Revision hip arthroplasty does not bring to the patient the same degree of benefit as the primary operation. We compared two hundred and thirteen patients undergoing revision arthroplasty with five hundred and forty-seven patients undergoing primary total hip replacement. The complication rate in the revision arthroplasty group was approximately twice as high in the primary group (p<
.05) primarily as a result of postoperative dislocation. Both groups of patients had a statistically significant improvement between their pre- and postoperative WOMAC and SF-36 physical scores; however, there was also a statistically significant difference in outcome when the two groups were compared, with primary patients having significantly improved WOMAC and SF-36 physical scores. To compare the outcomes between primary and revision total hip arthroplasty patients at one institution with regard to demographics, complication rates and functional outcome. Revision hip arthroplasty does not bring to the patient the same degree of benefit as does the primary operation. The reason for this is multi-factorial and includes a higher complication rate and lower functional outcome. Further study of the problems associated with revision total hip replacement especially focused on complication rates would appear to be warranted. All patients were entered prospectively in a database and were assessed by means of physical examination, radiographs, SF-36 and WOMAC questionnaires. Patients were followed for a minimum of two years with a range of two to five years. Patients were seen on an annual basis. Five hundred and forty-seven patients underwent primary total hip replacement and two hundred and thirteen patients underwent revision total hip replacement. 53.4% of patients undergoing primary and 52% of patients undergoing revision arthroplasty were female. Mean age at primary hip replacement 61.8 years, revision hip replacement 67.1 years. Post-operative complication rate was 7.6% in primary patients and 14.7% in revision patients (p<
.05); there was no statistically significant difference between the two groups with regard to intra-operative fracture, implant loosening or postoperative infection; there was a statistically significant difference in terms of dislocation with 0.8% of primary arthroplasties and 5.6% of revision patients sustaining at least one dislocation following their surgery (p<
.01). Both groups of patients had a statistically significant improvement between their pre- and post-operative WOMAC and SF-36 physical scores (p<
.0001); however, there was also a statistically significant difference in outcome when the two groups were compared with primary patients having significantly improved WOMAC scores (p<
.0001) and significantly improved SF-36 physical scores (p<
.0001).
The purpose of this study was to determine which activities are important to patients and to determine the severity of those problems. The five most important activities were walking outside, driving, walking indoors, stair climbing and daytime pain. Importance of these did not change postoperatively. The five most severe problems causing limitation were a limp, stiffness, loss of energy, daytime pain and locking. All these activities become statistically less severe over twenty-four months. Activities that are important to patients are different than the problems that are ranked by severity. Surgeons can educate patients that the severity of problems do improve over time following TKA. The objectives of this study were:
to determine the five most important activities and five most severe problems for patients prior to total knee arthroplasty (TKA) using the Patient Specific Index (PASI) and to determine the pattern of change in these activities over twenty-four months following TKA. Activities that are most important to patients are different than problems that patients find severe. Important activities remain important over time. Severe problems become less severe over time. Functional activities and PASI scores improve after TKA. Surgeons can educate patients that the problems they find most severe preoperatively do improve over time following TKA. Important activities remain important. Patients scheduled for elective primary (or revision) TKA at two tertiary care teaching hospitals were enrolled in the study, excluding those not fluent in English and those undergoing TKA for a tumour, acute fracture, or an infection of the prosthesis. Patients completed the PASI pre-operatively, six, twelve and twenty-four months post-operatively. One hundred and nineteen subjects were enrolled, nineteen were excluded. The five most important activities (ten- point scale, ten is most important) preoperatively were (mean; 95% CI): walking outside (6.25; 6.23–6.27), driving (6.17; 6.12–6.22), walking indoors (6.14; 6.12–6.16), climbing stairs (6.12; 6.10–6.14), and daytime pain (5.84; 5.81–5.87). These activities were not statistically less important over time. The most severe problems were limping (4.81; 4.77–4.85), stiffness (4.59; 4.56–4.62), lack of energy (4.51; 4.47–4.55), daytime pain (4.46; 4.43–3.39) and locking (4.38; 4.27–4.49). These were significantly less severe at twenty-four months (p <
.001).
1069 primary hip arthroplasty (THA) (416 males) and 1846 revision (798 males) patients were matched for sex, age and date of primary THA. Data were collected via retrospective chart review. Time to revision averaged 9.5 years. Revision THA patients were younger at primary THA (55 vs. 64 years), had a higher body mass index (27 vs. 30) and more frequently had a cemented acetabulum (p<
0.0001). After controlling for institution, earlier time to revision was predicted by younger age at primary THA, secondary OA or dysplasia, increased BMI, posterior surgical approach, cemented acetabulum, and small femoral head size (28 mm) (p<
0.05). To determine whether patient (age, gender, underlying disease, body mass index), surgical (surgical approach), and prosthetic (cemented vs. uncemented acetabular or femoral component, femoral head size) factors predict time to revision arthroplasty of primary total hip arthroplasty (THA). Patients who are younger when undergoing primary THA, have secondary osteoarthritis (OA) or dysplasia, are obese, and have a cemented acetabulum with a small femoral head by a posterior approach are at increased risk for revision THA. This study identified important, potentially modifiable patient, surgical and prosthetic factors that are adverse predictors of outcome. For the period 1980 to 2000, 1069 primary hip arthroplasty patients (416 males) and 1846 revision arthroplasty (798 males) patients were matched for sex, age and date of primary THA within two years. Revision THAs for infection were excluded. Data were collected via retrospective chart review. Time to revision THA averaged 9.5 years. In univariate analysis, patients who had revision THA were younger at primary THA (55 vs. 64 years, p<
0.0001), had a higher body mass index (BMI) (27 vs. 30, p<
0.0001), and more frequently had a cemented acetabulum (p<
0.0001). After primary THA, fewer patients who went on to revision arthroplasty had orthopaedic complications (6.5 vs. 16.5%). After controlling for institution, earlier time to revision was predicted by younger age at primary THA, underlying joint disease of secondary OA or dysplasia, increased BMI, posterior surgical approach, cemented acetabulum, and small femoral head size (28 mm) (multivariate Cox model, p<
0.05).
Thirty-eight patients with nonunion of the humeral shaft underwent a comprehensive assessment including completion of three patient-based functional outcome surveys as well as the determination of the Constant shoulder and Mayo elbow scores. Treatment consisted of compression plating with or without bone grafting. Smokers were found to have significantly longer time to union as compared to nonsmokers (25.1 weeks vs. 16.2 weeks, p<
0.001). Our results also demonstrated that increased time to union had a significant negative effect on the patient-reported functional outcome scores. To evaluate the functional outcome and identify prognostic factors that influence the healing time of surgically treated humeral shaft nonunions. Time to consolidation of operatively treated humeral shaft nonunions was significantly longer in smokers versus non-smokers. Time to union was negatively associated with the patient-reported functional outcome scores. The long-term functional outcome following surgical treatment of humeral shaft nonunions is dependent upon the time to consolidation. Smoking is a significant remediable risk factor for delayed union following surgical repair of humeral shaft nonunion. We identified thirty-eight patients (mean age fifty-five years) treated surgically for nonunion of the humeral shaft at a mean follow-up of sixty months. All patients underwent a comprehensive assessment including the completion of the SF-36, the DASH, the SMFA and the determination of the Constant shoulder and Mayo elbow scores. Seventeen (44.7%) patients were classified as ‘smokers’ and twenty-one (55.3%) were ‘non-smokers’. All nonunions united with a mean time of 16.2 weeks for non-smokers and 25.1 weeks for smokers (p<
0.001). Time to union was negatively associated with the Physical Function portion of the SF-36 (p=0.01), the DASH (p=0.01), and the Arm and Hand Function part of the SMFA (p=0.005). The only other factor that had a significant negative effect on the functional outcome scores was the presence of one or more comorbid factors (SF-36, p<
0.001; DASH, p<
0.001; SMFA, p<
0.001). Patient-oriented and surgeon based scores were found to correlate well (range r=0.545 to r=0.916, p<
0.001 for all combinations).
The purpose of this study was to evaluate functional outcome in patients with combined pelvic and acetabular fractures and to identify factors associated with outcome. One hundred and fifteen patients were identified. 63% were male; mean age was thirty-seven years; mean ISS was thirty. Three patients died from their injuries. At a mean follow-up of 3.5 years, patients exhibited profound functional deficits compared to the normal population. Those with an acetabular fracture involving the posterior wall or an associated lower extremity injury have a particularly poor prognosis. Combined pelvic and acetabular injuries are associated with high mortality and functional morbidity irrespective of treatment. To evaluate functional outcome in patients with combined pelvic and acetabular fractures and to identify factors associated with outcome. Combined pelvic and acetabular injuries are associated with high mortality and functional morbidity irrespective of treatment. These results will allow us to further investigate which injury is dictating prognosis in the combined injury – the pelvic or the acetabular fracture. One-hundred and fifteen patients with combined pelvic and acetabular injuries were identified at a level One trauma centre. 63% were male; mean age was thirty-seven years (13–88); mean ISS was thirty (16–75). Three patients died from their injuries. 16% involved bilateral pelvic fractures; 7% bilateral acetabular fractures; and for 2%, both were bilateral. 64% were Tile B and 34% were Tile C. Most acetabular fractures involved the anterior column or both column. Only 18% were treated with ORIF for both injuries. 25% had ORIF of their acetabulum and 14% had ORIF on their pelvis. Sixty-five patients completed validated functional outcome questionnaires at a mean follow-up of 3.5 (one to eleven) years. Patient function was significantly compromised with a mean MFA score of 33.8 (SD 21.8). Function was worse for all 8 SF-36 domains and the two component scores compared to the health status of the Canadian normal population (p<
0.001). Those individuals with an acetabular fracture involving the posterior wall or an associated lower extremity injury have a particularly poor prognosis. There was no relationship found between treatment or the pre-defined stability groups and functional outcome.
The purpose of this study was to determine the effect of cement mixing time on fixation augmentation in both healthy and simulated osteoporotic canine bone. In a canine diaphyseal model, screw insertion into liquid cement achieves greater bending stiffness and resists a greater load to failure than cement inserted as a paste. Bone cement in its liquid state may provide increased structural support in the setting of an osteoporotic fracture, possibly due to increased interdigitation of the cement with the screw threads and bone. An inconsistency exists among orthopaedic surgeons with regards to the appropriate mixing time for bone cement to achieve optimal results. The purpose of this study was to determine the effect of cement mixing time on fixation augmentation in both healthy and simulated osteoporotic canine bone. In a canine diaphyseal fracture model, screw insertion into liquid cement achieves greater bending stiffness and resists a greater load to failure than insertion into cement with the consistency of a paste. Bone cement in its liquid state may provide increased structural support in the setting of an osteoporotic fracture, possibly due to increased interdigitation of the cement with the screw threads and bone. Baseline stiffness for fourteen pairs of cadaveric canine femora was determined. A transverse diaphyseal osteotomy was created and fixed using an eight-hole DC plate and 3.5 mm screws. A 1cm gap was created at the osteotomy site simulating loss of bone. In the left femora, cement was mixed for one minute (liquid) prior to injection into pre-drilled holes; in the right femora, cement was mixed for five minutes prior to injection (thick paste). In each mixing time group, seven specimens were treated with a plate and properly sized pre-drilled and tapped holes (2.5mm), and seven received over-drilled holes (3.2 mm) to simulate osteoporotic bone. Four-point bending stiffness was determined for each plated construct, and normalized to baseline stiffness. Specimens were then loaded to failure. Within the properly sized holes, there were no statistically significant differences (SSD) in bending stiffness with or without a gap. The liquid cement had a force to failure 77% greater than that of cement as a paste (p<
0.05). Within the over-sized holes, there was no SSD between liquid and paste without a gap. With a gap, liquid cement demonstrated an increased bending stiffness of 24 % (p<
0.05) and force to failure was 92% higher (p<
0.05).
The purpose of this study was to determine the effect of positioning (lateral vs. supine) on pulmonary pathophysiology following pulmonary contusion and fat embolism in a canine model of polytrauma. Platelet and neutrophil activation were assessed using flow-cytometry. There were no significant differences between groups in CD62P and CD11/18 MCF (markers of platelet and neutrophil activation, respectively) following fat embolism. However, only animals in the lateral position displayed significant increases in both measures as compared to baseline values. Lateral positioning may exert an early effect on proinflammatory and coagulation activation, and may play a role in the development of acute lung injury. It has previously been suggested that acute lung injury can be influenced by patient positioning, be it lateral or supine. The purpose of this study was to determine the effect of positioning on pulmonary pathophysiology associated with concomitant pulmonary contusion and fat embolism in a canine model of polytrauma. Twelve dogs were randomly assigned to one of two surgical positioning groups, lateral and supine. The dogs were subjected to pulmonary contusion by application of force between 200–250 N/m2 for thirty seconds in three areas of one lung. Two hours later, fat embolism was induced via reaming of the ipsilateral femur and tibia and cemented nailing. Two hours later, the dogs were sacrificed. For flow-cytometric evaluation of platelet and neutrophil activation, venous blood samples were stained with fluorescence-conjugated antibodies against CD62P and CD11/18, respectively. There were no significant differences between the groups in CD62P and CD11/18 mean channel fluorescence (MCF) following pulmonary contusion and fat embolism. However, only animals in the lateral positioning group displayed significant increases in CD62P and CD11/18 MCF at two hours following fat embolism as compared to baseline values. Our findings suggest that lateral positioning, autoregulation and preferential blood flow to the contused non-dependent lung may render lung tissue more susceptible to congestion and lead to activation of both platelets and neutrophils. Lateral positioning may have an early effect on activation of the inflammatory and coagulation cascades and may be significant in the development of posttraumatic acute lung injury.
A cadaver study using six pairs of lower limbs was conducted to investigate the accuracy of computer navigation and standard instrumentation for the placement of the Birmingham Hip Resurfacing femoral component. The aim was to place all the femoral components with a stem-shaft angle of 135°. The mean stem-shaft angle obtained in the standard instrumentation group was 127.7° (120° to 132°), compared with 133.3° (131° to 139°) in the computer navigation group (p = 0.03). The scatter obtained with computer-assisted navigation was approximately half that found using the conventional jig. Computer navigation was more accurate and more consistent in its placement of the femoral component than standard instrumentation. We suggest that image-free computer-assisted navigation may have an application in aligning the femoral component during hip resurfacing.
This increased stiffness decreases motion under comparable loading conditions. In individuals who have excessive motion causing wrist symptoms, increasing the stiffness by capsular plication of the supporting ligaments decreases the motion to relieve symptoms. This technique has found success in clinical practice to relieve symptoms in patients with midcarpal instability.
Within the over-sized holes simulating osteoporotic bone, there was no difference between liquid and paste without a gap. With a gap, liquid cement demonstrated an increased bending stiffness of 24% (p<
0.05) and force to failure was 92% higher (p<
0.05). Bone cement in its liquid state may provide increased structural support in the setting of an osteoporotic fracture, possibly due to increased interdigitation of the cement with the screw threads and bone.
Twelve pairs of fresh-frozen, cadaveric femora were harvested. Each right femur was prepared for the cemented insertion of the femoral component of a total hip implant. Left femora served as matched intact controls. Following insertion of the implants, the distal tip of the stem was identified and an oblique osteotomy was made to represent a periprosthetic fracture. Proximally, plates were secured with cables and distally by bicortical screw fixation (c+s). The twelve pairs of femora were randomly divided into three groups: 1. Zimmer Cable-Ready System, 2. AO 4.5 mm broad, LC-DCP, with Wire Mounts and Double Luque Wires, 3. Dall-Miles Cable Grip System. Specimens were mounted and deforming forces were applied to test the biomechanical stiffness of the constructs. Following testing the plate-cable combinations, the proximal cables were removed and replaced with unicortical screws (s+s). Repeat testing was then performed as per the above protocol. The stiffness of the constructs relative to intact bone decreased (p<
0.05) with fixation utilising cables plus screws (c+s) during four-point bending (69–77%) and offset rotational loading (61–64%). When testing unicor-tical plus bicortical screw fixation (s+s) in these modes, a similar effect was seen. There was no difference between plate systems (ANOVA, p>
0.05). Comparisons of stiffness between cable plus screw combination versus unicor-tical plus bicortical screw combination revealed that the latter method of fixation (s+s) was more rigid (p<
0.05). Our study showed that the three plate-cable systems displayed similar biomechanical stiffness. In addition, when the cables were replaced proximally with unicortical screws, more rigid fixation was obtained in all but one plane of testing. We conclude that the method of plate stabilisation by screws or cables is more significant than the type of plate used for periprosthetic fracture stabilisation.
Two hundred and seventeen consecutive patients (238 hips) underwent total hip arthroplasty using the St Michael’s stem and a non-porous screw ring cup. Patients were followed prospectively clinically using the St Michael’s hip score and radiographically. At an average of 11.9 years (10-13.5 years), 55 patients (59 hips) had died, 23 patients (23 hips) were lost to follow-up. The St Michael’s hip score improved from 13.4 pre-operatively to 21.7 (out of a possible 25) at the latest follow-up. Thirty-seven (24%) of the acetabular components have been revised for aseptic loosening and an additional seven components are radiographically loose. No femoral components have been revised. Using Engh’s criteria one femoral component is definitely loose and two femoral components have stable fibrous ingrowth. Significant stress shielding was noticed in 23 hips (17%) without clinical consequences. Minor osteolysis was seen in 13 hips most commonly around the proximal femur and has not caused symptoms. The St Michael’s stem with its large pore size madreporic surface has comparable results to other porous coated stems with smaller pore size. The St Michael’s stem provided reliable ingrowth and fixation with an acceptable degree of stress shielding. The non-porous screw ring cup had a high failure rate.
We report a case of late dissociation of a one-piece metal-backed acetabular component, associated with a prolific soft-tissue reaction to the polyethylene debris. The polyethylene liner was not visible on the radiographs. The metal-backed shell could not be removed because of bone ingrowth. We recommend that modular systems be utilised in cementless arthroplasty of the hip and that radiographic markers be incorporated in the polyethylene of the acetabular cup.