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Background Uncemented femoral components in primary THA are in widespread use, especially in patients younger than 50 years, but few studies have evaluated their survival into the late third and early fourth decade. Questions/purposes We evaluated (1) survivorship using femoral revision for any reason as the endpoint, (2) survivorship using femoral revision for aseptic loosening as the endpoint, (3) survival in patients younger than 50 years, (4) cumulative incidence of stem revision for periprosthetic femoral fracture and (5) the overall risk of revision (change of any part of the implanted components) at a minimum of 27 years of follow-up with an uncemented tapered titanium stem still in clinical use today. Methods We reviewed the clinical and radiographic results of 326 THAs performed in 326 patients (for 28 patients with bilateral THA, only the first hip was included in the analysis to ensure independent observations) using an uncemented grit-blasted, tapered collarless titanium alloy (TiAl6Nb7) stem between January 1985 and December 1989. In that same timeframe, we performed 1038 primary THAs. During that time, we used cementless stems in patients without severe femoral canal deformity and adequate bone stock for uncemented femoral fixation as determined by using the indication criteria described by the developer. In all, 34% (354 of 1038) were cementless; all cementless stems implanted during that time were the stem being studied here. No others were used. The mean (range) age at the time of surgery was 56 years (13-81 years). Sixty-seven patients were younger than 50 years at the time of primary THA. A competing risk survivorship analysis was used to estimate long-term survival. The minimum follow-up was 27 years (mean 28 years; range 27-32 years); at that time, 169 patients had died, and four patients were lost to follow-up. Results Survivorship at 28 years with revision of the femoral component for any reason as the endpoint was 87% (95% CI 83 to 90). Survivorship for femoral revision for aseptic loosening as the endpoint was 94% at 28 years (95% CI 90 to 96). Survival in patients younger than 50 years at the time of primary THA was 89% (95% CI 78 to 95) and 95% (95% CI 86 to 98) at 28 years for the endpoints of all stem revisions and aseptic stem loosening, respectively. The overall cumulative incidence of stem revision for periprosthetic femoral fracture was 4% (95% CI 2 to 7) at 28 years. The overall THA survival rate at 28 years with revision for any reason as the endpoint was 57% (95% CI 51 to 62). Conclusions Uncemented femoral fixation of a tapered collarless titanium alloy stem was reliable into the early fourth decade, especially in patients younger than 50 years. Late stem failures in the third and early fourth decade were mainly because of periprosthetic femoral fracture, while aseptic loosening occurred in undersized stems during the early second decade. Level of evidence Level IV, therapeutic study.

Despite the high level of survivorship of cemented and uncemented stemmed components, there is a need for a joint prosthesis that does not invade the femoral canal. This type of prosthesis would be useful in treating younger and more active patients, in whom the use of such a design would usefully prolong the time before a conventional total joint replacement design was necessary. We present the rationale for a femoral neck prosthesis and show its feasibility as an off-the-shelf system based on a morphologic analysis of the proximal femur. The new design concept consists of a barrel with longitudinal flutes that enters the neck of the femur, loads on the calcar, and contacts the lateral cortex below the greater trochanter. Areas of porous ingrowth are placed so that the load transfer between the implant and the bone resembles that of the two main trabecular patterns in the proximal femur. A new method, cluster analysis, was used for defining a set of 12 sizes that could fit a population of femurs with acceptable dimensional discrepancies. We conclude that this type of device could be implanted reproducibly so that it was a close fit against the target areas of bone in the proximal neck area and against the lateral cortex.

Cementing technique has a profound influence on the incidence of aseptic loosening of total hip replacements. Two specific measures that seem to have the greatest impact on the longevity of cemented femoral stems are pressurization of cement and control of mantle thickness, typically through the use of modular centralizing devices attached to the tip of the prosthesis. Two laboratory studies are presented that examine the success of these measures in clinical practice. In the first study, the performance of five designs of intramedullary plugs in resisting migration during pressurization of cement was evaluated in human anatomic specimen femurs. Profound differences were observed between the performance of the different plug designs. In canals larger than 12 to 14 mm, most commercial devices failed to resist pressures greater than 30 to 40 pounds per square inch. Overall, it was estimated that between 6% to 76% of these devices would fail to resist cement pressures of 50 pounds per square inch in clinical practice. The second study examined the role of distal centralizers in the accumulation of air bubbles around the distal tip of the prosthesis during insertion of the stem into the femur. Acrylic replicas of a femoral stem were implanted in cavities simulating the femoral canal. Colored dyes, present within the cement, revealed the complex patterns of cement flow. It was shown that cement, dragged from the top of the femur, forms a thin layer that covers the entire surface of the prosthesis and the distal centralizer. Significant voids were present behind the trailing edges of the distal centralizer in 42% of the cases examined. These studies show that improvements in intramedullary plugs and stem centralizers are needed to increase the reproducibility of cement technique in total hip replacement.

The direct anterior approach in THA is an intermuscular approach that requires no muscle detachment. However, it is difficult to elevate the proximal femur for access to the femoral canal.We asked (1) which part of the capsule should be released to allow effective elevation of the proximal femur; (2) whether the release of the internal obturator tendon allows elevation; and (3) whether hip hyperextension reduces the ability to elevate the femur.We conducted a cadaver study and a clinical study. In the first study, the elevation of the proximal femur was measured in 6 hips in 3 cadavers after excision of the anterior capsule, after the release of the superior capsule or the posterior capsule, after the release of the superior and posterior capsule, and after the release of the internal obturator tendon under traction of 70 N. Each hip was positioned at 0°, 15°, and 25° hyperextension. In the second study of 39 patients, the posterior capsule was released after the superior capsule in the first 13 hips, and the superior capsule was released after the posterior capsule in the next 26 hips. The elevation achieved for each hip was measured as in the cadaver study.In our cadaver study, hip elevation increased after superior capsule release but not after release of the internal obturator tendon. After superior capsule release, the ability to elevate the femur was not diminished by hip hyperextension. In our clinical study, elevation increased after superior capsule release.Superior capsule release was most effective of all releases for elevating the proximal femur in the direct anterior approach.

Tapered femoral components were designed to provide a cementless alternative in patients with narrow femoral canals. Major concerns with this stem include perioperative fracture and thigh pain. To ascertain the frequency of these concerns, we retrospectively reviewed 100 consecutive hips in 97 patients who underwent total hip arthroplasty with a tapered fibermetal femoral component. Patients were evaluated postoperatively using Harris hip scores and sequential radiographs. The average age of the patients was 56.5 years (range, 33.7-73.5 years). Minimum followup was 5 years (average, 6.2 years; range, 5-9 years). One patient died at 1.3 years and was excluded from the study. Six patients had incomplete perioperative fractures of the calcar without extension below the lesser trochanter. All fractures were recognized perioperatively and fixed with cerclage wires without further problems. Four patients underwent revision surgery, two for recurrent dislocation secondary to malpositioning of the acetabular cup, one for a greater trochanteric fracture after a fall, and one for a fractured zirconium femoral head. At last followup, the mean Harris hip score was 98 (range, 86-100); two patients had mild anterior thigh pain. All femoral stems appeared to have bony integration radio-graphically. Tapered femoral stems provide a cementless alternative in patients with a narrow femoral canal without undue risk of perioperative fracture or thigh pain.

Femoral revision with a 7-inch or 8-inch fully porous-coated stem may not provide reliable longterm results in patients with moderate bone loss. The purpose of this study was to evaluate the limits of fully porous-coated stems and to create a treatment algorithm for femoral deficiencies. Fifty) one patients with either a 10-inch or 9-inch calcar fully porous-coated stem, 10 patients with impaction bone grafting, and 10 patients with a modular tapered stem were evaluated at an average 4.2 years postoperatively. The mechanical failure rate among the 9-inch and 10-inch fully porous-coated stems was 0% in Type III B defects with femoral canals less than 19 mm (15 patients), 18% in Type IIIB defects with femoral canals greater than 19 mm (2 of 11 patients) and 37.5% in Type IV defects (three of eight patients). There were no mechanical failures observed among the bone packing or modular tapered stems. Patients with Type IIIB defects and a femoral canal less than 19 mm can be treated successfully with either a 10-inch or 9-inch calcar fully porous-coated stem. However, patients with a Type IIIB defect and an endosteal canal greater than 19 mm or a Type IV defect require alternative methods of reconstruction such as a modular tapered stem or a bone packing procedure.

Treatment of patients with osteonecrosis of the femoral head focuses on pain relief and improved function of the hip. Total hip arthroplasty remains an effective tool for the treatment of patients with end-stage osteonecrosis with collapse of the femoral head, although there is a greater risk for failure. The aim of the current study was to assess the long-term survival of cementless total hip arthroplasties in 28 patients (36 hips) with osteonecrosis of the femoral head (Steinberg Stage V and Stage VI) with an average followup of 11.2 years (range, 10-15 years). There were 19 women and nine men with an average age of 51.4 years (range, 28-65 years). A threaded titanium cup CST (Conical Screwed Titanium) was used in all patients and different cementless femoral components were used depending on the optimal fit in the femoral canal as assessed during preoperative templating. No serious complications were encountered postoperatively. The patients were evaluated preoperatively and postoperatively with the Merle d'Aubigne and Postel scale. After cementless total hip arthroplasty, the average pain score improved 3.6 points, walking ability improved 1.6 points, and range of motion improved 1 point. Two patients had thigh pain. Radiographic evaluation on anteroposterior and lateral radiographs of the proximal femur was excellent in 10 hips postoperatively. No heterotropic ossification was observed, although proximal femoral atrophy was seen in 15 hips. Clinical and radiologic findings did not correlate. There were two revisions of the acetabular implants in one patient with bilateral idiopathic osteonecroses and total hip replacement. Overall, survival of the prostheses was 93.4% at the average followup of 11.2 years.

There is evidence in several animal and human studies that high intramedullary pressure in the femur is of causal significance for bone marrow release into the circulation, causing pulmonary fatty marrow embolization. A previous clinical study provided evidence that in uncemented hip arthroplasty, high intramedullary pressure and subsequent fat embolism with cardiorespiratory deterioration can occur. In this prospective clinical trial, the effect of five surgical techniques on the femoral intramedullary pressure was recorded intraoperatively in 36 patients during uncemented press fit hip arthroplasty. In Group A, the conventional surgical technique (slide hammer and femoral rasps) showed intramedullary hypertension during opening of the femoral canal, femur preparation, and prosthesis insertion. In Group B, a mechanical high frequency vibration rasp was used, instead of the slide hammer, and provided reduction of the intramedullary pressure peaks during opening of the femoral canal but could not prevent intramedullary hypertension during rasping and prosthesis insertion. In Group C, a modified surgical technique to prevent high intramedullary pressure reduced pressure peaks during opening of the femoral canal and resulted in a significant reduction of intramedullary pressure during femur preparation and prosthesis insertion compared with the conventional surgical technique used with Group A. In Group D the results of the modified surgical technique could be improved additionally by using the high frequency vibration rasp, instead of the slide hammer. In Group E conventional surgical technique in combination with a distal venting hole has not proven to be efficient in uncemented hip arthroplasty. Based on the results of this in vivo study, the proposed modified surgical technique in cementless hip arthroplasty can be recommended to avoid high intramedullary pressure peaks, which should minimize the risk of significant bone marrow release into the circulation and the risk for cardiorespiratory deterioration caused by fat embolism.

The angle formed between the femoral anatomic axis and the femoral prosthesis was measured on radiographs of 201 total knee arthroplasties. The radiographs were taken on a 51 inch x 14 inch cassette and had to have satisfactory centering and minimal rotation to be included. All total knee arthroplasties had intramedullary femoral alignment. The mean femoral component angle (relative to the femoral anatomic axis) was 6.1° valgus, with a standard deviation of 2° and a range from 2° to 12° valgus. Seventeen knees (8.5%) had a femoral component angle that was ≤2° valgus or ≥10° valgus. In 4 knees, medial femoral bowing of the distal third of the femoral shaft caused an excessive valgus cut. In 7 knees, a capacious femoral canal was present that potentially allowed for divergence of the relatively undersized guide rod in the canal. Overall, 8.5% of cuts were believed to be less than ideal. Preoperative radiographs of the entire femur should identify patients in whom errors are more likely and allow for templating the amount of distal femoral bone to be resected. Extra caution is needed in bowed femora and in capacious femoral canals.

This study describes the biologic integration of grit-blasted titanium alloy (Ti-6Al-4V) implants that were press fit into the distal femoral canal of young adult rabbits and evaluated by histologic, histomorphometric, and biomechanical methods. Polished and aluminum oxide grit-blasted (4.2 ± 0.7 microns surface roughness) solid implants were compared with titanium fibermetal implants. Nondecalcified cross sections were studied by histology, histomorphometry, and electron microscopy in the backscatter mode at 3, 6, and 12 weeks after implantation. Pullout strength was measured at 12 weeks. Data were analyzed by analysis of variance and post-hoc Student-Newman-Keuls and Scheffe's tests. The blasted implants had significantly more bone intimately in contact with the implant surface (31%) than the fibermetal (17%), or solid polished implants (15%). By 3 weeks, woven bone had formed directly on the surface of the blasted implants, whereas there was a discrete space between woven bone and the other implants. Active remodeling of bone was shown by fluorochrome uptake at the surface of the blasted implants at 12 weeks after implantation. The strength of fixation of blasted and fiber-metal implants was significantly greater than polished implants at 12 weeks after implantation. Direct attachment of newly formed bone onto the blasted implant surface was confirmed by backscatter electron microscopy. The results of this study indicate that grit-blasted titanium surfaces provide an excellent surface for bone-implant integration.

Unilateral cemented hip hemiarthroplasty was done on 16 dogs who subsequently had revision arthroplasty and who were divided into 1 control and 3 experimental groups: The first group had cement extraction using osteotomes; the second, using a high speed burr; the third, an ultrasonic tool. Hemodynamic and transesophageal echocardiographic monitoring were done. Postmortem pulmonary specimens were examined for differences in the quantity of fat emboli. There was a significant increase in emboli with the ultrasonic tool as compared with osteotomes and high speed burr. There was no significant difference in emboli between the osteotomes and high speed burr. Fat emboli syndrome is related to mechanical compression of the femoral canal. The ultrasonic instrument was unique in its tendency to cause large embolic showers, especially during extraction of the distal cement plug. In these young dogs, minimal hemodynamic changes and no cardiac dysrhythmias occurred, which in part may be attributed to their good health. These changes may remain subclinical for patients with good cardiorespiratory reserve, or may become life threatening for those with poor reserve. By outlining the mechanisms of fat embolism in revision total hip arthroplasty, it may be possible to decrease future morbidity, especially in patients who frequently have cardiopulmonary disease.

Cement removal in revision total hip arthroplasty can be technically challenging. Traditional methods involve using a combination of chisels, power burrs, and drills, as well as windowing the femoral cortex to gain access to cement distally. These methods can be associated with femoral fracture or uncontrolled cortical perforation and bone loss. A new technique had been developed that permits segmental extraction of bone cement from the femoral canal. Fresh cement is introduced into the old cement mantle and a threaded rod is placed into the wet cement and held in place while the cement hardens

The results of the first and second groups of 50 consecutive primary, uncemented porous-coated anatomic arthroplasties were analyzed to evaluate the learning curve associated with the procedure. Femoral fit, acetabular cup angle, femoral fracture rate, minimum two-year clinical hip ratings, and clinical symptoms were compared between the two groups. Significant improvement in achieving better femoral canal filling with the prosthesis and lower acetabular cup angle placements was documented in the second 50 cases. Although a definite learning curve in mastering the technique of uncemented total hip arthroplasty was observed, thigh pain rate and clinical ratings were not improved after two years.

Venous thromboembolic disease remains the most common and potentially fatal complication after total hip arthroplasty (THA). Proximal femoral deep vein thrombosis (DVT) is especially prone to propagate and embolize. The authors' hypothesis was that intraoperative intravenous heparin administration could reduce proximal DVT in THA. There were 286 patients who entered into a prospective, double-blind, randomized clinical trial at the authors' institution between June 1988 and May 1990. All patients had unilateral primary THA under hypotensive epidural anesthesia. The epidural catheter was placed at least 60 minutes before heparin administration. Intravenous heparin was given during surgery only. All patients received aspirin twice daily (650 mg/day) after surgery. Detection of DVT was by contrast venography on Postoperative Day 6 or 7. The study was divided into three phases. There was four groups: control (intraoperative saline), 30 minutes (1000 U heparin at beginning of surgery followed by 500 U every 30 minutes), continuous adjusted (1000 U or 1500 U initial bolus followed by continuous heparin infusion maintaining anticoagulation at 30%-50% elevation from baseline), and fixed dose (1000 U bolus before hip dislocation, and 500 U bolus before femoral canal preparation). Proximal femoral DVT was effectively reduced from 9.1% in the control group to 1.7% in the heparin groups (1.7% in 30 minute, 1.6% in continuous adjusted, 1.7% in fixed dose) (p less than 0.02). The overall DVT rate was also significantly reduced from 24.3% to 10% (p less than 0.01). No adverse effects from heparin administration were noted. Postoperative drainage, hematocrit levels on Postoperative Day 2 and at discharge, and transfusion requirements were not significantly different among the groups. The current recommended protocol is 1000 U bolus five minutes before hip dislocation, followed by 500 U bolus five minutes before femoral preparation. This, in conjunction with hypotensive epidural anesthesia and postoperative aspirin, is effective in reducing proximal DVT to less than 2% in primary THA.

Large amounts of metal and polyethylene debris and high ion readings are found in capsule and fibrous membranes of both loose titanium and cobalt-chromium stems. Prostaglandin E2, interleukin-1, and collagenase levels are elevated when compared to control values with collagenase having the highest and most consistent elevations. Synovial fluid and blood ion readings were elevated in loose cemented and cementless stems made from both materials. Blood ion readings were not elevated in fixed stems. Fixed stems had much less particulate debris in soft tissues. The data showed that failure of most metal hip stems was initially due to a mechanical cause, with high debris and ion counts occurring secondarily in capsule and fibrous membranes. Particulate debris and high ion readings are primarily a focal problem contained by the periprosthetic fibrous connective-tissue encapsulation within the femoral canal and joint capsules. No systemic problems were manifest in any of the patients examined and followed in this study.

Removal of cement from the femoral canal during total hip revision arthroplasty continues to be very challenging. The technique is described using multiple 9-mm perforations placed at least 5 cm apart on the anterior surface of the femoral shaft. The tip of the revision stem should be at least 5 cm distal to the most distal perforation. From January 1984 to December 1986, 219 cases of revision total hip arthroplasties were performed using this technique; the incidence of ipsilateral postoperative femoral fractures was nine out of 219. Eight of these fractures were at the tip or distal to the femoral prosthesis and were associated with trauma. One fracture occurred through a perforation site and had an associated fracture of the femoral component. This method appears to be a reliable and safe method of cement removal from the femoral canal.

More than 500 hips, with either displaced fractures of the femoral neck or primary or revision total hip arthroplasty, were treated by a straight, long-stem (305-mm), Bateman-type bipolar model (BBM). The BBM was not porous coated, and it is not cemented in place. The femoral component is secured in the femoral canal by means of biomechanical fixation. It is biologic by bone ingrowth through the fenestration in the proximal neck. It is mechanical by a snug fit in the isthmus and by three-point fixation within the shaft. The removed femoral head is morselized in the bone mill and packed into the prepared femoral canal to enhance a tight fit. The collar of the BBM transfers stress to the calcar. Postoperative roentgenograms show incorporation of bone graft within the fenestration of the prosthesis and no stress shielding of the calcar. The acetabulum requires reaming only if it is shallow or asymmetric. It usually presents no problem except in revision total hip arthroplasty. The present authors have used the BBM almost exclusively since 1981. After eight years, the BBM has stood up well to the test of time and presented few major problems.

Congenital dysplasia, treated or untreated, produces a hip joint difficult to reconstruct and is even more difficult when coxarthrosis supervenes producing significant disability. Total hip replacement can be dramatically successful in these patients, and equals those with coxarthrosis without congenital dislocation. The acetabulum must be totally reconstructed and relocated as near as possible to its original orientation. Usually a small straight stem femoral component must be placed into a generally constricted femoral canal. A thoughtful preoperative plan including X-ray templates is absolutely essential for a successful reconstruction without postoperative complications.

Three femoral components (one cemented and one uncemented straight-stem Muller and one uncemented Anatomic Medullary Locking) were placed into cadaveric or commercially available plastic femora to establish that rotation of the femur can simulate changes in femoral component alignment on the anteroposterior radiograph. The change in alignment is governed by the position of the prosthesis within the femoral canal. If the stem of the prosthesis is positioned posteriorly in the canal, external rotation simulates valgus; internal rotation results in a varus orientation. If the prosthetic stem is located anteriorly in the canal, the reverse is true. This effect was noted in all specimens for values as small as 20 degrees of rotation. Because a change in the position of a prosthesis may signify loosening, it is recommended that standardized positioning techniques be used for radiographic analysis of total hip arthroplasties.

A segment of the rabbit radius diaphysis was excised, demineralized, and pulverized. The demineralized matrix particles were mixed with autologous bone marrow from the femoral canal and injected into the defect from which it had been excised. On the contralateral side, the demineralized bone was reimplanted without pulverization, but with bone marrow. The bone yield was measured by radiographic planimetry and Tc99m MDP scintimetry. The forearms of the rabbits were sectioned into transverse segments, including the middle of the radius defect. The ash weights and the Ca45 content of these segments were measured. After two weeks, the ash weight was greater on the pulverized than on the unpulverized side; but by four weeks, measurements showed no difference. In general, the injectable bone matrix preparation did not interfere with bone repair. In comparing the Tc99m and Ca45 methods, the latter provided high-precision data with respect to the biologic variation.

Aseptic loosening is the most common cause of femoral component failure following total hip arthroplasty (THA). Improvements have been made in cementing technique, but little attention has been directed toward the effect of different femoral components on bone cement pressurization. The effect of three different femoral stem sizes in one femoral canal and of eight different femoral stem designs on bone cement extrusion pressures was investigated on autopsy specimens. In a given femur significant increases in bone cement pressurization were achieved about the distal two-thirds of the femoral component in progressing from a small to a medium to a large stem. Similarly, femoral stems with rounded, rectangular cross sections generated greater bone cement pressurization about the distal two-thirds of the stems than stems trapezoidal and diamond-shaped in cross section due to their increased stem volume. The results of this study favor the use of the largest femoral component stem, preferably one with a rounded, rectangular cross section, that will fit comfortably in a given femoral canal and still allow a surrounding cement envelope such that bone cement pressurization will be enhanced with implant introduction.

A retrospective clinical and roentgenographic review was performed on 251 consecutive cemented total hip arthroplasties (THA) performed from 1978 to 1980 that had been followed a minimum of five years (range, five to seven years). All arthroplasties involved the use of a Harris Design II femoral stem, an intramedullary plug, a cement gun, and pulsatile lavage of both the acetabulum and the femoral canal. At the final follow-up examination, 98% of the patients had excellent results. The average Harris hip score was 47 points preoperative and 97 points postoperative. There were three definitely loose femoral stems, one probably loose, and two possibly loose. There was one loose acetabular component, no revisions or operations were performed. When comparing this series with a similar study, there were statistically improved results in all parameters. Results from this study of cemented THAs using contemporary techniques and prosthetic stem design represent the standard for comparison when evaluating alternative THA systems.

Bone-acrylic interface pressure measurements were recorded at the medial interior rasped surfaces of fresh cadaver femurs during digital packing of acrylic bone cement and during insertion and seating of a Trapezoidal-28 femoral total hip component. Plugging of the femoral canal below the tip of the prosthesis stem was an effective means for increasing pressure in the distal femoral canal when the stem was inserted in the early stages of acrylic polymerization (i.e. immediately after dough time). At surgery, this can be accomplished by inserting a small bolus of acrylic down the canal to a depth below the tip of the seated stem and allowing it to polymerize in place. This forms an effective seal which prevents distal extrusion of the acrylic when the cavity is then packed prior to prosthesis insertion. Elimination of cement in the distal canal also avoids any future difficulty of acrylic removal should revision become necessary due to loosening or infection. No significant pressure differences were observed between one and two millimeter thicknesses of acrylic between the metal and bone. Interface pressures developed during finger packing were of the same order of magnitude as those achieved during seating of the femoral component. Use of a rubber diaphragm stretched tightly over the margins of the rasped femoral cavity helped to contain the acrylic and prevent extrusion during finger packing but was ineffective in increasing interface pressure. When this method is used, the acrylic can be poured or injected into the canal and packed before dough stage and thus facilitate increased cancellous penetration when the acrylic is in a state of low viscosity.

A series of 1321 total hip arthroplasties including 238 primary revisions (18%) were evaluated to identify intrinsic factors of the femoral canal that might influence the success of a cemented total hip replacement. A survival analysis was used to compare the success rates of cemented femoral components. These were classified into five groups according to the condition of the medullary canal at the time of surgery: primary surgery, aseptic cemented loosening, failed noncemented hemiarthroplasty, previous septic failure, or fractured femoral prosthesis with rigid distally fixed cement. The overall survival rates of the five groups were found to be significantly different (p less than 0.01). Specifically, the success rates of recemented revisions for aseptic loosening were significantly lower than those for primary total hip replacements (p less than 0.01). No statistical difference was found between the success rates of primary surgeries and the revision success rates for septic failure or for a fractured femoral component.

Plugging of the medullary canal during total hip replacement creates better cement fixation and thereby prevents subsequent loosening of the femoral component. Methods of plugging involve the use of cement or bone plugs. Both methods have limitations, are time-consuming and can bae ineffective. A high-density polyethylene plug is convenient material for plugging the medullary canal. Laboratory studies show that the plug generates an intramedullary pressure when the proximal femoral canal is being cemented. In 50 patients undergoing total hip replacement, this bullet effectively restricted the cement cone of the proximal femur. The method of insertion was simple, efficient and expedient.

Intraoperative fractures of the proximal femur occurred in 40 (38 patients) of 630 (6.3%) biological ingrowth total hip arthroplasties performed between January 1984 and July 1986. Twenty-three of these fractures occurred during 131 revision arthroplasties (17.6%) and 17 during 499 primary arthroplasties (3.5%). All but two of the fractures were recognized during surgery. Thirty-seven were treated with either Parham bands or cerclage wires. Bone graft was added to the fracture site in 31 fractures. All of the fractures healed. Three of the patients failed to achieve stable fixation and have required revision surgery. An additional patient has thigh pain with 2 mm of subsidence noted with serial roentgenographs. Femoral fractures can be prevented by preoperative templating of roentgenograms containing markers to measure magnification, routine overreaming of the femoral canal when implanting long-stemmed prostheses, and prophylactically applying wires or bands to femurs requiring the removal of screws.