Sanford H. Anzel

The Influence of Fixed Rotational Deformities of the Femur on the Patellofemoral Contact Pressures in Human Cadaver Knees

Patellofemoral contact pressures resulting from fixed rotational deformities of the femur were studied in human cadaver knees. The increase in the degree of fixed rotational deformities of the femur results in a nonlinear increase in patellofemoral contact pressures on the contralateral facets of the patella (i.e., external rotational deformity resulted in a contact pressure increase on the medial facet, and internal rotational deformity resulted in a contact pressure increase on the lateral facet of the patella). With the initial isometric tension of 200 N in the quadriceps tendon for 30 degrees, 60 degrees, 90 degrees, and 120 degrees knee flexion, the peak contact pressure showed no significant differences between the medial and lateral facets of the patella in its anatomic position. At 20 degrees of rotational deformity of the femur, only a slight increase was noted for the tension in the quadriceps tendon and the patellofemoral contact pressures on the contralateral facets of the patella. However, at 30 degrees rotational deformity of the femur, both the external and internal rotational deformity of the femur showed a significant increase in the tension of the quadriceps tendon and the patellofemoral contact pressures on contralateral facets of the patella. The greatest increase in patellofemoral contact pressures was observed at 30 degrees and 60 degrees knee flexion for both the external and internal rotational deformity of the femur. The external rotational deformity of the femur for all knee flexion angles showed significantly higher peak patellofemoral contact pressure increases on the medial facet of the patella as compared with the lateral patellofemoral contact pressure increase resulting from internal rotational deformity of the femur.

Fat embolism syndrome following the intramedullary alignment guide in total knee arthroplasty

Fat embolism syndrome (FES) is a well-known complication of total hip arthroplasty (THA). FES occurs less frequently in total knee arthroplasty (TKA) than in THA. A 67-year-old woman developed FES after placement of the intramedullary femoral alignment guide during TKA. The diagnosis is based upon a subtle, but significant change in the oxygen saturation after placement of the guide. This potentially fatal complication may be avoided with a simple precautionary step of intramedullary canal marrow aspiration prior to placement of the alignment guide pin.

Patellofemoral Joint Kinematics and Contact Pressures in Total Knee Arthroplasty

Patellofemoral joint kinematics, contact areas, and contact pressures were measured concomitantly before and after total knee arthroplasty in 10 fresh frozen human cadaver knees using an Instron machine, a custom patellofemoral joint testing jig, axial bone markers, a continuous video digitizing system, and Fuji pressure sensitive film. The implant used in this study was the Kirschner Performance Knee System with an all polyethylene, domed patellar component. For all tests, the patella was aligned in its anatomically neutral position. Patellofemoral joint contact areas decreased as much as 19-fold after total knee arthroplasty. Mean patellofemoral joint contact pressures increased as much as 32-fold, and peak patellofemoral joint contact pressures increased as much as 22-fold after total knee arthroplasty. No statistically significant differences between preoperative and postoperative specimens were observed with respect to the patellofemoral, patellotibial, or patellar tilt angles from 30° to 120° knee flexion. Thus, the elevated patellofemoral joint contact pressures observed after total knee arthroplasty in vitro are not a primary consequence of iatrogenically altered patellofemoral kinematics.

Infected Total Hip Arthroplasty Due to Actinomyces Israelii after Dental Extraction: A Case Report

Late infection of a total hip arthroplasty after dental extraction has been reported, but never with an organism that is found exclusively in mouth flora. Actinomyces israelii is an organism responsible for dental caries. A 61-year-old woman developed an infected total hip arthroplasty after dental work. She denies ever being instructed to take prophylactic antibiotics by her orthopedic surgeon, by her internist, or by her dentist. Considering the extensive morbidity and potential mortality of an infected hip prosthesis, it is essential that all physicians are aware of the indications for antibiotic prophylaxis following joint arthroplasty. Recommendations for antibiotic prophylaxis for dental manipulation are a loading dose of 2.0 g of penicillin V orally or 1.2 million U of aqueous procaine penicillin G with 1.0 gram of streptomycin given intramuscularly 30 minutes before dental work, followed by four doses of 0.5 g of penicillin V orally every six hours.

UCI knee replacement.

Between March 9, 1972 and December 31, 1973, a total of 103 UCI knee replacements were performed. Follow-up data are available on 83 knees with an average follow-up of 33 months. Patient evaluation of the end results indicates that 78.3 per cent were better, 9.6 per cent unchanged, and 12.1 per cent worse. Patient evaluation of their own knee function averaged 55 per cent preoperatively and 79 per cent postoperatively. Patients were also evaluated on a 100 point Modified Larson Analysis Form. The average preoperative score was 46, and the average postoperative score was 70. There were six (5.8%) biological complications in the 103 knee replacement. Biological complications included infections, wound healing problems and unexplained pain. Mechanical complications were seen in 18 (17.4%) knees, and included knee instability, tibial component loosening or deformation, and patellar problems. Additional surgery was required in 18 (17.4%) knees. Failure of the procedure eventually requiring removal of the prosthesis and fusion or amputation occurred in 4 (3.9%) knees. The intermediate-term results of UCI knee replacement have been clinically satisfactory. We currently recommend consideration of this procedure for patients with disabling arthritis of the knee.

Results of Patellar Realignment in Patients Older than Thirty

A retrospective study of patellar realignment procedures was performed on patients over the age of 30 years, with a mean follow-up of 32 months on 16 operated-on-knees in 14 patients. The best results were achieved in patients with preoperative apprehension and compression signs, as well as a typical history for patellar subluxation. when these signs were absent after operation, the result was better than seen in patients whose clinical signs persisted. There was no correlation of results with the grade of chondromalacia noted at surgery. Good or excellent results were achieved in about 75% of the patients. An accurate preoperative diagnosis in the selection of operative candidates is imperative.

A Review of Delayed Unions of Open Tibia Fractures Treated With External Fixation and Pulsing Electromagnetic Fields

Seventeen cases of open tibia fractures complicated by delayed union were reviewed. Only severe injuries requiring external fixation for tissue management and multiple surgical procedures were included in this study. All were ultimately treated with pulsing electromagnetic fields. Our purpose was to evaluate the efficacy of electrical stimulation in these cases and any synergism with combined surgical procedures. Fifteen of 17 cases (88.2%) united within an average of 5.65 months after electrical stimulation was implemented. The average time interval from injury to application of electrical stimulatin was 13.75 months. Pin tract infections occurred in an alarmingly high number of patients; however, all responded to treatment. A notable synergistic relationship with bone grafting was found when stimulation was applied postoperatively.

Medial collateral ligament replacement in the rabbit model: A preliminary report

trauma, poses a serious clinical dilemma. In the acute injury, specific surgical approaches and repairs have been delineated which are, in large measure, successful in reconstituting competent support of the knee. However, in chronic ligamentous laxity, the quality and quantity of tissues available for reconstruction may be less than optimal, contributing to compromise of the expected or potential results. In those clinical situations where autogenous tissues have not been adequate, there appears to be a need for a suitable replacement material. As a consequence, biological as well as synthetic substitutes are being sought. When considering any non-autogenous substitute one must be cognizant of the acceptability of the graft material to the host. The ideal graft material must fulfill certain criteria: (1) availability and ease of storage of the material, (2) implantation must be accomplished using presently available techniques, (3) lack of antigenic or carcinogenic properties, (4) incorporation or actual replacement of the graft by the host, (5) the graft must function as a reliable replacement for the lifetime of the host and, (6) the graft must duplicate the mechanical properties of the replaced material. There are two general classes of materials available to fulfill these needs. (1) Synthetic: These have had limited success in serving as

Compression arthrodesis of the ankle following failed ankle arthroplasty using hoffmann® external fixation.

Nine patients with failed Irvine Total Ankle Arthroplasties have been treated by compression arthrodesis with Hoffmann external fixators. Six were men and three were women; ages ranged from 33 to 70 years. An anterior approach was used with application of a Hoffmann external fixator. Three pins were placed in the distal tibia, and three pins in the talus. After six to eight weeks, the fixator was removed. The patients were placed in a short leg walking cast until fusion was complete. All nine ankles fused primarily, in an average of 16.9 weeks (range: ten to 23 weeks). There were two complications of delayed wound closures. There were no problems with pin tract infections or osteomyelitis.