus

A retrospective study was done of 59 total knee arthroplasties (TKAs) in 40 patients diagnosed with diabetes mellitus. The overall infection rate was 7%, with an overall revision rate of 10% and an average follow-up period of 4.3 years. Wound complications were present in 12% of the TKAs. The rate of deep joint infections in diabetic patients was statistically higher than the reported incidence of sepsis in nondiabetic patients. Therefore, maximum precautions should be taken for diabetic patients having TKA to minimize both wound complications and joint sepsis.

Cemented Total Knee Arthroplasty for Gonarthrosis in Patients 55 Years Old or Younger

The results of 68 cemented total knee arthroplasties (TKAs) in 50 patients with gonarthrosis who were 55 years old or younger at the time of surgery were reviewed. These patients were operated on between 1979 and 1987 and were followed for an average of 6.2 years. The average age of the patients was 50 years. Patients were evaluated by the Hospital for Special Surgery knee score. The average preoperative score was 53, and the average follow-up score was 90. Overall, 55 TKAs were rated as excellent and 13 as good. Using the knee rating score advocated by the Knee Society, the average postoperative score was 92 for pain and 84 for function. There were four successful reoperations for patellar component loosening, all in metal-backed patellae. The femoral and tibial components in these patients were intact, and at the follow-up period, two knees were rated as excellent and two as good. Detailed roentgenographic evaluation demonstrated that 20% of tibial components had radiolucencies in at least one zone on the anteroposterior roentgenogram and in 11% on the lateral roentgenogram. Femoral radiolucencies occurred in only 2% of knees. Patellar radiolucencies in one or more zones occurred in 20% of knees that had not had patellar revision. No complete or progressive radiolucencies at the bone-cement interface were noted for any component, and no components were considered to be roentgenographically loose. Cemented TKAs can achieve excellent long-term results in patients younger than 55 years old with gonarthrosis of the knee. These results compare with those obtained in published reports on older age groups.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of tibial stem design on component micromotion in knee arthroplasty

Rigid body mechanics with computer data acquisition and analysis techniques were used to determine the three-dimensional motions of any point on the tibial component of a total knee arthroplasty. Three stem configurations were compared: (1) no stem; (2) short stem (40 mm); and (3) long stem (75 mm). In addition, three loading conditions were analyzed for each stem configuration: (1) central loading; (2) posterior loading; and (3) medial loading. The longer stem implants were associated with increased micromotion, especially under eccentric loading. Cemented implants seemed to have more stable fixation, compared with noncemented implants. It was thought that the increased motion was secondary to a toggling of the implant under load, secondary to uneven medullary cortical contact. Overall, the results indicated that short and long stems do not enhance initial fixation with cemented or cementless implantation in routine knee arthroplasty.

Proprioception after arthroplasty: role of the posterior cruciate ligament.

To test the hypothesis that retaining the posterior cruciate ligament during total knee arthroplasty helps preserve the threshold of proprioceptive sensation, a machine was designed that permitted direct measurement of passive angular deflection from a resting point to the threshold of patient perception. Sixty patients with unilateral primary total knee arthroplasties were evaluated; 30 with posterior cruciate ligament retaining prostheses and 30 with posterior cruciate ligament substituting prostheses. All patients had a minimum postoperative followup of 1 year, a good or excellent result as defined by the Hospital for Special Surgery Knee Score, and no evidence of peripheral neuropathy. The gender and age distributions were equivalent between groups. The average threshold of perception for the posterior cruciate ligament retention group was 2.4 °. The average threshold of perception for the posterior cruciate ligament substitution group was also 2.4 °. Substitution or retention of the posterior cruciate ligament makes no clinical difference in proprioception as measured by threshold testing. This study provides new information for surgeons performing total knee arthroplasty to aid in the decision to retain or substitute the posterior cruciate ligament. Previous proprioception evaluation in patients with posterior cruciate ligament retaining versus posterior cruciate ligament substituting arthroplasties, using different testing methods, has revealed different results.

Antibiotic impregnated bone cement in total hip arthroplasty. An in vivo comparison of the elution properties of tobramycin and vancomycin.

A prospective in vivo quantification was performed to measure the elution of tobramycin and vancomycin antibiotics from two commonly used bone cements. Forty patients were divided into four groups: Group I, tobramycin-Simplex; Group II, tobramycin-Palacos-R; Group III, vancomycin-Simplex; and Group IV, vancomycin-Palacos-R. Antibiotic levels were measured from hemovac wound drainage, urine, and serum and compared with control groups who received either intravenous tobramycin or vancomycin. There were no significant differences in daily mean tobramycin levels in hemovac samples between Groups I and II. Tobramycin hemovac levels from Groups I and II were significantly higher than the tobramycin control group. Similarly, no differences were seen in daily mean vancomycin levels of the hemovac samples between Group III and IV; however, the intravenous vancomycin control group had significantly higher levels in the hemovac fluid than Groups III or IV. Tobramycin in the hemovac fluid from Groups I and II was highly bioactive against the control organism. Vancomycin in the hemovac fluid from Groups III and IV had variable bioactivity against the control organism. In 30% of the cases, no vancomycin was detected in the hemovac fluid, and in these cases, the hemovac fluid had no effect on the control organism. Tobramycin elutes to give adequate local tissue levels and releases antibiotic effects when used in an antibiotic bone cement combination. Vancomycin has variable elution properties and is not a predictable additive for the bone cements tested.

Total knee arthroplasty in patients with psoriasis.

Patients with progressive psoriasis have an increased infection rate when having total joint arthroplasty. Therefore, maximum precautions should be taken in the perioperative period as well as with long-term follow-up care to prevent joint sepsis in these patients. In particular, skin care should be meticulous. Special attention should be given to use of a topical corticosteroid or other dermatologic treatment when total joint arthroplasty is considered.

Total knee arthroplasty in elderly patients

The authors examined 98 total knee arthroplasties in 73 patients who were 80 years of age or older at the time of surgery (average, 82 years; range, 80-90 years). The follow-up period averaged 4.5 years (range, 2-12 years). The patients were divided into two groups based on their tibial component design. There were 38 all-polyethylene tibial components in 28 patients and 60 metal-backed tibial components in 45 patients. There were 61 (62%) excellent, 30 (31%) good, 2 (2%) fair, and 5 (5%) poor results. Three of the five poor results required revision for septic failure. Of the knees with an all-polyethylene tibial component, 20 (53%) were rated as excellent, 15 (39%) as good, and 3 (8%) as poor. One of these knees rated as poor required revision for septic failure. The knees with a metal-backed tibial tray had 41 (68%) rated as excellent, 15 (25%) as good, 2 (3%) as fair, and 2 (3%) as poor. Both of the knees with poor results required revision for septic failure. Stratifying the results by component composition revealed 97% survival for both types of tibial trays. These results were obtained at 12 years for the all-polyethylene components and at 8 years for the metal-backed prosthesis. In conclusion, the authors believe that total knee arthroplasty is a reliable and durable procedure in the treatment of knee arthritis in the elderly. Elderly patients may represent a special case because they are generally less active than younger patients and may place less stress on their prosthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Sexual function after total hip arthroplasty

Eighty-six patients who had successful total hip replacement completed questionnaires on their sexual activity. Preoperatively, 46% of patients attributed significant sexual difficulties to their hip disease, whereas only 1% felt that their hips remained a significant source of problems postsurgery. The majority (55%) of patients were able to resume intercourse one to two months postoperation. Male patients were statistically more likely to resume intercourse sooner than their female counterparts. Patients were also questioned about which coital positions they found comfortable after arthroplasty. The supine position (patient on bottom) was the most preferred. The next most comfortable position for males was prone (patient on top), yet for female it was sidelying on the nonoperative hip. In addition, 89% of patients desired more information regarding sexual function postarthroplasty, preferably in the form of a booklet. Therefore, a booklet was written specifically for postoperative patients and their sexual partners.