Outbreak of surgical wound infections associated with total hip arthroplasty.

OBJECTIVES: Describe an outbreak of surgical wound infections associated with total hip arthroplasty; identify risk factors for surgical wound infection during the pre-outbreak and outbreak periods. SETTING: A 100-bed hospital. From May 1 to September 30, 1988, 7 of 15 patients who underwent total hip arthroplasty developed surgical wound infections from Staphylococcus aureus (5), Enterobacter cloacae (1), beta-hemolytic streptococci (1), enterococci (1), coagulase-negative staphylococci (1), and Escherichia coli (1) (attack rate = 46.7%). DESIGN: Retrospective cohort studies comparing surgical wound infection rates by patient- and procedure-related risk factors during the pre-outbreak and outbreak periods were conducted. Drop plate quantitative air culturing was conducted in 10 consecutive total hip arthroplasties in the subsequent 6 months. RESULTS: Rates of surgical wound infection were surgically higher for arthroplasties in which no intraoperative prophylactic antimicrobials were given (44% versus 8%, relative risk [RR] = 5.4, p = .01), or in which the posterior approach (20% versus 3%, RR = 6.7, p = .04) or a specific prosthesis (39% versus 5%, RR = 6.3, p = 0.01) was used. The surgical wound infection rate was highest when one circulating nurse, Nurse A, assisted (47% versus 4%, RR = 12.8, p less than .001). Logistic regression analysis identified use of the posterior approach (RR = 1.8, p = .04) and Nurse A's participation (RR = 5.0, p less than .001) as independent risk factors for surgical wound infection. Interviews of the nursing supervisor indicated that Nurse A had recurrent dermatitis on her hands. During 6 months following Nurse A's reassignment, the rate declined significantly (from 7/15 to 0/10, p = .01). Drop plate culturing yielded 2 to 10 colonies per plate of organisms that did not match outbreak organisms. CONCLUSIONS: Outbreaks associated with personnel generally involve only 1 species. In this outbreak, Nurse A (possibly because of her dermatitis), technique, the posterior approach, and/or other undetermined factors were the primary predictors of surgical wound infection.

Arthroplasty of the hip and knee in juvenile rheumatoid arthritis.

The primary reason for total hip and total knee replacement in patients with juvenile rheumatoid arthritis is marked functional impairment. Secondary reasons are severe disabling pain and deformity. By the time a patient is ready for arthroplasty, alternatives to surgery have already been considered; synovectomies, soft-tissue releases, and osteotomies have already been performed, or the destructive process is too advanced for any form of therapy to have a considerable effect.

Effect of preoperative autologous blood donation and intraoperative and postoperative blood recovery on homologous blood transfusion requirement in cementless total hip replacement operation.

BACKGROUND: Blood transfusion is often necessary in operations for total hip replacement (THR). This study was done to investigate the efficacy of three different methods of autologous blood conservation and transfusion in patients undergoing primary THR without cement. STUDY DESIGN: One hundred fifty-five patients with osteoarthritis underwent unilateral cementless THR using normotensive general anesthesia performed by a single surgeon. The patients were divided into four groups depending on which conservation method was used. Ten different demographic and hematologic parameters were recorded and analyzed by using analysis of the variance and multiple regression methods. RESULTS: All three methods were effective in reducing the need for homologous blood transfusions. The greatest benefit was realized when both preoperative autologous blood donation and intraoperative salvage using the Cell Saver were combined. The addition of postoperative salvage and retransfusion of wound drainage blood using the Solcotrans System did not significantly reduce further the chance of homologous blood transfusions. CONCLUSIONS: The data from this study were similar to previously published reports. Regression analysis confirmed the correlation among the different variables studied. We currently offer preoperative donation and intraoperative salvage with the Cell Saver to patients undergoing cementless total hip replacement.

Effects of ingrowth, geometry, and material on stress transfer under porous-coated hip surface replacements.

Three different interface geometries for porous ingrowth surface replacements of the hip were examined using two-dimensional linear and nonlinear contact finite element analyses. The results indicate that incorporation of a nearly flat prosthesis interface between the surface replacement and the underlying cancellous bone may reduce stress shielding and improve stress transfer from the component. For all designs analyzed, the bone stress shielding was insensitive to component material stiffness when the elastic modulus was greater than 30 MPa. The use of titanium instead of cobalt-chrome (Co--Cr) as the prosthesis material therefore had a negligible effect on stress shielding.

Changes in tibial bone mass after primary cementless and revision cementless total hip arthroplasty in canine models.

The purpose of this study was to examine right-left differences in tibial bone mass after unilateral (left) cementless total hip arthroplasty (THA). Of 39 dogs with THAs, 9 had primary cementless porous-coated femoral stems for 6 months and 15 had similar stems for 2 years. Five dogs had aseptically failed cemented hips, and 10 had aseptically failed cemented hips that were revised with cementless porous-coated femoral stems (5 without bone graft and 5 with autogenous bone graft). These animals were sacrificed 6 months after the revision surgery. The primary cementless dogs showed no right-left difference in tibial bone mineral content (BMC) or cortical bone cross-sectional geometry after 6 months, but after 2 years there was a distal right-left difference in BMC of 6% caused by expansion of the medullary canal in the tibia of the operated limb. Tibial BMC was more than 20% lower in the operated limb of the failed cemented dogs, approximately 15% lower in the nongrafted group, and 7% lower in the grafted group. The right-left tibial difference in BMC in the 2-year primary cementless group is most probably because of subclinical disuse of the operated limb. Among the dogs with failed cemented stems, the lower right-left difference in the two revised groups compared with the non-revised group suggests that improved limb function after cementless revision THA may cause gain of previously lost bone.

Comparison of healing of allograft/endoprosthetic composites with three types of gluteus medius attachment.

This study compared three methods of gluteus medius tendon attachment to an allograft/endoprosthetic composite of the proximal 25% of the femur in a canine model. The three methods were bone to bone, tendon to bone, and tendon to tendon attachment. In an in vivo study, 24 dogs were assigned to three groups of eight dogs each, and serial radiography and weight-bearing analyses were performed throughout the study. The dogs were killed at 6 months, and the specimens were tested in tension to failure and were analyzed histologically. In an in vitro study, each repair was done on six limbs, with a contralateral limb serving as a control for each. In these specimens, the bone to bone attachments were significantly stronger (99.1% of the controls) than the tendon to bone attachments (71.8% of the controls) and the tendon to tendon attachments (40.0% of the controls); there were no differences in tensile stiffness among the three types of attachment. By 6 months, the tensile strength of the tendon to tendon attachments increased significantly and that of the tendon to bone attachments decreased significantly. There were no significant differences in tensile strength among the three types of attachment. The tensile stiffness of the bone to bone attachments (91.0% of the controls) was significantly greater than that of the tendon to bone attachments (40.8% of the controls) but not significantly different from that of the tendon to tendon attachments (63.2% of the controls). The bone to bone attachment was associated with increased bone resorption, bone remodeling, and bone porosity, accompanied by thinner allograft cortices, when compared with the other types of attachment. In dogs with a bone to bone attachment, weight-bearing increased more slowly than in dogs with either of the other two attachments. These changes associated with the bone to bone attachment may merely be secondary to healing of the bone to bone attachment to the greater trochanter; therefore, they may only be temporary phenomena or they may be the portents for long-term complications. Longer term studies of at least 1-2 years must be performed before these questions can be answered.

Ten strategies to reduce blood loss in orthopedic surgery.

In any operative procedure, careful surgical dissection with precise hemostasis is one of the most effective ways to minimize surgical blood loss and reduce the need for allogeneic red blood cell transfusion. Several other techniques contribute to reduce blood loss in major orthopedic procedures. These techniques are reviewed and include rehearsal of the procedure and positioning the patient to reduce venous engorgement. In addition, a case report is presented that demonstrates the feasibility of revision hip replacement surgery without the use of transfusion in a Jehovah's Witness patient.

The bone-implant interface of femoral stems with non-circumferential porous coating.

UNLABELLED: A histological study was performed of the bone-implant interface of fifteen titanium-alloy femoral stems with porous coating limited to three proximal areas that did not cover the full circumference of the device. The specimens were obtained at autopsy from ten cadavera at a mean of forty-six months (range, one to eighty-nine months) after the implant had been inserted without acrylic cement. The volume fraction of bone within the porous spaces (the percentage of the porous space that was filled with bone) and the extent of bone ingrowth (the percentage of the porous-coated surface covered with in-grown bone that was more than one-half fiber-diameter deep, as measured from the outer surface of the porous coating), were determined with histomorphometric methods. Eleven of the fifteen stems had bone within the porous coating that was in continuity with the surrounding medullary bone. The mean volume fraction of bone ingrowth in these specimens was 26.9 per cent (range, 12.2 to 61.0 per cent), and the mean extent of bone ingrowth was 64.3 per cent (range, 28.6 to 95.2 per cent). Both of these parameters increased with time. In the other four stems, the bone lacked continuity with the surrounding trabecular bed. Two of these stems had a limited amount of bone within the porous coating, and two stems (from one patient) had no bone ingrowth. Periprosthetic membranes surrounded by a shell of trabecular bone covered the uncoated surfaces of the stems. The membranes of implants that had been in situ for eight months or more demonstrated polyethylene wear debris, and other particles generated at the level of the joint, within histiocytes throughout the length of the femoral stem. CLINICAL RELEVANCE: The findings in this study are relevant to the utilization and mechanisms of failure of femoral stems inserted without cement. Bone ingrowth and the resulting stability of the implant can be achieved with porous-coated stems. However, the extent of the surface that is porous-coated must be sufficient to prevent trabecular fracture as a secondary mechanism of loosening. Interruptions in the circumferential extent of the porous surface are associated with the formation of periprosthetic membranes, which provide a pathway for migration of particulate wear and corrosion products to the distal part of the stem. A circumferential coating may retard the access of particles and thus decrease the possibility of diaphyseal osteolysis.

Surface replacement of the hip with the Tharies system. Two to five-year results.

The two to five-year clinical results of 200 Tharies surface replacements were comparable to those of conventional total hip replacement. The incidence of systemic complications, dislocations, and sepsis was low. There were ten cases of aseptic and one case of septic loosening. Nine minor secondary procedures were required in the series. In two patients the femoral component shifted asymptomatically into varus angulation, but no revision was needed. Fifty-five per cent of patients for whom serial radiographs were available had some progression of radiolucency, but there was poor correlation between the width of the zone and loosening until the patient became symptomatic. Improved techniques of preparation of the interface and of delivery, compression, and containment of the cement have improved the postoperative radiographic appearance of the more recently treated patients.

Micromotion of femoral stems in total hip arthroplasty. A randomized study of cemented, hydroxyapatite-coated, and porous-coated stems with roentgen stereophotogrammetric analysis.

The fixation of the femoral stem in a total hip arthroplasty was studied in sixty patients (sixty-four hips) with use of roentgen stereophotogrammetric analysis. The hips were randomly stratified on the basis of the age, sex, and weight of the patient; the roentgenographic quality of the bone; and the reason for the operation (primary or secondary osteoarthrosis). The hips were then randomly assigned to one of three types of fixation of the femoral component: insertion with cement, hydroxyapatite coating, or porous coating. Examinations with roentgen stereophotogrammetry were done as long as two years after the operation. Micromotion of the prostheses was evaluated in terms of subsidence or proximal migration and rotations and translations of the proximal-lateral (shoulder) and distal (tip) parts of the prostheses. The clinical results at the two-year follow-up evaluation did not differ significantly between the groups with regard to the Harris hip score or the pain score (p > 0.05 for both; Wilcoxon rank-sum test). There were small or no differences in rotations and micromotions of the shoulder and the tip of the prostheses. Increased subsidence of 0.1 to 0.2 millimeter was recorded for the cemented and the porous-coated prostheses (p = 0.002 and p = 0.02, respectively; Wilcoxon rank-sum test). Thus, proximal hydroxyapatite coating seems to enhance the early fixation of the stem. Conventional roentgenography revealed an increased number of radiodense lines surrounding the porous-coated prostheses. Distal hypertrophy of the femoral cortex was found mainly around the hydroxyapatite-coated prostheses. Proximal resorption of bone and heterotopic ossification occurred to approximately the same extent regardless of the type of fixation used.

The prevalence of femoral osteolysis associated with components inserted with or without cement in total hip replacements. A retrospective matched-pair series.

The prevalence of femoral osteolysis in hips in which a femoral component had been inserted without cement was compared with that in hips with a cemented component, in a retrospective matched-pair study of the results of primary total hip arthroplasties; all patients had received the same type of acetabular component. Forty-one hips in thirty-nine patients who had a Harris-Galante porous-coated total hip prosthesis without cement were matched by age, sex, weight, duration of follow-up, and diagnosis with forty-one hips in thirty-eight patients who had a hybrid total hip reconstruction; the hybrid reconstruction consisted of the same acetabular component and a Precoat femoral component inserted with a so-called third-generation cementing technique. All of the operations were done by the same surgeon, who used the same operative approach and the same course of postoperative rehabilitation. All of the patients were followed for at least four years (mean, six years). Osteolysis developed in twelve (29 percent) of the hips that had a femoral component without cement compared with none of the hips that had a cemented component (p < 0.0002). At the latest follow-up examination, none of the femoral components that had been inserted with cement were loose and none had been revised, while eight (20 percent) of the femoral components that had been inserted without cement were loose and five (12 per cent) had been revised. This retrospective matched-pair study controlled for many of the variables associated with a comparison of the rates of femoral osteolysis in separate series of femoral components fixed with and without cement.(ABSTRACT TRUNCATED AT 250 WORDS)

The femoral component in total hip arthroplasty. Six to eight-year follow-up of one hundred consecutive patients after use of a third-generation cementing technique.

One hundred consecutive patients had a primary unilateral total hip arthroplasty with use of a single design of the femoral component (Harris Precoat), inserted with a so-called third-generation cementing technique, between July 1985 and June 1987. There were seventy-four women and twenty-six men. The mean age at the time of the operation was seventy-one years (range, forty-one to ninety-two years) and the mean weight was seventy kilograms (range, forty-eight to 105 kilograms). Eleven of the 100 patients died during the follow-up period, all with the implant in place. Of the eighty-nine surviving patients, one had a revision arthroplasty for aseptic loosening. The mean duration of clinical follow-up for the remaining eighty-eight patients was seven years (range, six to eight years). The mean Harris hip score at the latest follow-up evaluation was 91 points (range, 68 to 97 points). Of the eighty-eight patients, eighty-five (97 percent) had a good or excellent result. Radiographic follow-up was performed for eighty-one patients; none had evidence of loosening of the stem, and five (6 percent) had endosteal cavitation but were asymptomatic. The rate of failure (loosening or revision) of the femoral component in the entire series was 1 per cent (one hip). The low rate of failure and the maintenance of good and excellent clinical and radiographic results during this period of follow-up are consistent with reports from other institutions. This strengthens the argument to retain or widen the existing indications for the insertion of a femoral stem with cement in primary total hip arthroplasty.

Revision total hip arthroplasty with the BIAS (Biologic Ingrowth Anatomic System) femoral component. Three to six-year results.

The BIAS femoral component was used for most of the revision total hip arthroplasties performed during a four-year period by one surgeon. Forty-one BIAS femoral components were implanted in thirty-nine patients and were followed prospectively for a mean of five years (range, three to six years). The mean age of the patients was fifty-seven years. Twenty-eight (68 percent) of the femora were classified preoperatively as having severe loss of bone distal to the intertrochanteric line. Cancellous autogenous graft from the iliac crest or fresh-frozen cancellous allograft was used in all hips to fill the proximal defects. Weight-bearing was delayed for three months after the operation. Clinical and radiographic evaluation was performed with the use of accepted criteria. The mean preoperative Harris hip score was 36 points (range, 0 to 71 points) and improved postoperatively to 85 points (range, 53 to 100 points). Thirty-two (78 percent) of the hips had a good or excellent result at the most recent follow-up examination. Thirty-six patients (thirty-eight hips [93 percent]) had no or slight pain, and twenty-nine patients (thirty hips [73 percent]) walked with a slight or no limp. There was an association between one or more previous revisions of the femoral component and an increased prevalence of pain in the thigh or hip (p < 0.009). Radiographic analysis showed that thirteen components (32 percent) subsided, but eleven of them stabilized and subsidence was not associated with less satisfactory clinical results. The hip scores were not notably lower in this group. No component was revised, and no patient had clinical symptoms for which revision was indicated at the most recent examination. Revision total hip arthroplasty with use of this implant, which has a partial proximal porous coating and which is inserted without cement, provided similar clinical results but inferior fixation, as seen on radiographs, compared with reported revisions in which components were implanted with modern cementing techniques. However, the apparent reconstitution of femoral bone structure in areas of previous osteolysis or cortical thinning is encouraging. The senior one of us no longer routinely uses this specific implant for revision arthroplasty done without cement, but does use a similar, revised version of the prosthesis.

The influence of patient-related factors and the position of the acetabular component on the rate of dislocation after total hip replacement.

The senior one of us performed 438 primary and 181 revision total hip arthroplasties with use of so-called modern prostheses between July 1983 and January 1994. Fifty-three patients, who had had forty-seven primary procedures and twelve revisions, either died or were lost to follow-up less than two years after the operation and were excluded from the study. The results for the remaining 446 patients (391 primary procedures and 169 revisions) were analyzed to determine the influence of patient-related and operative factors and the position of the acetabular component on the rate of dislocation. Dislocation occurred after thirty-two (6 per cent) of the 560 total hip arthroplasties: seventeen (4 per cent) of the 391 primary procedures and fifteen (9 per cent) of the 169 revisions (p = 0.046). There was no relationship between the variables of age, gender, obesity, or preoperative diagnosis and dislocation after either primary or revision arthroplasty. Seven (23 per cent) of the thirty arthroplasties in the patients who had a history of excessive intake of alcoholic beverages (more than 2.1 liters [seventy-two ounces] of beer or more than 0.2 liter [six ounces] of other alcoholic beverages a day) were followed by a dislocation compared with twenty-five (5 per cent) of the 530 arthroplasties in the patients who did not have such a history. This difference was significant for the patients who had had a revision arthroplasty (p = 0.00005), but with the numbers available we could not detect a difference for those who had had a primary arthroplasty (p = 0.264). Radiographic analysis was performed for thirty-two hips that had dislocated and thirty-two that had not (seventeen primary procedures and fifteen revisions in each group), matched exactly according to the type of prosthesis and the operative approach (but not age). We detected no association between either the version or the abduction angle of the acetabular component (within the range of 39 to 56 degrees for the primary prostheses and 38 to 57 degrees for the revision prostheses) and the risk of dislocation. Thirty of the thirty-two hips in each group had an abduction angle of the acetabular component that was in the so-called safe range of 30 to 50 degrees.

Charnley total hip arthroplasty with use of improved techniques of cementing. The results after a minimum of fifteen years of follow-up.

Three hundred and fifty-seven consecutive Charnley total hip arthroplasties were performed in 320 patients with use of a so-called second-generation technique of cementing between July 1976 and June 1978. This technique includes use of a distal femoral intramedullary cement plug, hand-mixing of the cement, and use of a cement gun to deliver the cement into the femoral canal in a retrograde fashion. At the time of the latest follow-up evaluation, a minimum of fifteen years after the arthroplasty, 130 patients (142 hips) were still alive, 189 patients (214 hips) had died, and one patient (one hip) had been lost to follow-up. A radiograph was made for 116 (82 per cent) of the 142 hips in the 130 surviving patients. Of the 356 hips that had not been lost to follow-up, thirty-three (9 per cent) had had a revision and two (1 per cent), a Girdlestone resection arthroplasty during the follow-up period. Nineteen hips (5 per cent) were revised because of aseptic loosening of the femoral or acetabular component, or both (two hips); seven (2 per cent), because of loosening with infection; and seven (2 per cent), because of dislocation. The two resection arthroplasties were performed because of loosening with infection; both were done in patients who died before the time of the latest follow-up evaluation. Of the 142 hips in the 130 patients who were alive at a minimum of fifteen years, twenty-two (15 per cent) had been revised: fifteen (11 per cent), because of aseptic loosening; three (2 per cent), because of loosening with infection; and four (3 per cent), because of dislocation. Revision of the femoral component because of aseptic loosening (excluding components that were revised because of dislocation or infection) was performed in four (1 per cent) of the entire series of 356 hips and in three (2 per cent) of the 142 hips in the 130 patients who survived for at least fifteen years. Two of the 356 hips and two of the 142 hips had aseptic loosening of the acetabular as well as the femoral component at the time of the revision. Loosening of the femoral component, defined as aseptic loosening leading to revision or as definite or probable radiographic loosening, occurred in ten (3 per cent) of the 356 hips and in six (5 per cent) of the 116 hips for which radiographs were made at a minimum of fifteen years. The acetabular component was revised because of aseptic loosening in seventeen (5 per cent) of the entire series of 356 hips and in fourteen (10 per cent) of the 142 hips in the 130 patients who survived for at least fifteen years. The acetabular component loosened without infection in forty-one (12 per cent) of the 356 hips and in twenty-six (22 per cent) of the 116 hips for which radiographs were made at a minimum of fifteen years. In two of these patients, the femoral component was also revised. Thus, of the entire series of 356 hips, two had a revision of the femoral component alone because of aseptic loosening; fifteen, a revision of the acetabular component alone; and two, a revision of both components. Of the 142 hips in the 130 patients who survived for at least fifteen years, one was revised for loosening of the femoral component alone; twelve, for loosening of the acetabular component alone; and two, for loosening of both components. These findings demonstrate long-term durability of fixation of the femoral component but less reliable fixation of the acetabular component, even when the surgeon is experienced and improved techniques of cementing are used.

The effect of superior placement of the acetabular component on the rate of loosening after total hip arthroplasty.

A method for measurement of the true acetabular region and the approximate femoral head center as well as a classification consisting of four zones for assessment of the acetabular position of the acetabular cup were used to analyze the results of primary total hip arthroplasty with cement in 117 patients (145 hips). All patients had Crowe type-II congenital dysplasia of the hip. The mean age at the time of the arthroplasty was fifty-one years (range, fifteen to seventy-six years), and the mean duration of follow-up was fourteen years (range, two to twenty-two years). The initial position of the acetabular cup outside of the true acetabular region and outside of zone 1 (inferior and medial) was associated with an increase in the rates of loosening (p < 0.05) and revision (p < 0.04) of the femoral components. Cups that initially were more than fifteen millimeters superior to the approximate femoral head center, without lateral displacement, were associated with an increased rate of loosening (p < 0.001) and of revision (p < 0.04) of the femoral components as well as with an increased rate of loosening (p < 0.002) and of revision (p < 0.01) of the acetabular components. These findings suggest that superior positioning of the acetabular component, even without lateral displacement, leads to increased rates of loosening of the femoral and acetabular components. An attempt should be made to position the acetabular component in or near the true acetabular region.

Dislocations after total hip arthroplasty.

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.

Acetabular anatomy and the transacetabular fixation of screws in total hip arthroplasty.

An anatomical and radiographic study was undertaken to determine the safest zones in the acetabulum for the transacetabular placement of screws during uncemented acetabular arthroplasty. To avoid injury to intrapelvic structures, which are not visible to the surgeon during placement of the screws, cadavera were studied to define the location of these structures with respect to fixed points of reference within the acetabulum. Four clinically useful acetabular quadrants were delineated. The quadrants are formed by drawing a line from the anterior superior iliac spine through the center of the acetabulum to the posterior fovea, forming acetabular halves. A second line is then drawn perpendicular to the first at the mid-point of the acetabulum, forming four quadrants. The posterior superior and posterior inferior acetabular quadrants contain the best available bone stock and are relatively safe for the transacetabular placement of screws. The anterior superior and anterior inferior quandrants should be avoided whenever possible, because screws placed improperly in these quadrants may endanger the external iliac artery and vein, as well as the obturator nerve, artery, and vein. The acetabular-quadrant system provides the surgeon with a simple intraoperative guide to the safe transacetabular placement of screws during primary and revision acetabular arthroplasty.

Structures at risk from medially placed acetabular screws.

The anatomical structures adjacent to fourteen acetabula were studied to identify structures that are at risk from acetabular screws. There were six embalmed acetabula, four acetabula from two fresh autopsy specimens, and four acetabula that were studied during two gynecological operations. Models were constructed to show where these screws can penetrate. Medially placed screws either penetrated or came dangerously close to the external iliac vein; the obturator artery, nerve, and vein; and tributaries of the internal iliac vein. To avoid injury to the medial vascular structures, screws should not be placed in the anterosuperior quadrant of the acetabulum.

Shelf arthroplasty in patients who have Legg-Calvé-Perthes disease. A study of long-term results.

We reviewed the long-term functional and roentgenographic outcomes of severe Legg-Calvé-Perthes disease in two similar groups of patients, one of which was managed with a shelf arthroplasty and the other, by a variety of non-operative means. Twenty hips in nineteen patients were treated with traction and, when necessary, adductor tenotomy to attempt reduction of the subluxation; this was followed by a shelf arthroplasty to increase the arc of the acetabulum and result in coverage of the femoral head. The average duration of follow-up was nineteen years (range, two to forty-seven years). The initial center-edge angle and the anteroposterior Mose sphericity measurement were significantly improved at the most recent follow-up (p greater than or equal to 0.05), and the average Iowa hip score was 91 points. Hinge abduction, which was producing incongruity, was eliminated in eleven of fourteen hips after the operation. The outcomes for the second group, consisting of eighteen hips in seventeen patients who were managed non-operatively, were also reviewed, at an average duration of follow-up of twenty-eight years (range, seven to forty-five years). No significant improvement in the center-edge angle or the anteroposterior Mose sphericity measurement was observed at the most recent follow-up, and the average Iowa hip score was 81 points. There was no significant difference in the range of motion of the hip between the groups. We believe that shelf arthroplasty is a favorable option in the treatment of Legg-Calvé-Perthes disease when additional bone is needed at the lateral aspect of the acetabulum to cover the extruded portion of the femoral head, to prevent additional incongruity and thereby delay the early onset of degenerative changes.