Showing papers in "Journal of Bone and Joint Surgery, American Volume in 1982"

Dislocations after total hip arthroplasty.

Abstract: During the ten-year period ending in 1978, 10,500 conventional total hip arthroplasties were performed at the Mayo Clinic; dislocation developed after 331 (3.2 per cent) of these procedures. Cross correlations of the data were performed using multivariate analysis. This analysis showed that previous surgery on the hip was the most significant of the factors predisposing to dislocation, the incidence doubling from 2.4 per cent (in hips without previous surgery) to 4.8 per cent (in hips with previous surgery) (p less than 0.001). The dislocation rate was 2.3 per cent after an anterolateral approach and 5.8 per cent after a posterior approach (p less than 0.01). The size of the head of the femoral component was not a strongly influential factor. The incidence of dislocation was 17.6 per cent in the hips that had osteotomy and avulsion of the greater trochanter, compared with 2.8 per cent in those in which the trochanteric osteotomy united (p less than 0.001). Reoperation for instability of the hip was performed in a third of the patients, but in 31 per cent of the patients whose hip was reoperated on the instability persisted after the revision.

The effect of medial meniscectomy on anterior-posterior motion of the knee.

Abstract: We used an in vitro knee-testing apparatus to measure anterior-posterior displacement of the tibia on the femur and the accompanying tibial rotation in response to an applied anterior-posterior force. Testing was performed on nine intact knees, on five knees after medial meniscectomy, on three knees after isolated section of the anterior cruciate ligament, and on eight knees after both excision of the medial meniscus and section of the anterior cruciate ligament. The induced anterior-posterior displacement and the coupled rotation were unaffected by meniscectomy. Isolated section of the anterior cruciate ligament allowed a significant (p less than 0.05) increase in anterior displacement but had no effect on posterior displacement. The coupled internal rotation associated with anterior displacement was lost after section of the anterior cruciate ligament. Excision of the medial meniscus and section of the anterior cruciate ligament allowed significantly (p less than 0.05) greater increases in anterior displacement than those already increased by isolated section of the anterior cruciate ligament.

Variations in the intrinsic mechanical properties of human articular cartilage with age, degeneration, and water content.

Abstract: In a series of 103 specimens from the lateral facet of the human patella, the intrinsic mechanical properties of articular cartilage were measured using a confined compression creep test. By considering the cartilage as a porous, permeable solid filed with fluid, this experimental procedure allowed the determination of the intrinsic equilibrium modulus of the cartilage matrix and its permeability to fluid flow. The intrinsic equilibrium modulus and the permeability both were highly correlated with the water content of the tissue; as water content increased, the matrix of the tissue became softer and more permeable. There was only a marginal decrease in the equilibrium modulus of the tissue with increasing age and surface degeneration. The permeability of the cartilage matrix was not significantly correlated with age or degeneration. Clinical Relevance: We concluded that the visual or histological appearance of a cartilage specimen may be a poor indicator of its ability to function as the bearing material in the intact joint. A more reliable indicator of the functional properties of a specimen can be obtained either by direct mechanical testing or by biochemical analysis of its composition.

Femoral component loosening using contemporary techniques of femoral cement fixation.

Abstract: A radiographic study was done of 171 total hip replacements that had been followed for an average of 3.3 years (range, two to five years). The study was performed to assess the incidence of loosening of the femoral component in older adult patients (average age, sixty years) in whom the medullary canal had been plugged with methylmethacrylate (using the medullary plug syringe to introduce the plug) prior to introducing the cement (Simplex P) with a cement-gun. Most of the femoral components that were used were of the CAD or HD-2 design, and all were made of chromium-cobalt alloy. Three categories of loosening were defined: definite (requiring radiographic evidence of migration of the component or the cement), probable (requiring evidence of complete 100 per cent radiolucent zone around the cement mantle on one or more radiographs), and possible (requiring evidence of a radiolucent zone that occupied more than 50 but less than 100 per cent of the cement-bone interface on one or more radiographs). One hip required revision for a loose femoral component and another patient had asymptomatic subsidence of the femoral component. Thus, the total incidence of definitely loose femoral components was 1.1 per cent. No hip was classified as having probable loosening; seven hips (4 per cent) were rated as having possible loosening. Compared with the results of four other published reports of patients of similar age with similar follow-up, and using the same radiographic criterion for loosening, the current series demonstrated a statistically significant reduction in the incidence of definitely loose femoral components.

The influence of total knee-replacement design on walking and stair-climbing.

Abstract: The relationship between gait and prosthetic design was studied during level walking and stair-climbing for twenty-six asymptomatic patients after total knee replacement. An age-matched group of fourteen control subjects was also studied. Five designs of total knee replacement Geomedic, Gunston, total condylar, duopatellar, and Cloutier were used. Differences in gait could be identified on the basis of prosthetic design. The more stressful stair-climbing test produced more clearly differentiated function among the different designs. Patients who were treated with the least-constrained cruciate-retaining (Cloutier) design of prosthesis were the only group that had a normal range of motion during climbing up and down stairs. Two groups of patients with semiconstrained (total condylar and Geomedic) designs had a lower than normal range of knee fiexion while descending stairs. Patients with the other designs of prosthesis had a normal range of knee motion on stair-climbing. Kinematic and anatomical differences among the five designs did not have as great an influence on function during level walking as they did during stair-climbing. The results of this study indicate that after total knee replacement even asymptomatic patients with excellent clinical results have an abnormality of gait. The features of the abnormality were common to most of the patients in the series, and consisted of a shorter than normal stride length, reduced mid-stance knee flexion, and abnormal patterns of external flexion-extension moment of the knee. Although an explanation of these abnormalities of gait is not completely possible at this time, they appear to be related to the interaction of the kinematics of the knee and surrounding soft tissues. CLINICAL RELEVANCE: It appears that patients with less constrained cruciate-retaining designs of total knee replacement have a more normal gait during stairclimbing than patients with more constrained cruciate-sacrificing designs. During level walking, patients with five quite different designs all had abnormalities of gait in spite of a successful clinical result. There is currently a great deal of controversy regarding which type of total knee prosthesis provides better Funded in part by National Institutes of Health Grants KO4AMO()493 and ROIAM2O7O2 and by the Arthritis Foundation. 1 Department of Orthopedic Surgery . Rush-Presbyterian-St. Luke’s N’lcdical Center. 753 Wcst Congress Parkway, Chicago. Illinois 60612. gait. An improved understanding of gait and the variables associated with total knee designs is essential in addressing this controversy. Quantitative studies of gait during activities of daily living are needed to generate this information, and will be useful for the evaluation of total kneereplacement devices and for providing understanding of the loading patterns that may occur during normal activity. Several studies have evaluated gait in patients with knee disease. These investigations included kinematic analyses I .6.7.9.I i.2I , time-distance measurements, and force-plate measurements. There have also been several kinetic and force-analysis studies of function in normal subjects and in patients after treatment for knee disabilitiesaIa14l7ao. The common finding of these studies was that patients who appear to be clinically asymptomatic after joint replacement have abnormal gait patterns. Currently, little is known about the nature of the gait abnormality in patients after total knee replacement or its relationship to total knee-replacement design. The purpose of this study was to evaluate the relationship between gait and total knee-replacement design. The prosthetic knees that were selected for this study were considered to be representative of cruciate-sacrificing and sparing designs with varying amounts of constraint. The parameters ofgait that we observed included time-distance patterns and motion and moments of the knee joint. The gait of patients who had received one of five different designs of total knee replacement was evaluated and cornpared with that of control subjects. Materials and Methods Twenty-six patients. in five experimental groups. were studied during level walking and stair-climbing. Patients were grouped according to which of five total knee designs they had received. The five implants selected for this study were the Geomedic, Gunston, total condylar. duopatellar, and Cloutier designs. The five designs of prosthesis were selected to represent varying shapes of the articular surfaces and the retention of one, both, or neither cruciate ligament. The Geomedic prosthesis has fairly congruous articular surfaces. requires removal of the anterior cruciate ligament, permits retention of the ps)sterior cruciate ligament. and does not include a patellar flange or resurfacing. The Gunston prosthesis consists of two separate semicircular runners that articulate with two independent tibial components, permits retention of both cruciate ligaments. and does not include patellar resurfacing or a patellar flange. The total condylar design requires the sacrifice of both cruciate ligaments. with anterior-posterior stability provided by the conformity of the tibial articulating surfaces; all patients with this design had patellar resurfacing. The duopatellar prosthesis permits retention of the posterior cruciate ligament. includes a patellar flange. and allows patellar resurfacing, which was performed in all of the patients whom we examined. The Cloutier prosthesis allows retention of both cruciate ligaments and the femoral condyles are asymmetneal, diverge. and have varying radii of curvature. The tibial component of the Cloutier device consists of flat articular surfaces supported on a metal retainer, and the design has a patellar flange. but patellar resurfacing was not performed in our patients. The patients selected for this study were matched according to postoperative pain. function, passive range of motion, and joint stability. A point system based on The Hospital for Special Surgery knee.rating system was used to quantitate

A ten-year follow-up of one hundred consecutive Müller curved-stem total hip-replacement arthroplasties.

Abstract: One hundred consecutive Muller curved-stem total hip replacements were reviewed ten years after operation. Twenty patients with twenty-two arthroplasties had died within the ten-year period without having a revision, and twenty-five arthroplasties had been revised for various reasons. Of the remaining fifty-three arthroplasties, thirty-five were classified as good or excellent, with Harris hip scores of 80 points or higher, and eighteen were classified as poor or fair, with scores lower than 80 points. Follow-up radiographs, made for all but six of the fifty-three hips at ten years, showed a 23 per cent incidence of migration of the acetabular component and a 28 per cent incidence of migration of the femoral component. In addition, there was a 15 per cent incidence of bone resorption in the proximal end of the femur without migration of the femoral component and a 4 per cent incidence of osteolytic defects about the femoral component, also without migration. Combining the radiographically loose replacement (migration) with the clinically loose ones (revised), the over-all incidence of aseptic loosening was 29 per cent for the acetabular component and 40 per cent for the femoral component. There was a positive correlation between the incidence of loosening of the femoral component and younger age, heavier weight, male sex, unilateral hip disease, a wide femoral canal, and varus position of the femoral component, whereas the incidence of loosening of the acetabular component was increased only in association with older age. The rate of loosening of the femoral component appeared to be higher during the early follow-up period and to decrease with time, while the rate of loosening of the acetabular component appeared to be lower during the early follow-up period but to increase with time.

The hazards of biopsy in patients with malignant primary bone and soft-tissue tumors.

Abstract: This study was performed by the Musculoskeletal Tumour Society using questionnaires to assess the following: • The accuracy of biopsy in making a diagnosis • The incidence of complications associated with the biopsy procedure • The effects of errors in diagnosis and of complications on the treatment of patients • Whether these problems occurred with greater frequency when the initial biopsy was performed in a referring institution or in a specialist treating centre Each member of the Society submitted data on 20 sequential, unselected, newly diagnosed patients with malignant primary tumours of bone or soft tissue who underwent a biopsy and then a defi nitive procedure. The study received data from 20 orthopedic surgeons in 16 treating centres. Information on 329 patients included a wide range of diagnoses (but generally conforming to the distribution of these tumours in the general population). The mean age of the patients was 36.5 years (range, 2 weeks to 83 years). Two hundred and twenty two lesions were bone primaries and 107 were derived from soft tissue. One hundred and forty three tumours were biopsied in the referring institution and 171 in the treating centre. The authors demonstrated 60 (18.2 %) major errors in diagnosis and 34 (10.3 %) non-representative or technically poor biopsies. Fifty-seven patients (17.3 %) encountered problems in the skin, soft tissue, or bone following biopsy and the optimum treatment plan had to be altered as a result of problems related to the biopsy in 60 patients (18.2 %). In 15 patients (4.5 %) an unnecessary amputation was performed as a result of problems with the biopsy, and in 28 patients (8.5 %) the prognosis and outcome were considered to have been adversely affected. Patients undergoing a biopsy at the referring institution experienced biopsy-related problems three to fi ve times more frequently than those undergoing biopsy at a treating centre. Given these fi ndings, the authors recommend that the biopsy should be planned as carefully as defi nitive surgery. In particular, careful attention should be paid to the following: • Asepsis, skin-handling, haemostasis, and wound closure • Precise skin incision placement, which will not compromise subsequent surgery. • The tissue obtained should be suffi cient in volume and suffi ciently representative of the lesion that the pathologist can provide a defi nitive diagnosis. If the surgeon or the institution is not prepared to perform accurate diagnostic studies or proceed with defi nitive treatment for these patients, patients should be referred to a treating centre prior to biopsy. The Hazards of Biopsy in Patients with Malignant Primary Bone and SoftTissue Tumors

Ten-year follow-up study of total hip replacement.

Abstract: Of the first 300 consecutive patients who had a Charnley total hip replacement at the Mayo Clinic during the years 1960 to 1970, 207 (231 hips) were re-evaluated ten years postoperative by questionnaire and roentgenograms. Forty-three of these were also evaluated by personal examination. Roentgenographic loosening of the acetabular component was determined using the criterion of a complete radiolucent line more than one millimeter in width at the bone-cement interface or any migration or tilting of the component. For the femoral component, the criterion for loosening was a radiolucent line more than one millimeter wide at either the bone-cement or the cement-prosthesis interface, or any change in the position of the component. As previously reported, the incidence of loose components at five years was 6.5 per cent for the acetabular component and 24 per cent for the femoral component. At ten years the incidence of loosening had increased to 11.3 per cent for the acetabular component and 29.9 per cent for the femoral component. Therefore, between five and ten years postoperatively the rate of femoral loosening decreased, while the rate of acetabular loosening remained about the same. The overall-revision rate for loosening of total hip components increased from 3 per cent at five years to 7.4 per cent at ten years. Acetabular wear was not a significant problem. Resorption of the medial femoral cortex near the calcar was generally non-progressive and was not significantly related to loosening. two modes of loosening are suggested, the more common being cracking of the cement mantle due to circumferential (hoop) stresses within the cement. This series probably represents a so-called worst-case experience, since changes in design and materials as well as the improvements in surgical technique that have evolved over the past decade should provide significantly better long-term fixation.

Anterior cruciate ligament reconstruction using one-third of the patellar ligament, augmented by extra-articular tendon transfers.

Abstract: Eighty patients with persistent clinical and functional instability of the knee due to anterior cruciate ligament insufficiency underwent the operation reported, in which one-third of the patellar ligament substitutes for the cruciate ligament and extraarticular tendon transfers, medial and lateral, augment the substitution. The patients were followed for a minimum of two years, and fifty returned for personal evaluation. The average follow-up was thirty-three months, with a range of two to five years. There were thirty-five male and fifteen female patients. The average age was twenty-three years. The average interval from initial injury to the index operation was two years. Meniscal tears and articular changes were noted in most of the patients. Forty-three (86 per cent) of the fifty patients had at least one torn meniscus, twenty-seven patients (54 per cent) had significant degenerative articular changes, and fourteen (28 per cent) had patellar articular changes. In the procedure described, eccentric placement of the tibial and femoral tunnels for more accurate placement of the patellar ligament substitute is essential. The over-all results were graded as excellent in thirty knees, good in seventeen, fair in one, and a failure in two. One knee that was classified as a failure showed excellent stability, but the patient had significant pain from chondromalacia of the patella, while significant pain and hyperesthesia from a neuroma was the reason for failure in the second patient.

An in vitro biomechanical evaluation of anterior-posterior motion of the knee. Tibial displacement, rotation, and torque.

Abstract: We tested the anterior-posterior motion of nine normal cadaver knees in zero to 90 degrees of flexion using a specially designed apparatus. This apparatus applied a dynamic anterior-posterior force to each knee and measured the resulting tibial displacement, rotation, and torque. In the intact knee, an anterior force produced an internal tibial torque and internal tibial rotation, while a posterior force produced an external torque and external rotation. Anterior-posterior displacement increased by 30 per cent when the tibia was allowed to rotate freely about its neutral rotation position. Isolated section of the anterior cruciate ligament produced more than double the amount of anterior displacement without affecting posterior displacement. Isolated section of the posterior cruciate ligament produced almost triple the amount of posterior displacement without affecting anterior displacement. After cutting either the anterior or the posterior cruciate ligament, the resulting internal or external secondary tibial rotation disappeared. It appears, therefore, that the anterior and posterior cruciate ligaments are the primary restraints to motion in the anterior and posterior directions as well as the causes of internal and external tibial rotation during anterior and posterior motion.

Anterior cruciate ligament replacement using patellar tendon. An evaluation of graft revascularization in the dog.

Abstract: We investigated the revascularization pattern of patellar tendon grafts used to replace the anterior cruciate ligament in thirty-six dogs by histological and tissue-clearing (Spalteholz) techniques. Initially the grafts were avascular, but by six weeks they were completely ensheathed in a vascular synovial envelope. The soft tissues of the infrapatellar fat pad, the tibial remnant of the anterior cruciate ligament, and the posterior synovial tissues contributed to this synovial vasculature. Intrinsic revascularization of the patellar tendon graft progressed from the proximal and distal portions of the graft centrally and was complete by twenty weeks. The tibial attachment of the patellar tendon graft did not contribute any vessels to the revascularization process. At one year, the vascular and histological appearance of the patellar tendon graft resembled that of a normal anterior cruciate ligament. Clinical Relevance: The absence of perfused vessels within the patellar tendon graft immediately after transplantation within the knee joint and the failure of the osseous insertion of the graft to contribute vessels to the revascularization process suggest that although it is left attached at the tibia, the patellar tendon graft is essentially an avascular free graft at transplantation. The contribution of the soft tissues of the knee to the revascularization process of the graft suggests preservation and utilization of the infrapatellar fat pad and synovial tissue to optimize the graft's revascularization and ultimate viability.

Loads on the lumbar spine. Validation of a biomechanical analysis by measurements of intradiscal pressures and myoelectric signals.

Abstract: We studied the validity of predictions of compressive loads on the lumbar spine and contraction forces in lumbar trunk muscles based on a biomechanical model. The predictions were validated by quantitative measurements of myoelectric activities at twelve locations on the trunk and of the pressure in the third lumbar disc. Twenty-five tasks were performed isometrically by four healthy volunteers. The model predicted that the tasks imposed mean compressive loads on the spine of as much as 2400 newtons and required contraction forces of the posterior muscles of the back of as much as 1800 newtons. Intradiscal pressures of as much as 1600 kilopascals were measured. The predicted and measured quantities were well correlated. It appears that the model adequately predicted the compressive loads on the lumbar spine and the tensions in the back muscles. Clinical Relevance: Patients with low-back disorders limit their physical activities, which indicates that loading on the spine must be a factor in those disorders. This study shows that the loads imposed on the spine by physical activities need not be measured. They can easily be calculated. This will significantly accelerate biomechanics research on low-back disorders. The calculation techniques that we validated for predicting loads on the spine can be used to calculate the loads on any skeletal structure. Those loads are largely determined not by the externally applied loads, but by the moments of those applied loads and by the moments of the weights of the body segments that the structure must support.

The structure of the posterolateral aspect of the knee.

Abstract: The lateral structures of the knee can be divided into three distinct layers. The deepest layer, the lateral part of the capsule, divides into two laminae just posterior to the overlying iliotibial tract. These laminae encompass three ligaments: the lateral collateral, the fabellofibular, and the arcuate ligaments. Three major anatomical variations are seen: reinforcement of the capsule by the arcuate ligament alone (13 per cent), by the fabellofibular ligament alone (20 per cent), and by both ligaments (67 per cent). One can predict which variation will be seen in a given patient from the information provided by a radiograph and by physical examination.

Giant-cell tumor of bone: analysis of two hundred and eight cases in chinese patients

Abstract: Giant-cell tumor of bone seems to occur more frequently in Chinese people than in those residing in Western countries. The estimated incidence is about 20 per cent of all primary tumors of bone. Of 208 surgically treated and pathologically proved giant-cell tumors, 194 were benign. We excluded patients with primary or secondary amputation unrelated to recurrence and those followed for less than two years or lost to follow-up. Of the remaining 111 patients who were followed for more than two years, twenty-nine had a recurrence, giving a recurrence rate of 26.1 per cent. The rate of recurrence was highest following curettage and bone-grafting (41.2 per cent) and was much lower in patients who were treated by resection and fusion (7.1 per cent). Since resection of this tumor with reconstructive procedures, either by massive homogenous bone-grafting or artificial joint replacement, is complicated and might cripple the patient if it fails, we propose excision and curettage with bone-grafting as the most suitable method of treatment in the majority of patients with giant-cell tumor of bone.

Correction of post-traumatic wrist deformity in adults by osteotomy, bone-grafting, and internal fixation.

Abstract: A corrective osteotomy for post-traumatic malalignment of the distal end of the radius was performed in twenty patients who were followed for an average of 3.6 years. The indications for correction were based on age, degree of deformity, limitation of function, pain, and appearance of the wrist. The procedure included an opening-wedge metaphyseal osteotomy combined with insertion of a graft and rigid internal fixation with a plate and screws to permit early motion. Depending on the direction of the angulation, a dorsal or volar approach was employed to guarantee a buttressing effect of the plate. The procedure gave satisfactory results when there were no degenerative changes in the radiocarpal or intercarpal joints and when the preoperative range of motion of the wrist was adequate. The results were graded as excellent in five patients, good in ten, fair in four, and poor in one.

Chronic unreduced dislocations of the shoulder.

Abstract: We evaluated the results of treatment in twenty-three patients with twenty-four shoulder dislocations that had gone unreduced for at least three weeks. Fourteen dislocations were posterior, eight were anterior, and one each was superior and inferior. Seventy-nine per cent of the posterior dislocations had not been recognized by the initial treating physician. Fourteen shoulders (58 per cent) were operated on. Of seven that were treated by open reduction with preservation of the humeral head, the results in two were graded as excellent; in three, as good; and in two, as fair. A Neer total shoulder-replacement prosthesis was used in one patient with an excellent result, and a Neer humeral-head prosthesis was used in two patients with a good and a fair result. In four patients, the humeral head was removed and a Jones procedure was performed, with one good and three fair results. There were no poor results after surgical treatment and it was not necessary to arthrodese any shoulder. We did not find it necessary to transfix the shoulder joint by screws or pins, or to use plaster spica casts to maintain stability of the shoulder following open reduction. Supporting the arm at the side in a position posterior to the coronal plane for a posterior dislocation, and anterior to the coronal plane for an anterior dislocation, proved to be comfortable and effective. There were no postoperative dislocations using this simple method. These results show that the over-all prognosis for surgical treatment of the chronic unreduced dislocation shoulder is more favorable than has previously been reported. A rating system based on 100 units was used to evaluate our final results, and is recommended as a standard system for future comparative studies.

Anterior stabilization for acute fractures and non-unions of the dens.

Abstract: The dens can be reached and directly stabilized from an anterior cervical approach, provided that x-ray image intensification is employed. Through this approach, twelve delayed unions and non-unions of the dens were treated with a bone graft impacted into a trough in the body of the second cervical vertebra and into a canal in the dens, together with a concomitant posterior arthrodesis. Fifteen additional fractures of the dens were stabilized with compression screws, introduced from the anteroinferior margin of the second cervical vertebra into the dens. Four of these fractures had delayed union, and an anterior onlay bone graft was added to the screw fixation. All of the delayed unions, non-unions, and acute fractures healed with bone union and without major complications. The acute fractures showed bone union in six to eight weeks after anterior fixation with compression screws alone. Delayed unions were found to need an anterior onlay bone graft in addition to the screw fixation. Established non-unions should be stabilized with a posterior arthrodesis of the first to the second cervical vertebra and inlay grafting of the non union itself to ensure both anterior and posterior healing.

Infection rates after 3175 total hip and total knee replacements performed with and without a horizontal unidirectional filtered air-flow system.

Abstract: To determine the effect of the ventilation system on infection rates after total hip and total knee arthroplasties performed in operating rooms with and without a horizontal unidirectional filtered air-flow system, using modern antiseptic conditions and antibiotic prophylaxis, all of the single-stage procedures (3175 of a total of 4769) were subjected to statistical analysis and fifty-seven matched pairs for controls were established. A reduced infection rate after total hip replacement (from 1.4 to 0.9 per cent) and an increased infection rate after total knee replacement (from 1.4 to 3.9 per cent) were found when patients operated on in the filtered laminar air-flow operating room were compared with those whose operations were done in two conventional rooms. This pattern was statistically significant and was believed to be due to the positions of the operating team and of the wound with respect to the air flow. Prospectively accumulated factors (such as the experience of the surgeon, the duration of surgery, the diagnosis, and the patient's age) as well as retrospectively accumulated factors (such as predisposing conditions of the patient) did not explain the observed patterns of infection.

Performance of the tibial component in total knee replacement.

Abstract: In patients with deficient bone in the proximal end of the tibia, the mechanical support of a conventional total knee replacement may be inadequate. We have developed a custom design for use in situations in which there is extensive deficiency of tibial cancellous bone. To do this, we examined conventional and custom prosthetic tibial components using finite-element analysis. Several loading configurations were tested, and the worst loading conditions were found to be those in which eccentric loads were placed on the margin of the tibial component. The results showed that the stresses on the cancellous bone beneath a conventional-design prosthesis may be lowered if a metal tray and metal peg are employed. A salvage-design concept for revision in the presence of deficient cancellous bone was tested analytically and used successfully. This concept requires that some portion of the applied load be transferred directly to the tibial cortical shell. Stresses in the remaining cancellous bone were lowered by the combination of a thickened metal tray and a metal support buttress. Clinical Relevance: This study demonstrates the advantage of metal trays for the tibial plateau and suggests that they should be used whenever the supporting tibial bone is insufficient. In knees in which there are large defects in the bone, direct transfer of the load to the cortical shell through the prosthesis, made possible by a custom design, appears to be necessary.

Nutrition in orthopaedic surgery.

Abstract: One hundred and twenty-nine patients undergoing orthopaedic surgical procedures were found to have an average incidence of clinical and subclinical malnutrition of 42.4 per cent per patient. The lowest incidence of nutritional depletion was identified in patients undergoing total hip-replacement surgery (28.6 per cent), followed by the elective surgical group (35.3 per cent) and patients with multiple trauma and femoral fractures (58.6 per cent). Trauma and major surgery were shown to induce a state of malnutrition and a loss of immunocompetence. A significant (p less than 0.05) correlation between subnormal nutritional indices and the development of complications was identified. A comprehensive approach to the detection and correction of malnutrition in orthopaedic patients is described.

The effect on supination-pronation of angular malalignment of fractures of both bones of the forearm.

Abstract: Ten fresh human upper-extremity cadaver specimens were tested for the effect of residual angulation from simulated fractures of both bones of the forearm on the potential for range of rotation of the forearm and for limitations of pronation and supination specifically. Ten and 20-degree angulations for the radius and ulna, such as might be encountered in all reasonable clinical situations, were tested. Little significant loss of forearm rotation resulted from angulations of 10 degrees in any direction. With 20 degrees of angulation, there was statistically significant and functionally important loss of forearm rotation. Clinical Relevance: A residual angulation of 10 degrees in mid-shaft fractures of the radius, ulna, or both bones of the forearm will not limit forearm rotation anatomically. Loss in the range of rotation can be expected with residual angeles of 20 degrees or more.

The discoid lateral-meniscus syndrome

Abstract: Discoid lateral meniscus has been described as a morphologically variable anomaly, and several classifications have been proposed. We have seen twelve patients with the so-called complete type of discoid lateral meniscus, with intact ligament attachments as an incidental finding at the time of arthroscopy. Ten of the twelve patients were without significant symptoms attributable to the meniscus; that is, they had no meniscal tears or laxity. We also have seen six patients with the Wrisberg-ligament type of discoid lateral meniscus, in which there is abnormal meniscal mobility. All six patients were symptomatic and had the so-called snapping-knee syndrome, for which they had arthroscopic lateral meniscectomy. During arthroscopy, care should be taken not to confuse the asymptomatic complete type of discoid lateral meniscus with the Wrisberg-ligament type.

Synovial and osseous inflammation in failed silicone-rubber prostheses.

Abstract: A foreign-body giant-cell synovitis together with foci of foreign-body giant cells and chronic inflammation in the intramedullary bone was present in six patients with failed silicone-rubber prostheses. Scanning electron microscopy of a removed siliconerubber implant showed particulate debris on the surface which was similar morphologically to the intracellular material that was seen in the synovial giant cells. Since the early 1960’s, silicone polymers (see Appendix) have had an increasing popularity as materials for the manufacture of implants in the fields of orthopaedic, plastic, neural, and cardiac surgery5 ’6’21. It has been reported that prostheses manufactured from these substances are generally long-lasting, provoking only a very mild inflammatory response in the tissues in which they are embedded 10.13 Swanson found silicone rubber to be particularly suitable for use in metacarpal-carpal and interphalangeal-joint prostheses 21.22#{149} Since the introduction of these prostheses in the late 1960’s, thousands ofjoints that had been destroyed by trauma or arthritis have been replaced with Swanson implants. These implants have been reported to be long-lived and stable, and to have a low rate of complications lt.21.22#{149} However, it is now well recognized in the field of plastic surgery that after the use of various types of silicone-polymer prostheses, severe inflammatory reactions to the implanted materials may be observed 2.13.20.23 In this paper, we are reporting on a series of six patients with reactive synovitis and foreign-body giant-cell reaction to particulate silicone rubber as well as on the first reported cases of foreign-body giant-cell reaction to silicone rubber in intramedullary bone. The patients had been treated with silicone-rubber prostheses of the metacarpophalangeal joint , trapezium , trapezoid , wrist, elbow , and great toe. Material and Methods Table I is a summary of the clinical features of the six patients whom we studied and reported on. All six patients were white. There were two men, thirty-seven and fortynine years old, and four women, ranging in age from thirty-five to sixty-six. The diagnoses that prompted the S Pathology Department, The Hospital for Special Surgery, 535 East 70th Street, New York, N.Y. 10021. initial operation were post-traumatic arthritis in two patients, primary degenerative joint disease in one, subluxation in one, seronegative rheumatoid arthritis in one, and polyarticular rheumatoid arthritis in one. One patient had a radial head prosthesis; one, a metatarosophalangeal prosthesis; two, trapezium implants; one, multiple hand and wrist prostheses; and one patient had a trapezoid implant inserted bilaterally. In all of the patients the implants had been in place for at least one year. The removed radialhead prosthesis was available for study. The patients’ complaints at the time of removal or revision of the im‘ ‘ t& # ‘1$ ; ?A: Cr . :4: -. . -... ‘: . : , dh1li0 . .#_ .-. -. -: .mrft-.a .-.-.. -. . --: I tV ,, ,.ti;e;. i I ‘ . ..‘ ,. ‘-. ,‘ . I r . :. 5. 4) ’$’ C ; , e -.#{231} ; . . . ; : . . .. ,:. , . ; . . .: ....;...... .. ,.:‘. . . . . . 5 .-__ . ... -. .. : _ .: . , : . :; .L.. . . --4 ,. _ j-... ..... . .. -... -. . .‘ . . ‘ :.r . .-I.) ) I ;-. : .. . . ---:: ,-4.;.. : s. --‘-:‘ -d . . :. . -