Mechanical factors in loosening of Christiansen and Charnley arthroplasties

A series of 96 Christiansen and 23 Charnley hip arthroplasties, mainly for osteoarthrosis, were followed for an average of 40 (15-93) months. Radiolucent zones at the cement bone interface and resorption of the calcar were more frequent in the Christiansen than in the Charnley hips. Medial and axial migration, and cement fracture often occurred concurrently, with a total frequency of 27/96 in the Christiansen and 4/23 in the Charnley subseries. Wide radiolucent zones in the acetabular cement bone interface were more frequent in the Christiansen hips. Six acetabular protrusions were observed in the Christiansen hips against none in the Charnley hips. The average Harris' hip scores were significantly higher for the Charnley than for the Christiansen hips. Reoperation for loosening was performed in two Charnley hips and 19 Christiansen hips.     

Mechanical factors in loosening of Christiansen and Charnley arthroplasties

A series of 96 Christiansen and 23 Charnley hip arthroplasties, mainly for osteoarthrosis, were followed for an average of 40 (15-93) months. Radiolucent zones at the cement bone interface and resorption of the calcar were more frequent in the Christiansen than in the Charnley hips. Medial and axial migration, and cement fracture often occurred concurrently, with a total frequency of 27/96 in the Christiansen and 4/23 in the Charnley subseries. Wide radiolucent zones in the acetabular cement bone interface were more frequent in the Christiansen hips. Six acetabular protrusions were observed in the Christiansen hips against none in the Charnley hips. The average Harris' hip scores were significantly higher for the Charnley than for the Christiansen hips. Reoperation for loosening was performed in two Charnley hips and 19 Christiansen hips.     

Can Plate Osteosynthesis of Periprosthethic Femoral Fractures Cause Cement Mantle Failure Around a Stable Hip Stem? A Biomechanical Analysis

Periprosthetic femoral fractures (PFF) are a serious complication after total hip arthroplasty. Plate fixation with screws perforating the cement mantle is a common treatment option. The study objective was to investigate hip stem stability and cement mantle integrity under dynamic loading. A cemented hip stem was implanted in 17 composite femur models. Nine bone models were osteotomised just distal to the stem and fixed with a polyaxial locking plate the other eight constructs served as the control group. All specimens were tested in a bi-axial material testing machine (100 000 cycles). There were no statistically significant differences in axial nor in medial (varus) stem migration. No cement cracks were detected in both groups. Plate fixation of a PFF with a stable, cemented prosthesis did not lead to cement mantle failure in this in vitro study.     

Acetabular prosthetic protrusion and sepsis: case report and review of the literature

Acetabular prosthetic protrusio is an unusual complication of total hip arthroplasty that develops from erosion of the medial acetabular wall and intrapelvic migration of the implant. This report reviews 3 cases of severe intrapelvic prosthetic migration where acute or chronic sepsis was associated with the condition. All subjects were female and involved the left hip. In each case, debridement of the intrapelvic implant was required with an intra-abdominal approach. After successful eradication of infection, 2 patients have a well-functioning reimplanted prosthesis, and 1 was left with a Girdlestone arthroplasty. Literature review revealed that 11 of 16 similar prosthetic protrusion cases had chronic sepsis, of which, 10 were female and 9 involved the left hip. Chronic infection should be considered when intrapelvic prosthetic migration occurs after total hip arthroplasty.     

Primary prosthetic replacement in acute femoral neck fractures

This paper reports a retrospective study of acute femoral neck fractures in 123 patients treated by primary prosthetic replacement. The average age in our patient population was 80.5 years. A Christiansen trunnion-bearing hip prosthesis (Christiansen, 1969 and 1974) was used in all patients except one. The prosthesis was cemented to the femoral shaft. The postoperative mortality rate was low, and the mortality rate was 8.7 per cent.The patients were examined between 6 months and $\text{3}\text{1}\text{2}$ years after operation. Excellent or good results according to Stinchfield's hip assessment system (Stinchfield et al., 1957) were obtained in 82 per cent of the patients. We suggest that primary prosthetic replacementin acute femoral neck fractures in elderly patients is a safe and valuable procedure. However, a definite conclusion concerning this therapy cannot be drawn before a prospective study comparing the results of internal fixation and primary prosthetic replacement is made.     

An evaluation of Trapezoidal-28 femoral stem fractures

Fourteen patients sustaining femoral stem fractures of cold rolled wrought stainless steel Trapezoidal-28 prostheses (Zimmir, Warsaw, Indiana) were compared statistically with 259 successful hip replacements of the same type of prosthesis to determine possible factors predisposing to prosthetic fracture. Varus alignment was the highest contributing factor in these femoral stem fractures. Calcar resorption and insufficient distal lateral cement support also were contributory. Medial cement support was less for patients sustaining a fracture, but this was not statistically significant. Patients prone to encounter a fracture were men who were young and/or overweight. There was no significant correlation of fracture to preoperative diagnosis, laterality, trochanteric osteotomy, nonunion of the greater trochanter, or wire breakage.     

A long term follow-up of Moore arthroplasty in femoral neck fractures.

Moore arthroplasty was performed for medial femoral neck fractures in 169 patients. The mortality rate was 21.3 per cent within 3 months. The general postoperative complication rate (39.6 per cent) was dominated by cardiopulmonary (17.2 per cent) and thromboembolic (16.0 per cent) events. Of local complications, wound infection was found in 4.7 per cent and osteitis in 3.0 per cent of cases. A total of 60 patients were followed up with a mean observation time of 4.9 years. Of these, 8.3 per cent sustained femoral fractures during this period. The results classified according to the criteria of the American Academy of Orthopedic Surgeons showed 52 per cent excellent or good, 43 per cent fair and 5 per cent poor results. The roentgenological finding of settling or osteolysis along the prosthesis was significantly correlated to reduced hip mobility. Ossification in the prosthetic fenestres gave significantly diminished settling, and was correlated to better hip mobility and less pain. In our opinion, Moore arthroplasty has proved to be an acceptable method for the treatment of femoral neck fractures in elderly patients, as 73 per cent had an acceptable range of motion, 40 per cent managed walking distances of more than 500 m and 70 per cent had minimal or no pain. Although 25 per cent became nursing home patients, this reduction of vitality could be related to the hip arthroplasty in only two cases.     

髋关节股骨假体远端中心化状态的定量评估

目的采用CT成像技术评估髋关节置换术后股骨假体远端的中心化状态。方法对18个人工全髋关节股骨假体柄的第4区进行CT扫描,并以股骨髓腔中心为原点,以股骨远端内外后髁连线的平行线作为X轴,建立直角坐标系,对假体柄远端进行测量分析。结果通过CT扫描可以更直观、准确地显示假体柄远端在骨髓腔中的位置。测量所得的圆心距(假体柄远端中心点与股骨髓腔中心点的距离)、股骨髓腔半径以及假体柄尖所在的象限和象限值,可以作为股骨假体远端中心化状态的量化指标。结论由于CT扫描的介入,可以对股骨假体远端中心化状态进行量化观察,为指导临床医生研究和改进手术技术,判断术后临床效果,提供了一种准确、量化的评估方法,也为相关研究提供了可靠的基础。     

Total hip replacement in the previously septic hip

Total hip replacement was performed in either one or two stages in thirty-three hips with active sepsis. The sepsis had followed hemiarthroplasty in six hips, open reduction with internal fixation of a fracture in eight, cup arthroplasty in one, and total hip replacement in eight hips within six years prior to the second total hip replacement. Ten additional patients had total hip replacement following destruction of the hip joint by hematogenous sepsis in nine and by infection following a shrapnel wound in one. Of these thirty-three patients, twenty-three (70 per cent) reveal no signs of infection at three to nine years after prosthetic replacement. Of the remaining ten in whom an infection developed, six had definite recurrences of the original infection, three were infected with organisms different from the original one, and one was either a local recurrence or reseeding from a persistent pyelonephritis. The success rate when the original organism was gram-positive was 78 per cent, including two of three total hip replacements done in the presence of active infection with Staphylococcus epidermidis. The success with gram-negative organisms, however, was only 58 per cent. The prosthetic failure rate was highest in patients who had had a previous infection about a total hip replacement (37 per cent) and in patients who had had a previous infection but no prior prosthetic or internal fixation devices (37 per cent). The lowest prosthetic failure rates were in patients with an infected hemiarthroplasty (16 per cent), an infection around an internal fixation device (25 per cent), or an infected cup arthroplasty. A complete and differential blood-cell count, erythrocyte sedimentation rate, aspiration arthrogram, and radiographs did not effectively predict success or failure. For gram-positive infections, the success rates were similar following either a one or a two-stage procedure. We found that the success rates could be improved by a repeat course of parenteral antibiotics after the total hip replacement even if all preoperative and intraoperative studies failed to identify an infection. Patients with a successful total hip replacement achieved much better functional results than those who had to have a Girdlestone procedure. However, all patients must be carefully assessed prior to reimplantation of a prosthesis because of the high failure rate, especially with gram-negative organisms (Pseudomonas having the gravest prognosis), even when the procedure is done in two stages.(ABSTRACT TRUNCATED AT 400 WORDS)     

Replacement of the Femoral Head by Ceramic Endoprosthesis: An Experimental Study on Rabbits

In 31 rabbits the femoral head was replaced by a ceramic endoprosthesis. For 11 of the experimental animals the endoprostheses were made by the Arabia China Factory in Helsinki, and for 20 by Staatliche Porzellan Manufaktur in Berlin. The operation was performed under fully sterile conditions and the follow-up time was between 6 and 34 weeks. The hip joint was examined clinically, roentgenologically, macroscopically and histologically.

The bending tolerance of the ceramic endoprosthesis was not adequate. Mechanical loosening of the proximal part of the prosthesis occurred in 68 per cent and was combined with fracture of the prosthetic stem. This created a pseudarthrosis-like reaction in the acetabular area and limited the movement of the hip joint. The distal fragment of the stem was always surrounded by a thin layer of dense bone. In the nonfractured cases (32 per cent), however, the reaction was only moderate and the movement of the hip joint was well preserved. The tissue reactions to the ceramic material were slight, but the great number of secondary reactions following stem fractures make the use of the ceramic endoprosthesis questionable in experiments with rabbits.     

Total hip replacement with cemented, uncemented, and hybrid prostheses. A comparison of clinical and radiographic results at two to four years

One hundred and thirty-one patients who had 144 cemented or uncemented hip prostheses were followed prospectively for two to four years. A cemented or a hybrid prosthesis (consisting of a cemented femoral component and an uncemented acetabular component) was used in men older than seventy years, in women older than sixty years, and in younger patients in whom adequate initial fixation could not be obtained without cement. Uncemented, porous-surfaced implants were used in all other patients. The over-all clinical results were similar for the three groups. For the fifty-two hips that had a cemented prosthesis, the mean total Harris hip rating was 91 points and the score for pain, 42 points; for the twenty-seven hips that had a hybrid prosthesis, 90 and 43 points; and for the sixty-five hips that had an implant allowing ingrowth of bone in both the acetabulum and the femur, 95 and 43 points. Two prosthetic stems that were designed to allow ingrowth of bone had aseptic loosening; one was revised. Pain in the thigh, usually slight and not disabling, occurred at one year in 24 per cent of the patients in whom a femoral component allowing ingrowth had been used; the prevalence of pain then declined. The incidences of migration of the components and of radiolucent lines were greater in the acetabula that had a cemented component than in those that had a cup allowing ingrowth of bone.     

Retroperitoneal migration of a septically loose femoral component

Migration of total hip arthroplasty components is generally associated with a medial acetabular wall defect and may cause various intrapelvic complications. This is often a result of the destructive bone loss that takes place with infection. To our knowledge, this is the first report that presents complete intrapelvic migration of a femoral stem of total hip arthroplasty due to septic loosening with an intact medial acetabular wall.     

The CAD hip arthroplasty. Five to ten-year follow-up

One hundred and fourteen total hip arthroplasties in 100 patients were performed using the CAD (computer-assisted design) prosthesis at The Hospital for Special Surgery between 1975 and 1977. Sixty-one of these patients (seventy-four hips) have been followed both clinically and radiographically for a minimum of five years (average, 7.1 years). While no hip required revision before five years, seven hips were revised between six and ten years postoperatively. Ten hips had an excellent result; forty-eight, good; eight, fair; and one, poor. Radiographic analysis revealed narrowing of the cortex of the bone medially at the region of the proximal part of the stem in the hips that were operated on as compared with the contralateral side that was not operated on. Nine hips (12 per cent) had one to two-millimeter radiolucent lines at the femoral bone-cement interface, and in five the lines were progressive. Fourteen hips (19 per cent) had radiolucent lines at the femoral bone-cement interface with a maximum width of 0.5 millimeter. Thirty-four (42 per cent) had more than three millimeters of resorption of the calcar or superomedial cyst formation. Survivorship analysis of the prosthesis predicted a 77 per cent survival rate at nine years. None of the prosthetic stems fractured despite the fact that the population was young, active, heavy, and predominantly male. The incidence of calcar resorption, however, was higher than in other studies. Thus, while the revision rate compared favorably with that of similar studies using other stem designs, compromise of the bone stock of the proximal end of the femur may be a significant disadvantage of this type of prosthesis.     

The effect of two different types of cement restrictors on the femoral cement mantle

Cement restriction and pressurisation are helpful technical points in achieving a good cement mantle in cemented hip replacement. In this prospective study, we compared 39 cases where a Hardinge polyethylene restrictor was used and 33 cases where a bone block restrictor was used during Charnley hip replacement. The preoperative radiographs were templated, calibrated holders for the cement restrictors were used intraoperatively, keeping the distal cement height within 2-3 cm from the tip of the femoral prosthesis. Postoperative radiographs were analysed. The Harris Hip scoring system was used for clinical assessment of results. The preoperative target of having a distal cement height of 2-3 cm was achieved in only 60.6% of the bone block group and 30.6% of the Hardinge group. The difference between the two groups is statistically significant (p = 0.001). Distal migration of the restrictors more than 3 cm from the tip of the femoral prosthesis was associated with a non-homogenous cement mantle in zones 3, 4 and 5 without affecting zones 1, 2, 6 and 7. The cement mantle was adequate when the distal cement mantle remained within 2-3 cm of the tip of the femoral prosthesis.     

Factors contributing to lysis of the femoral neck in total hip arthroplasty

A radiographic analysis of 483 Charnley total hip arthroplasties performed from July 1970 to November 1975 demonstrated that 13% of the hips had lysis of the medial femoral neck. The findings suggest that the lysis of the medial femoral neck is significantly reduced if the femoral stem is oriented in a valgus or neutral position and with at least 5 mm of cement separating the stem of the prosthesis and the medial cortex of the femoral neck.     

Loosening of the femoral component after use of the medullary-plug cementing technique. Follow-up note with a minimum five-year follow-up

Of the 171 total hip replacements reported on previously that had had a minimum length of follow-up of two years, 117 replacements in 104 patients were analyzed at a minimum of five years postoperatively (average, seventy-four months; range, sixty to ninety-four months) to assess the rate of loosening of the femoral component. At the time of cementing of the femoral component, the medullary canal had been plugged with a bolus of bone cement and then filled with doughy Simplex-P methylmethacrylate in a retrograde fashion using a cement gun. The femoral components, made of a chromium-cobalt alloy, had a rectangular cross-sectional shape to the stem and a medial collar. Three categories of loosening were used: definite (requiring radiographic evidence of migration of the component or the cement), probable (requiring evidence of a complete radiolucent zone at the bone-cement interface on one radiograph or more), and possible (a radiolucent zone at the cement-bone interface of more than 49 per cent but less than 100 per cent on one radiograph or more). One femoral component had been removed for aseptic loosening at another hospital, leaving the patient with a resection arthroplasty. One other (1.7 per cent) was definitely loose. No femoral component was categorized as probably loose, and only two were possibly loose.     

Comparison of replacement prostheses for segmental defects of bone. Different porous coatings for extracortical fixation

The extent of extracortical bone-bridging and ingrowth into porous-coated prostheses for the stabilization of segmental defects was studied in a canine model. Initial fixation of the implant was achieved using bone cement. Autogenous bone grafts were applied over the porous-coated segmental portion of the prosthesis to stimulate the ingrowth and formation of bone. At twelve weeks, bone-bridging and ingrowth occurred uniformly in both the titanium fibermesh and the cobalt-chromium-molybdenum beaded prostheses. Maximum formation of osseous tissue over the implants occurred at two to four weeks. More bone formed in the posterior aspect of the prosthesis. At twelve weeks, 26 per cent of the porous space of the titanium fibermesh prosthesis and 47 per cent of the porous space of the cobalt-chromium-molybdenum beaded prosthesis were filled with bone. The torsional strength and stiffness of the prosthetic midsection that contained a conical coupling joint were increased significantly due to bone-bridging and ingrowth. The cortical bone that was apposed to the segmental prosthesis showed an increase in porosity. The use of bone cement did not appear to impede new-bone formation extracortically. The initial stability of the implant and the application of sufficient autogenous bone grafts are two important factors that contribute to the ultimate stable fixation of an implant by extracortical bone formation.     

Arterial false aneurysm after total hip arthroplasty. A case report

Vessel damage during implantation of a total hip arthroplasty is exceptional (0.2-0.3% incidence). We observed a case of false aneurysm of the common femoral artery diagnosed in a pauci-symptomatic patient seven months after total hip arthroplasty. The vessel was damaged by a fragment of cement in contact with the artery. Treatment consisted in extraction of the cement fragment and insertion of a vascular prosthesis after dissection and ligature of the pseudoaneurysm. A review of the literature of vascular complications after prosthetic hip surgery was undertaken. Early complications include acute bleeding or ischemia while late complications include pseudoaneurysm or arteriovenous fistulization. Predisposing factors are: infection, repeated contact between the implants and arterial walls, overly medial reaming of the acetabulum, intrapelvic cement spikes, and use of Hohmann retractor. We detail here the clinical signs, diagnostic approach, and natural course of arterial false aneurysm resulting from intra-pelvic cement leakage.     

A comparative study of porous coatings in a weight-bearing total hip-arthroplasty model

The purposes of this study were to compare ingrowth of bone into three types of porous coating and to determine the effect of the type of porous coating and the degree of coverage of the stem on the remodeling of bone on the femoral side in cementless hip arthroplasty. A left total hip arthroplasty was performed in forty dogs. Thirty of the dogs had a titanium-alloy femoral prosthesis that had had one of three types of commercially pure titanium porous material applied along the length of the anterior and posterior surfaces of the stem: ten with sintered fiber-metal, ten with sintered beads, and ten with plasma flame-spray coating. The remaining ten dogs had a femoral component that was circumferentially coated with commercially pure titanium that was plasma flame-sprayed along the length of the stem. In each group, five animals were killed at one month and five were killed at six months. Ingrowth of bone into all three types of porous coating was observed, indicating secure fixation of all components. By six months, there was more ingrowth of bone and new medullary bone adjacent to the proximal and distal aspects of the stems compared with the middle level of the stems in all groups. No significant difference in ingrowth of bone was observed in the beaded surface (25.2 per cent) and the fiber-metal surface (16.6 per cent) at one month, but at six months there was significantly less ingrowth into the beaded surface (23.3 per cent) than into the fiber-metal surface (37.3 per cent). In all groups, a proximal-to-distal gradient of loss of cortical bone was observed by six months. The group of dogs that had the stem with the circumferential coating experienced more severe loss of bone than did the three groups that had a stem with a partial coating. The magnitude of loss of bone was dependent on the extent rather than the type of porous coating.     

Preservation of the femoral neck in hip arthroplasty: results of a 13- to 17-year follow-up

In prosthetic surgery of the hip, it is important to remove only the pathological tissues, preserving as much as possible the osteo-articular architecture, in particular the femoral neck and the subchondral cencellous acetabulum. This allows the bone to easily adapt to the new biomechanical situation created by the prosthesis. Our long-term study of patients who underwent total hip replacement has confirmed such presuppositions. For this study, we used a biodynamic prosthesis, composed of a Lord hemispheric screwed cup with a biequatorial liner and an anatomical stem in Cr-Co-Md with a completely madreporic surface. This prosthesis is ideally configured to preserve the femoral neck. We followed 44 prostheses for 13–17 years. The clinical results were excellent or good in 82% of cases. Thigh pain, reported in only 14% of cases, spontaneously resolved. The mobility of the prosthetic hip and the consequent functional recovery were excellent, since conserving the neck re-stabilized the natural off-set, providing good equilibrium of the hip and the periarticular muscles. Radiographic analysis revealed survival of the femoral neck in approximately 80% of cases. The madreporic surface, when associated with correct positioning of an undersized stem, allowed for osteointegration with significant bone remodeling in the long term. Distal cortical hypertropy, found in 48% of cases, made it necessary to limit the madreporic surface finish to the stem's proximal two-thirds, leaving the distal one-third smooth. Received: 18 January 2000/Accepted: 18 February 2000