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1.
Objective: To determine which of 3 different plate angles (20°, 25°, 30°) used in double pelvic osteotomy (DPO) would result in the most similar acetabular angle (AA) achieved with a 20° triple pelvic osteotomy (TPO) technique in dogs. Study Design: Experimental anatomic study. Animals: Cadaveric canine pelves (n=8). Methods: Transverse plane computed tomographic images of cadaveric pelves with intact sacroiliac joints, mounted in a custom jig, were made (baseline) and again after DPO (20°, 25°, 30°) and TPO (20°) and pelvic angles measured in 6 transverse planes. Pelvic angles of the 3 DPO techniques were compared with TPO using concordance correlation to determine which DPO angle resulted in an acetabular ventroversion angle closest to TPO. Results: Mean ± SD AAs were 32.89 ± 2.23 (baseline), 47.39 ± 4.39 (20° DPO), 51.43 ± 5.06 (25° DPO), 54.75 ± 4.38 (30° DPO), and 50.20 ± 5.76 (20° TPO). Concordance correlations for the AA compared with 20° TPO were 0.027 (baseline), 0.721 (20° DPO), 0.902 (25° DPO), and 0.593 (30° DPO). A concordance correlation of ≥0.8 indicates good correlation. Conclusions: A 25° DPO is most similar in acetabular ventroversion to 20° TPO (concordance correlation, 0.902).  相似文献   

2.
OBJECTIVE: To evaluate the effect of pubic symphysiodesis (PS) on pelvic development in skeletally immature dogs. STUDY DESIGN: Prospective randomized clinical trial. ANIMALS: Eight 4 month-old, sexually intact female Greyhounds. METHODS: Initial PS was performed at 4 months of age using a powered stapling device. Because of failure of the initial surgery, a second PS was performed 1 month later by resecting the pubic symphysis with a rongeur followed by placement of handmade bone staples in four dogs. Sham PS was performed in four control dogs at 4 months of age. Pubic growth rate and pelvic development were evaluated using standard plane radiography and computed tomography. Specific measurements included acetabular ventroversion, Norberg angle, lateral center-edge angle, and pelvic inlet dimensions. Hip distraction indices were determined as well. RESULTS: PS at 4 months of age using a stapling device failed. Pubic symphysiodesis using hand made staples was successful at 5 months of age and did not result in any clinically significant intraoperative or postoperative complications. Pubic symphysiodesis markedly decreased pubic symphysis growth in the treatment group. Hip distraction indices and pelvic inlet circumference, area, and width significantly decreased in treated dogs compared to those in the control group. Acetabular ventroversion was significantly increased in treated dogs compared to those in the control group. CONCLUSIONS: PS decreases pelvic canal size, increases acetabular ventroversion, and does not appear to have any clinically significant complications. CLINICAL RELEVANCE: PS performed in skeletally immature dogs with hip dysplasia may provide an effect similar to a triple pelvic osteotomy and warrants further investigation.  相似文献   

3.
OBJECTIVE: To determine the effect of osteotomy angle, reduction technique, and tibial plateau rotation angle on angular and rotational limb deformities. STUDY DESIGN: Geometric comparison using bone models. METHODS: Rotational osteotomies were made in the proximal metaphysis of artificial tibias at 0 degrees, 10 degrees, 20 degrees, -10 degrees, and -20 degrees from perpendicular with respect to either the proximodistal and craniocaudal tibial axes. Negative-numbered angles represented osteotomies made from distal to proximal or caudal to cranial. Changes in tibial angulation and torsion were measured using a 3-dimensional digitizing instrument at tibial plateau rotation angles from 0 degrees to 30 degrees at 5 degrees increments. Two osteotomy reduction techniques were used: complete osteotomy reduction and alignment of the medial cortex. The mean of 5 measurements of torsional and angular tibial deformity for each of the 9 osteotomy orientations in each reduction technique group was obtained. RESULTS: All had increasing angular and rotational deformity as tibial plateau rotation angle increased. In the medially aligned cortex group, all tibias had valgus deformity, and 8 of 9 tibias were internally rotated. In the reduced osteotomy group, minimal angular deformity was seen in tibias with osteotomy variation along the proximodistal axis; however, tibias with osteotomy variation along the craniocaudal axis had angular deformity ranging from 6.0 degrees of varus deformity to 14.3 degrees of valgus deformity. Rotational deformity was affected similarly by osteotomy variation along either axis. Reduction technique had greater affect on angular and rotational deformity than osteotomy angle variation. CLINICAL RELEVANCE: These results suggest that osteotomy reduction may play a greater role in angular and rotational deformity than osteotomy angle, although extreme osteotomy angles should be avoided. To decrease the severity of deformity, we recommend that the osteotomy be made perpendicular to the craniocaudal and proximodistal axes and be completely reduced with less regard for alignment of the medial cortex.  相似文献   

4.
Dysuria is a rare, but nevertheless severe postoperative complication associated with single-session bilateral triple pelvic osteotomy. Two cases are described in which contrast radiography of the lower urinary tract was used to diagnose urethral compression due to pelvic canal narrowing. Relief of the pressure on the urethra was achieved with an external fixation device, which distracted the acetabular fragments of the pelvis. In both cases the dysuria was resolved. The significance of this complication and its possible causes, especially regarding surgical technique, are discussed.  相似文献   

5.
Unilateral triple pelvic osteotomy was performed with three variations in technique on canine cadaver pelves. The following variables were studied: the angle of the ilial osteotomy (perpendicular to the long axis of the ilium and 10d?, 20d?, and 30d? off perpendicular); the degree of axial rotation (20d?, 30d?, and 45d?); and the type of fixation (canine pelvic osteotomy plate [CPOP] or a 2.7-mm dynamic compression plate [DCP]). Structural changes measured were the pelvic inlet and acetabular area, interischiatic tuberosity distance, and degree of acetabular version. Means and standard error of the means were determined for all pelvic measurements and were analyzed by three-way analysis of variance (P < .05). As the axial rotation increased from 20d? to 45d? an ilial osteotomy angled 10d?, 20d?, or 30d? resulted in a significantly greater decrease in the pelvic inlet area and significantly less deviation of the interischiatic tuberosity distance and degree of acetabular version from normal than an osteotomy directed perpendicular to the long axis of the ilium. Compared with the CPOP, as the axial rotation increased from 20d? to 45d?, the DCP resulted in a significantly greater decrease in the pelvic inlet area, an increase in the interischiatic tuberosity distance and degree of acetabular version, and less of an increase in the acetabular area. The results of this study suggest that to maximize dorsal acetabular coverage, while minimizing disruption of normal pelvic architecture, a CPOP and an ilial osteotomy angled 10d? to 30d? are preferred for all degrees of axial rotation.  相似文献   

6.
OBJECTIVE: To evaluate the influence of a tibial plateau leveling jig on osteotomy orientation, fragment reduction, and postoperative tibial plateau angle (TPA) during tibial plateau leveling osteotomy (TPLO). STUDY DESIGN: In vitro experimental study. ANIMALS: Large-breed canine cadavers (n=20). METHODS: TPLO was performed on 40 hindlimbs using 4 methods. Group 1: Jig; dogs in dorsal recumbency with the osteotomy parallel to the distal jig pin. Groups 2-4: No jig; dogs in lateral recumbency with the osteotomy in a vertical orientation (group 2: tibia parallel to the table top; group 3: controlled superimposition of the femoral condyles; group 4: internal rotation of the tibia). Postoperative TPA, fragment reduction, and osteotomy orientation relative to the tibial plateau were compared. Positive or negative values denoted deviation from parallel relative to the tibial plateau. RESULTS: Postoperative TPA, fragment reduction, and proximodistal osteotomy orientation were not significantly different between groups. Craniocaudal osteotomy orientation was significantly different (P<.005) from the tibial plateau. Median deviations were -4.0 degrees (group 1), 11.8 degrees (group 2), 11.2 degrees (group 3), and 0.2 degrees (group 4). Group 1 was not significantly different from group 4. CONCLUSIONS: A jig is not essential for osteotomy orientation, tibial plateau rotation, or fragment reduction. Comparable results were achieved performing a vertical osteotomy with the tibia slightly internally rotated (10 degrees -15 degrees) and parallel to the table surface. CLINICAL RELEVANCE: TPLO without use of a jig reduces surgical trauma, is less time consuming, and reduces cost.  相似文献   

7.
OBJECTIVE: To determine if screw loosening in triple pelvic osteotomies (TPO) is minimized when screws cranial to the ilial osteotomy had maximal sacral purchase. STUDY DESIGN: Prospective study. ANIMALS: Forty-six dogs with decreased acetabular coverage of the femoral head and minimal degenerative joint changes. METHODS: TPOs were performed where screws cranial to the ilial osteotomy were inserted to maximally engage sacral bone. Data collected were: use of ilial and ischial cerclage wire, screw length, ventrodorsal radiographic sacral width (most caudal aspect), pelvic canal diameter, and sacral penetration of the 3 cranial screws. On all subsequent radiographs, changes in screw position, pelvic canal diameter, and sacral purchase were noted. RESULTS: For 69 TPOs, 414 screws were used. Mean radiographic cranial screw length was 34.54 mm. Combined sacral depth of all 3 screws was 93.3% of sacral width. All osteotomies healed uneventfully. Twenty-four screws (6%) loosened with 12 being in the most cranial positions. Use of ischial or ilial cerclage wires did not statistically influence screw loosening. Pelvic diameter decreased by a mean of 7.79% from postoperative radiographs to the last radiographic recheck. CONCLUSIONS: By sufficiently engaging the sacrum with screws cranial to the ilial osteotomy, implant failures can be avoided and screw loosening minimized when a 6-hole TPO plate is used. CLINICAL RELEVANCE: To minimize screw-loosening in TPO, screws inserted cranial to the ilial osteotomy should be inserted to maximum sacral depth without penetrating the vertebral canal.  相似文献   

8.
OBJECTIVE: To assess the effect of rotating the acetabulum 20 degrees and 30 degrees on percent coverage (PC) of the femoral head by the acetabulum and Norberg angle (NA) after triple pelvic osteotomy (TPO). STUDY DESIGN: Retrospective study. ANIMAL POPULATION: Fifty-six client-owned dogs. METHODS: PC and NA were measured from preoperative, immediate postoperative, first recheck, and second recheck radiographs to compare the effects of 20 degrees and 30 degrees of rotation of the acetabulum after TPO for treatment of hip dysplasia. RESULTS: Within the 20 degrees rotation group, PC and NA values were significantly greater at each subsequent evaluation time starting at the preoperative measurement except for NA between the first and second recheck times. Within the 30 degrees rotation group, PC and NA values were significantly greater at each subsequent evaluation time starting at the preoperative measurement except for PC and NA between the first and second recheck times. No significant differences between the 20 degrees and 30 degrees rotation groups were found at any corresponding times for either PC or NA. CONCLUSIONS: Acetabular rotation of 20 degrees provided the same degree of improvement in acetabular femoral head coverage as 30 degrees of rotation after TPO at the immediate postoperative, first recheck, and second recheck evaluation times. CLINICAL RELEVANCE: Based on PC and NA, 20 degrees rotation of the acetabulum provides as much benefit as 30 degrees of acetabular rotation when performing a TPO.  相似文献   

9.
OBJECTIVE: To compare long-term outcomes of juvenile pubic symphysiodesis (JPS) and triple pelvic osteotomy (TPO) in dogs with hip dysplasia. DESIGN: Prospective clinical trial. ANIMALS: 18 dogs with hip dysplasia (ie, distraction index > or = 0.5 in at least 1 hip joint and no, mild, or moderate radiographic evidence of degenerative joint disease [DJD]). PROCEDURES: Dogs between 4 and 5.5 months old at enrollment were assigned to undergo JPS, and dogs between 5 and 12 months old were assigned to undergo TPO. All dogs were reexamined at 2 years of age. RESULTS: At 2 years of age, there were no significant differences between groups in regard to lameness scores, angle of extension of the hip joints, distraction index, peak vertical force, acetabular angle, radiographic DJD score, or owner-assigned scores of clinical function. Dorsal acetabular rim angle was significantly higher in dogs that underwent JPS than in dogs that underwent TPO. For dogs that underwent TPO, dorsal acetabular rim angle was significantly decreased and acetabular angle was significantly increased at 2 years of age, compared with values obtained prior to surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that JPS and TPO have similar effects on hip joint conformation in dogs with moderate to severe hip dysplasia but that neither procedure eliminates the hip joint laxity characteristic of hip dysplasia or the progression of degenerative changes.  相似文献   

10.
OBJECTIVE: To detect early screw loosening in triple pelvic osteotomy (TPO) and to evaluate the efficacy of retightening using fluoroscopic guidance and minimally invasive surgery to maintain acetabular alignment and achieve bone healing. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Sixteen dogs that had TPO. METHODS: Dogs (16) had TPO (21) by using pre-angled plates secured with 3.5 and 4.0 mm screws, with ischiatic or iliac cerclage, for osteosynthesis. In all but 1 TPO at least 1 screw was inserted into the sacral body (43 screws). The mean radiographic screw length inserted in the sacrum was 10.2 mm, and the mean percent sacral engagement was 22%. Dogs were examined clinically and radiographically immediately postoperatively, and at 10, 30, 60, and 90 days to evaluate screw position. Loose screws were retightened through stab incisions using fluoroscopy to locate the screw. RESULTS: TPO was performed without operative complications. At 10 days, 12 TPOs (57%; 11 dogs) had loose screws primarily located in the cranial aspect of the plate. This represented 20% (25) of the inserted screws. In 5 dogs, screw loosening resulted in medial rotation of the acetabular segment. All loose screws were retightened; 3 screws loosened again in 2 dogs and were detected at 60 days. However, the osteotomies healed with the planned acetabular rotation without further intervention. Screw tightening corrected the acetabular segment displacement. Screws correctly seated at 10 days did not subsequently loosen. Clinical and radiographic outcome was judged excellent in all dogs. CONCLUSION: Loose screws in TPO plates can be identified by 10 days postoperatively and retightened using fluoroscopic guidance to achieve acetabular realignment and healing without need for further surgery. CLINICAL RELEVANCE: Postoperative radiographic evaluation of screw position at 10 days after TPO is recommended to detect loose screws. Retightening loose screws should be considered as an alternative to TPO revision or confinement, especially in immature dogs.  相似文献   

11.
OBJECTIVE: To evaluate feasibility of single-session bilateral triple pelvic osteotomy with 8-hole iliac bone plates in dogs with bilateral hip dysplasia. DESIGN: Retrospective study. ANIMALS: 95 dogs with bilateral hip dysplasia. PROCEDURE: Medical records were reviewed, and information was obtained on signalment; body weight; angles of subluxation and reduction prior to surgery; durations of surgery and hospitalization; postoperative mobility; severity of lameness, radiographic grade of hip dysplasia, Norberg angle, and femoral head coverage before and after surgery; time required for radiographic evidence of iliac healing; change in pelvic diameter; implant integrity; and complications. RESULTS: Mean age at the time of surgery was 10.8 months, and mean weight was 35.2 kg (77.4 lb). Prior to surgery, mean angles of subluxation were 2.2 degrees on the right and 2.6 degrees on the left; mean angles of reduction were 25.9 degrees on the right and 27.3 degrees on the left. Mean surgical time was 95 minutes. All but 1 dog were able to walk on their own by the fourth day after surgery. Mean hospitalization time was 7.5 days. Clinical signs of lameness and radiographic grade of hip dysplasia were significantly improved during follow-up examinations. Mean time for radiographic iliac healing was 8 weeks. None of the plates and only 7 of the 1,520 (0.5%) screws loosened after surgery. Nineteen dogs had complications, but all complications were minor. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that single-session bilateral triple pelvic osteotomy with 8-hole iliac bone plates is effective for treatment of dogs with bilateral hip dysplasia.  相似文献   

12.
OBJECTIVE: To investigate factors influencing screw loosening after triple pelvic osteotomy (TPO) and ischial wire stabilization of the acetabular segment. DESIGN: Retrospective case series. Animals-227 dogs with congenital hip dysplasia or subluxated hip joints. PROCEDURES: Medical records and radiographs of 227 dogs that underwent 332 TPO procedures were evaluated, and data pertaining to screw type, plate position, sacral screw engagement, use of ischial interfragmentary wires, and pelvic alignment were assessed for associations with screw loosening. RESULTS: Complications developed in 96 of the 332 (29%) procedures. Cancellous screws without sacral engagement were associated with the lowest frequency (6%) of loosening, compared with cancellous and cortical screws engaging the sacrum and cortical screws that did not engage the sacrum. Frequency of screw loosening increased when cortical or cancellous screws engaged the sacrum and when cortical screws were used. In dogs that had surgery bilaterally, the first limb on which TPO was performed had a higher frequency of screw loosening than the second limb. Pelvic alignment loss was greatest (5.4 degrees ) when the 3 most cranial screws were loosened. Loss of pelvic alignment was significantly different between dogs that underwent surgery and had complications and those that underwent surgery and did not have complications in association with loosening of 1, 2, and 3 screws. CONCLUSIONS AND CLINICAL RELEVANCE: TPO screw loosening was multifactorial and related to stability of the affected ilium, screw type, and screw position. Placing cancellous screws that do not engage the sacrum in pelvic osteotomy plate positions 1 through 3 may decrease the number of screws that loosen.  相似文献   

13.
OBJECTIVE--To determine the long-term effects of juvenile pubic symphysiodesis (JPS) in dysplastic puppies. STUDY DESIGN--Prospective, randomized, clinical trial. ANIMALS--Seven dysplastic Chesapeake Bay retrievers and 2 beagle-crosses (BX1 and 2). METHODS--Five puppies had JPS performed with electrocauterization at 12, 16, 20, 22, and 24 weeks of age, respectively. Two puppies served as controls. BX1 and BX2 were used to obtain biopsies of the symphysis. Hips were evaluated for: pelvic development (transverse computerized tomography for acetabular angle [AA] and dorsal acetabular rim angle [DARA]); laxity [hip extended and stress radiography [distraction index (DI)]); Ortolani maneuver with reduction angles; acetabular coverage (Norberg angles); and function (coxofemoral range of motion, hip pain, and gait analysis by force-plate technique at 44 and 137 weeks of age). RESULTS--The pubis fused prematurely in every puppy that was operated on with the JPS technique. Greater acetabular responses were related to younger ages at surgery. The final mean AA in dogs that had JPS was 25 degrees greater than preoperative values; 40% increased over control. The DARA final mean was 10 degrees, 52% less than preoperative values and 46% less than control. The final mean DI in dogs having JPS was 0.28, 47% improved over preoperative values and 58% better than control. Mean pelvic dimensions in dogs that had JPS were 18% less than control. Gait analyses were normal for all dogs at 137 weeks. No urinary or bowel complications occurred. CONCLUSIONS--Significant ventrolateral acetabular rotation, increased hip coverage, diminished hip laxity, normal pain-free gait, and insignificantly reduced pelvic size occurred after JPS. CLINICAL SIGNIFICANCE--Dysplastic hips in young dogs were significantly improved by JPS.  相似文献   

14.
The ability of two canine pelvic osteotomy techniques to provide lateral rotation of the acetabulum was compared in vitro using an instrumented spatial linkage to measure acetabular displacement. Technique 1 was a double osteotomy and technique 2 was a triple osteotomy. We demonstrated that technique 1 provided more lateral rotation of the acetabulum. Both techniques provided a large amount of acetabular an-teversion. No relationship could be found between pelvic morphometry and final acetabular position. We concluded that the surgeon is the primary factor controlling final acetabular position.  相似文献   

15.
The effect of a triple pelvic osteotomy (TPO) procedure on the forces acting about the hip joint was examined in five dysplastic canine hips using a previously described theoretical analysis. Hip reaction force (Fh) and its angle of application (θh) were calculated from radiographic measurements made before and after TPO procedures which sequentially increased acetabular ventroversion from 0° to 20°, 30°, and 40°. The results of the in vitro study showed that Fh decreased with increasing acetabular ventroversion reaching an asymptotic value between 30° and 40°. The decrease in Fh corresponded to an increase in θh toward the vertical, with statistical significance found in both Fh and θh between 0° and 20°. The changes observed in Fh and θh after TPO were attributed to the medialization of the femoral head resulting from the reduction of the subluxated head. The results of this study suggest that the noted reduction in the magnitude of the forces acting on the hip joint may act in concert with increased coverage of the femoral head to effect the beneficial clinical results observed with the TPO procedure.  相似文献   

16.
OBJECTIVE: To identify risk factors for luxation after canine total hip replacement (THR). STUDY DESIGN: Retrospective study. SAMPLE POPULATION: 256 client-owned dogs that underwent THR. METHODS: Patient data surveyed included signalment, body weight, diagnosis, prior hip surgery, implant size, intraoperative complications, and angle of lateral opening of the acetabular component. RESULTS: Postoperative complications were recorded in 20 cases (7.8%). The most common complication was dorsal luxation which occurred in 12 dogs (4.7%). The interval between joint replacement and luxation ranged from 1 to 116 days (mean, 44 days). In 1 case, luxation was attributable to failure of the repair of an intraoperative fracture of the greater trochanter. Excluding this case, the mean angle of lateral opening in those dogs that sustained luxation was 62 degrees (range, 46 degrees - 75 degrees). The mean angle of lateral opening overall was 48 degrees (range, 18 degrees - 76 degrees). The angle of lateral opening was the only factor that had a statistically significant effect on whether luxation occurred (P = .035). Acetabular revision, performed primarily to reduce the angle of lateral opening, was performed in 8 dogs and successfully prevented subsequent luxation. CONCLUSION: Luxation of the prosthesis is substantially under the control of the surgeon. It is recommended that the acetabular cup be inserted at an angle of lateral opening of 35 degrees to 45 degrees. In those cases of THR luxation in which an inappropriate angle of lateral opening is identified, acetabular revision arthroplasty generally results in a good clinical outcome.  相似文献   

17.
A mature female domestic shorthaired cat with obstipation as a result of pelvic canal narrowing due to a pelvic fracture malunion was treated by triple pelvic osteotomy to widen the canal. The right hemipelvis was moved laterally and a modified bone plate was applied to the right ilium. A mild lick dermatitis occurred over the dorsum of the hind paw seven days postoperatively but resolved without treatment. The cat made an uneventful recovery without recurrence of the obstipation.  相似文献   

18.
A radiographic study was conducted to evaluate the effect of pelvic rotation and of simulated dorsal acetabular rim (DAR) remodeling on the radiographic appearance of the dorsal acetabular edge (DAE). The DAE is the line connecting the cranial and caudal rims of the acetabulum when viewing a pelvic radiograph made with the dog in the ventrodorsal position with the hind limbs extended. In this study, it was hypothesized that the DAE would change with pelvic rotation and simulated DAR damage. Ventrodorsal radiographs of eight canine pelves were made at 0 degrees, 5 degrees, and 10 degrees of left and right pelvic rotation over its longitudinal axis. These radiographs were repeated following removal of 2, 4, and then 6 mm of bone from the right DAR of each pelvis. The ratio of acetabular width to maximum depth of the DAE was calculated. The area between the DAE and a straight line connecting the cranial and caudal acetabular rims was measured digitally. The DAE depth and area changed with pelvic rotation, and with increasing simulated DAR damage. A linear relationship between the obturator foramina width ratio and pelvic rotation allowed estimation of the degree and direction of pelvic rotation. Equations were developed from the data to assist with the estimation of the amount of DAR remodeling on a clinical radiograph.  相似文献   

19.
Objective— Compare the biomechanical characteristics of screw and wire fixation with and without polymethylmethacrylate (PMMA) re-enforcement for acetabular osteotomy stabilization in dogs. Animals— Pelves removed from 8 adult mixed breed dogs weighing between 25 and 30 kg. Procedure— The pubic symphysis of each pelvis was split and a central transverse acetabular osteotomy was performed. One hemipelvis from each dog was stabilized with the composite fixation (interfragmentary Kirschner wire, two screws and a figure-of-eight orthopedic wire with PMMA). The contralateral hemipelves was stabilized with an interfragmentary Kirschner wire, two screws, and a figure-of-eight orthopedic wire without PMMA. All hemipelves were tested in bending by using a materials testing machine at a cross head speed of 5 mm/min. An extensometer was placed on the dorsomedial surface of the hemipelves centered over acetabular osteotomy to record distraction of the osteotomy during loading. A load/deformation curve and a load/distraction curve was produced for each hemipelvis. The slope for the initial linear portion of the load/deformation curve and the load/distraction curve, yield load and maximum load sustained were compared between repair groups using a paired t-test with P < .05 considered significant. Results— The slope of the load/deformation curve was significantly greater (P= .001 ) for hemipelves stabilized with the composite fixation (mean ± SD: 69 ± 18 N/mm) compared with hemipelves stabilized without PMMA (mean ± SD: 39 ± 8 N/mm). There was no significant difference (P= .593 ) between repair groups in the slope of the load/distraction curves as measured on the extensometer. Yield load was significantly greater (P= .0002 ) for hemipelves stabilized with the composite fixation (mean ± SD: 184 ± 25 N) compared to hemipelves stabilized without PMMA (mean ± SD: 74 ± 12 N). Maximum load sustained was also significantly greater (P= .013 ) for hemipelves stabilized with the composite fixation (mean ± SD: 396 ± 71 N) compared to hemipelves stabilized without PMMA (mean ± SD: 265 ± 94 N). Failure of hemipelves stabilized with the composite fixation occurred primarily by ventrolateral bending of the cranial and caudal pelvic segments at the osteotomy site. Failure of hemipelves stabilized without PMMA occurred by ventrolateral bending of the cranial and caudal pelvic segments at the osteotomy site with pronounced concurrent ventrolateral rotation of the cranial pelvic segment. Conclusion— PMMA improves the mechanical characteristics of acetabular fracture fixation, at least in part by neutralization of rotational forces. The results of this study justify use of PMMA as a component of the composite fixation when repairing acetabular fractures.  相似文献   

20.
OBJECTIVE: To describe the spatial orientation of the cemented acetabular component in cemented total hip arthroplasty, based on a ventrodorsal and lateral radiographic projection of the pelvis. METHODS: Equations were derived by using trigonometric relationships that describe the radiographic rotation about the longitudinal pelvic axis (alpha), transverse pelvic axis (beta), acetabular inclination (phi), acetabular inclination corrected for longitudinal pelvic rotation, version (phiC), acetabular version (theta), acetabular version corrected for longitudinal pelvic rotation (thetaC), acetabular inclination corrected for transverse pelvic rotation (phi(beta)), and acetabular version corrected for transverse pelvic rotation (theta(beta)) RESULTS: Alpha was calculated by using the equation alpha = sin(-1) (x/y) where x is the transverse distance between the dorsal spinous processes and the center of the pubis on a ventrodorsal radiograph and y is the distance from the pubis to the dorsal aspect of the first coccygeal vertebra perpendicular to the long axis of the pelvis on a lateral radiograph. Phi was calculated from the long axis (LA) and short axis (SA) of the ellipse formed by the radiopaque acetabular marker ring by using the equation phi = sin(-1) (SA/LA). phiC was calculated by using the equation phiC = phi +/- (alpha - tan(-1) (tan alpha cos thetaC)). Theta was determined as previously described. ThetaC was calculated by using the equation thetaC = tan(-1) (tan theta cos alpha). Theta(beta) and theta(beta) were calculated with the equations phi(beta) = tan(-1) (tan theta cos beta) and theta(beta) = theta - tan(-1) (sin beta), respectively. Beta could not be accurately determined from ventrodorsal and lateral pelvic radiographs. CONCLUSIONS AND CLINICAL RELEVANCE: These techniques allow for more accurate postoperative radiographic assessment of acetabular component positioning. This information can then be used in retrospective or prospective analyses examining that effects of implant positioning on clinical outcome.  相似文献   

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