Test bed for assessment of the kinematical determination of navigation systems for total knee arthroplasty. Does a limited range of motion of the hip joint influence the accuracy of the determination?

OBJECTIVE: To locate the rotational center of the hip joint, CT-less navigation systems for artificial knee-joint replacement use movements of the femur with a rigid body attached. It cannot be assumed that the hip joint provides free mobility at all times. The purpose of the present study was: 1) To build a mechanical model to assess the system's accuracy in locating the rotational center of the hip by simulating a step-wise reduction of the range of motion (ROM) of the hip joint. 2) To determine the system's resolution by assessing a critical distance between two positions of the same femoral rigid body during the process of locating the rotational center of the hip. 3) To determine the sensitivity of the navigation system to the rotation of a femoral rigid body relative to the femoral bone while locating the rotational center of the hip joint. MATERIAL AND METHODS: To assess the impact that a limited ROM of the hip joint has on the accuracy of determination of the hip joint's rotational center, a test bed was built. This enables validation of the algorithm used by a CT-less navigation system. RESULTS: In the first part of the study, it was shown that a reduction of the ROM of the hip joint to 30% of its initial value had no evident influence on the accuracy of locating the rotational center of the joint. In the second part of the study, it was determined that the limit of resolution between two spatial points of the pivoting process is between 4.4 and 8.7 cm. The third part of the study showed that the examined system rejected the determination of the hip center even when the rigid body was only rotated through 22.5 degrees . CONCLUSIONS: The results show that osteoarthritis of the hip with a limited ROM, for example, cannot be taken as a contraindication for the use of the evaluated CT-less navigation system. However, the surgeon should ensure that the pivoting of the femur is performed without hindrance within the free range of motion of the hip joint. In accordance with the vendor's recommendation, a minimum distance of 10 cm should be maintained between two spatial points. To ensure safe and unconstrained operation, the rigid body must be firmly attached to the bone and must not be dislocated.     

Periacetabular osteotomy. Good pain relief in symptomatic hip dysplasia, 32 patients followed for 4 years

BACKGROUND: When surgical treatment of dysplastic hip osteoarthrosis is necessary, osteotomy is preferable to fusion or THR. We evaluated periacetabular osteotomy as a method of choice. PATIENTS AND METHODS: We treated 36 symptomatic dysplastic hip joints (32 patients) with the Bernese periacetabular osteotomy (PAO) between 1994 and 2001. We used the ilio-inguinal (I-I) approach in 32 hips and a modified Smith-Petersen (S-P) approach in 4. The patients were followed for mean 4 (1.5-8) years. In 1 patient with coxa valga, a varus femoral osteotomy was performed 1 year after PAO. 2 hips, in which we used the modified S-P approach, necessitated a capsulotomy. RESULTS: The median Merle d'Aubignè score increased from 13 points preoperatively to 16 points postoperatively. This improvement in terms of pain, motion and ambulation was accompanied by spatial reorientation and correction. The lateral center edge angle of Wiberg (CE) improved from an average of 7 degrees to 28 degrees. The anterior center edge angle of Lequesne (FP) improved from an average of 18 degrees to 28 degrees. The acetabular index angle (AC) improved from an average of 22 degrees to 10 degrees. Major complications included 1 partial lesion of the sciatic nerve, 1 malunion and 1 combined nonunion of the pubic and ischiatic osteotomy. 2 patients underwent subsequent total hip replacement (THR) for progressive osteoarthrosis with pain. INTERPRETATION: We found good radiographic correction of deformities, improvement of hip function and pain relief with an acceptable complication rate. With appropriate patient selection, this procedure is the most physiological treatment of symptomatic hip dysplasia in young adults. In addition to relieving symptoms, it may prevent and postpone the development of secondary osteoarthrosis.     

Metal-on-metal hip resurfacing: the effect of cup position and component size on range of motion to impingement

The aim of this dry bone study was to determine the range of hip motion to impingement for different hip resurfacing cup positions and component sizes. The maximum angles of hip flexion, extension, abduction, and adduction were calculated from 3-dimensional coordinates for: 1. Cup inclination of 30 degrees , 40 degrees , 50 degrees , 60 degrees , and 70 degrees with fixed anteversion; 2. Cup anteversion of 0 degrees , 10 degrees , 25 degrees , 35 degrees , and 45 degrees with fixed inclination; and 3. 3 different component sizes on the same size dry bones. An acetabular component inclination of 50 degrees and an anteversion of 25 degrees allowed the most physiologic range of hip motion. A larger-diameter femoral component relative to the native femoral neck diameter resulted in a greater range of hip motion to impingement.     

The effect of the orientation of the acetabular and femoral components on the range of motion of the hip at different head-neck ratios

BACKGROUND: Prosthetic impingement due to poor positioning can limit the range of motion of the hip after total hip arthroplasty. In this study, a computer model was used to determine the effects of the positions of the acetabular and femoral components and of varying head-neck ratios on impingement and range of motion. METHODS: A three-dimensional generic hip prosthesis with a hemispherical cup, a neck diameter of 12.25 millimeters, and a head size ranging from twenty-two to thirty-two millimeters was simulated on a computer. The maximum range of motion of the hip was measured, before the neck impinged on the liner of the cup, for acetabular abduction angles ranging from 35 to 55 degrees and acetabular and femoral anteversion ranging from 0 to 30 degrees. Stability of the hip was estimated as the maximum possible flexion coupled with 10 degrees of adduction and 10 degrees of internal rotation and also as the maximum possible extension coupled with 10 degrees of external rotation. The effects of prosthetic orientation on activities of daily living were analyzed as well. RESULTS: Acetabular abduction angles of less than 45 degrees decreased flexion and abduction of the hip, whereas higher angles decreased adduction and rotation. Femoral and acetabular anteversion increased flexion but decreased extension. Acetabular abduction angles of between 45 and 55 degrees permitted a better overall range of motion and stability when combined with appropriate acetabular and femoral anteversion. Lower head-neck ratios decreased the range of motion that was possible without prosthetic impingement. The addition of a modular sleeve that increased the diameter of the femoral neck by two millimeters decreased the range of motion by 1.5 to 8.5 degrees, depending on the direction of motion that was studied. CONCLUSIONS: There is a complex interplay between the angles of orientation of the femoral and acetabular components. Acetabular abduction angles between 45 and 55 degrees, when combined with appropriate acetabular and femoral anteversion, resulted in a maximum overall range of motion and stability with respect to prosthetic impingement. CLINICAL RELEVANCE: During total hip arthroplasty, acetabular abduction is often constrained by available bone coverage, while femoral anteversion may be dictated by the geometry of the femoral shaft. For each combination of acetabular abduction and femoral anteversion, there is an optimum range of acetabular anteversion that allows the potential for a maximum range of motion without prosthetic impingement after total hip arthroplasty. These data can be used intraoperatively to determine optimum position.     

Pelvic tracker effects on hip center accuracy using imageless navigation.

OBJECTIVE: Imageless computer assisted total knee surgical systems have commonly relied on determination of the functional rotational center of the femoral head as a landmark for determining the lower extremity mechanical axis. This has been accomplished through range of motion and center of rotation calculations for the femur with respect to the pelvis as the lower extremity is taken through a range of motion. Our study evaluated the use of this algorithm with and without a pelvic tracker attached to the iliac crest. MATERIALS AND METHODS: The functional center of the hip joint was also compared to the true radiographic center as determined by spiral CT data. Evaluating the different methods on six lower extremities from three whole-body cadavers revealed significant differences in the location of the calculated hip joint center, but little difference in the resulting lower extremity mechanical axis determination. The functional hip joint centers measured with and without a pelvic tracker differed from one another and from the CT-determined hip center. RESULTS: No differences were found in the coronal plane measurements, but statistically significant differences were found in the sagittal plane measurements. CONCLUSION: Algorithms that reduce the noise generated by pelvic movement should be devised to eliminate the need for a pelvic tracker.     

Early results of surgical treatment of dysplastic hip arthrosis with CDH prosthesis]

The paper presents the early results of surgical treatment of osteoarthritis secondary to hip dysplasia with CDH hip prosthesis. Between 2001 and 2002 fourteen cases of hip arthritis secondary to dysplasia were treated with CDH prosthesis. Surgery was performed in women, age ranging from 22 to 52 years (average age: 40 years). In 8 cases a cementless CDH femoral component was used. In all cases cementless Taperloc (Biomet) acetabulum components were used. Weight-bearing was allowed 7-14 days post-op. Final patient assessment was done 6-26 months post-op, using the Merle d'Aubigne classification. Patient satisfaction was also taken into account. Functional assessment using this classification yielded 7 points (range: 5-9 points) pre-op, and 11 points post-op (range: 10-12 points). In the post-op assessment, patients reported less pain and an increased range of motion of the hip. No infections were noted. In 1 case deep rein irritation was noted on the second day post-op. In 10 cases there was no limb length discrepancy post-op, while in 4 cases it ranged from 1.5 cm to 3.0 cm. CDH prosthesis allows secure hip replacement procedure, especially in cases with narrow femoral canals.     

Cementless hip arthroplasty in the treatment of patients with femoral head necrosis

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'Aubigné 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.     

The effect of femoral component head size on posterior dislocation of the artificial hip joint

BACKGROUND: Posterior dislocation continues to be a relatively common complication following total hip arthroplasty. In addition to technical and patient-associated factors, prosthetic features have also been shown to influence stability of the artificial hip joint. In this study, a dynamic model of the artificial hip joint was used to examine the influence of the size of the head of the femoral component on the range of motion prior to impingement and posterior dislocation following total hip replacement. METHODS: Six fresh cadaveric specimens were dissected, and an uncemented total hip prosthesis was implanted in each. Each specimen was mounted in a mechanical testing machine and loaded with use of a system of seven cables attached to the femur and pelvis that simulated the action of the major muscle groups crossing the hip joint. The hip was taken through a range of motion similar to that experienced when rising from a seated position. The three-dimensional position of the femur at the points of impingement and dislocation was recorded electronically. The range of joint motion was tested with prosthetic femoral heads of four different diameters (twenty-two, twenty-six, twenty-eight, and thirty-two millimeters). RESULTS: Significant associations were noted between the femoral head size and the degree of flexion at dislocation in ten (p = 0.001), twenty (p < 0.001), and thirty (p = 0.003) degrees of adduction. Increasing the femoral head size from twenty-two to twenty-eight millimeters increased the range of flexion by an average of 5.6 degrees prior to impingement and by an average of 7.6 degrees prior to posterior dislocation; however, increasing the head size from twenty-eight to thirty-two millimeters did not lead to more significant improvement in the range of joint motion. The site of impingement prior to dislocation varied with the size of the femoral head. With a twenty-two-millimeter head, impingement occurred between the neck of the femoral prosthesis and the acetabular liner, whereas with a thirty-two-millimeter head, impingement most frequently occurred between the osseous femur and the pelvis. CONCLUSIONS: With the particular prosthesis that was tested, increasing the diameter of the femoral head component increased the range of motion prior to impingement and dislocation, decreased the prevalence of prosthetic impingement, and increased the prevalence of osseous impingement. CLINICAL RELEVANCE: These results suggest that femoral heads with a twenty-eight-millimeter diameter increase the range of motion after total hip replacement. This may be beneficial when additional factors compromising joint stability are encountered.     

In vivo three-dimensional knee kinematics using a biplanar image-matching technique.

A biplanar image-matching technique was developed and applied to a study of normal knee kinematics in vivo under weightbearing conditions. Three-dimensional knee models of six volunteers were constructed using computed tomography. Projection images of the models were fitted onto anteroposterior and lateral radiographs of the knees at hyperextension and every 15 degrees from 0 degrees to 120 degrees flexion. Knee motion was reconstructed on the computer. The femur showed a medial pivoting motion relative to the tibia during knee flexion, and the average range of external rotation associated with flexion was 29.1 degrees . The center of the medial femoral condyle translated 3.8 mm anteriorly, whereas the center of the lateral femoral condyle translated 17.8 mm posteriorly. This rotational motion, with a medially offset center, could be interpreted as a screw home motion of the knee around the tibial knee axis and a posterior femoral rollback in the sagittal plane. However, the motion of the contact point differed from that of the center of the femoral condyle when the knee flexion angle was less than 30 degrees. Within this range, medial and lateral contact points translated posteriorly, and a posterior femoral rollback occurred. This biplanar image-matching technique is useful for investigating knee kinematics in vivo.     

Accuracy of determination of the hip centre in navigated total knee arthroplasty

AIM: In navigated knee arthroplasty the hip centre is determined by rotary motion of the femur (pivoting). The accuracy of this functional hip centre determination in vivo is unclear. In the following paper the accuracy of pivoting in the determination of the hip centre was examined. METHODS: Navigated (TC-PLUS, Solution, PLUS Orthopedics) total knee arthroplasty (PI Galileo, PLUS Orthopedics) was performed on 25 patients with primary arthritis of the knee joint. The position of the femoral component and the hip centre were postoperatively determined by computer tomography. Through comparison with the intraoperatively documented data, the deviation of the pivoted from the true hip centre in the frontal and sagittal planes was calculated. The degree of arthritis of the hip was determined on plain radiographs according to Kellgren. RESULTS: The mean deviation was determined to 1.0 +/- 0.7 degrees in the frontal plane and 2.5 +/- 1.6 degrees in the sagittal plane (p = 0.002). This corresponds to a mean overall deviation of 20 +/- 10 mm. The data were continuously, non-parametrically distributed without any outliers. A great range of motion (ROM) in the frontal as well as sagittal planes during pivoting resulted in a less accurate determination of the hip centre. There was no correlation to the degree of arthritis of the hip. CONCLUSION: The results indicate a recommendable ROM during pivoting for maximal accuracy of hip centre determination of 20 to 30 degrees in the sagittal plane and 30 to 40 degrees in the frontal plane. Arthritis of the hip is not a contraindication for functional determination of the hip centre.     

Periacetabular osteotomy for the treatment of acetabular dysplasia associated with major aspherical femoral head deformities

BACKGROUND: Acetabular dysplasia associated with deformity of the proximal part of the femur can result in hip dysfunction and degenerative arthritis in young adults. The optimal method of surgical correction for these challenging combined deformities remains controversial. METHODS: We retrospectively analyzed twenty-four hips in twenty patients who underwent a Bernese periacetabular osteotomy, which was done with a proximal femoral valgus-producing osteotomy in thirteen hips, for the treatment of acetabular dysplasia associated with proximal femoral structural abnormalities. The average age of the patients at the time of surgery was 22.7 years, and the average duration of clinical follow-up was 4.5 years. The Harris hip score and overall patient satisfaction with surgery were used to assess hip function and clinical results. Plain radiographs were used to assess the correction of the deformity, healing of the osteotomy, and progression of degenerative arthritis. RESULTS: The mean Harris hip score increased from 68.8 points preoperatively to 91.3 points at the time of the most recent follow-up (p<0.0001). Sixteen patients (nineteen hips) had an excellent clinical result, and one patient (one hip) had a good result. Two patients (two hips) had a fair result, and one patient (two hips) had a poor result. Twenty-two of the twenty-four hips improved clinically. There was an average improvement of 27.6 degrees in the lateral center-edge angle of Wiberg (p<0.0001), an average improvement of 33.1 degrees in the anterior center-edge angle of Lequesne and de Seze (p<0.0001), and an average improvement of 16.5 degrees in the acetabular roof obliquity (p<0.0001). The hip center was translated medially an average of 6.3 mm (p=0.0003). The T?nnis osteoarthritis grade was unchanged in twenty hips, progressed one grade in three hips, and progressed two grades in one hip. There were three major technical complications. At the time of the most recent follow-up, none of the hips had required total hip arthroplasty. CONCLUSIONS: The combination of acetabular dysplasia and proximal femoral deformities presents a complex reconstructive problem. The range of motion and radiographic assessment of the hip are major factors in the selection of patients for surgery. In selected patients, the periacetabular osteotomy combined with concurrent femoral procedures, when indicated, can provide comprehensive deformity correction and improved hip function.     

Inducible displacements of the cup and the femoral head during active range of motion: Dynamic RSA studies of cemented total hip replacements

We evaluated changes in position of the femoral head relative to the cup and of the cup relative to the pelvis in total hip replacement patients during hip motion 2 years postoperatively. Two patient groups with nine patients in each group were studied. Hip motions, translations of the femoral head center, and cup displacements were recorded with dynamic radiostereometric examination (RSA, 2 exposures/s) during abduction in Group 1 and with use of static RSA exposures at increasing flexion of the hip in Group 2. Conventional radiographic examinations were used to evaluate any radiolucent lines around the cups at 2 years. During active abduction the femoral head center moved medially (median 0.04 mm) and the cup tilted anteriorly (median 0.09 mm). Increments in radiolucent lines at 2 years correlated to medial femoral head penetration, posterior tilt, and retroversion of the cup at 20° of abduction. The extension of radiolucent lines at 2 years showed a positive correlation with proximal inducible displacement of the cup and posterior translation of the femoral head center at maximum hip flexion. Our observations may be of value in understanding the pathogenesis of the loosening process and may be used to facilitate the development of prosthetic designs that optimize hip kinematics. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1686–1693, 2013     

Radiographic analysis of low contact stress meniscal bearing total knee replacements

BACKGROUND: Meniscal bearing total knee replacements were developed to decrease the contact stresses on polyethylene and to reduce polyethylene wear. The kinematics of meniscal bearing knee replacements is poorly understood. The present study was designed to evaluate, with radiographic analyses, the motion of the meniscal bearings and the femoral rollback of the Low Contact Stress meniscal bearing knee replacement during knee flexion. METHODS: Eighty-one Low Contact Stress meniscal bearing total knee replacements in seventy-six male patients were assessed on fluoroscopically centered lateral radiographs made with the knee in full extension and in full flexion at an average of six years (range, twenty-four to 147 months) after the operation. The distance and direction of motion of the meniscal bearings and the center contact position of the femoral condyles were measured. Knee evaluations were performed with use of the Knee Society rating system. RESULTS: The average range of motion of the knees, measured on lateral radiographs, was 90 degrees (range, 45 degrees to 136 degrees). As they moved from terminal extension to terminal flexion, thirty-nine knees (48%) exhibited anterior motion of both bearings and sixteen (20%) demonstrated posterior motion of both bearings. Ten knees (12%) had reciprocal motion of the two bearings (one bearing moving anteriorly and one bearing moving posteriorly) with flexion, nine knees (11%) had motion of only one bearing, and seven knees (9%) had no motion of either bearing. When moving from full extension to full flexion, eighteen knees (22%) demonstrated femoral rollback, six knees (7%) showed no change in the position of femoral contact, and fifty-seven knees (70%) exhibited anterior sliding of the femoral condyles. Flexion of the knees demonstrating femoral rollback averaged 104 degrees (range, 76 degrees to 128 degrees), and flexion of the knees demonstrating anterior sliding averaged 94 degrees (range, 45 degrees to 125 degrees). The difference was significant (p = 0.03). According to the Knee Society rating system, the average clinical score for the entire group was 76 points (range, 27 to 100 points) and the average functional score for the entire group was 72 points (range, 30 to 100 points). The average clinical score was 79 points (range, 27 to 98 points) for the knees that exhibited anterior sliding of the femoral condyles and 87 points (range, 52 to 100 points) for those exhibiting femoral rollback (p = 0.09). The average functional scores were 64 points (range, 30 to 100 points) and 72 points (range, 45 to 100 points), respectively (p = 0.15). CONCLUSIONS: Radiographic analysis of meniscal bearing total knee replacements demonstrated an average anterior motion of both the medial and the lateral meniscal bearing of 4.7 mm (range, 1 to 14 mm) in thirty-nine knees (48%) as they moved from terminal extension to terminal flexion. Sixty-three knees (78%) demonstrated no femoral rollback as they were flexed. Knees with anterior sliding of the condyles had a significantly smaller average range of flexion (p = 0.03) and a lower average Knee Society score than did knees demonstrating femoral rollback. We believe that lack of rollback indicates a functional insufficiency of the posterior cruciate ligament.     

Mid- to long-term clinical findings in nailing of distal femoral fractures

The purpose of the study was to evaluate clinical long-term results after nailing of distal femoral fractures. The first 22 consecutive cases of distal femoral fractures in 22 patients (2 males and 20 females, age 65 years, range, 16-97 years) treated with retrograde femoral nailing from October 1994 to May 1997 are reported. Indications were AO 33 A1 (n = 7), 33 A2 (n = 2), 33 A3 (n = 3), and 33 C2 (n = 7) fractures. In 11 cases these were periprosthetic fractures of either total hip arthroplasty or hemiarthroplasty of the hip (five) or dynamic hip screw (six), four patients were polytraumatized, one patient had a floating-knee injury. No infections or thrombosis were observed postoperatively. In 17 cases primary union was achieved within 11 weeks (8-17 weeks); five patients died before consolidation. Patients returned to full weightbearing after 5 weeks (4-12 weeks); active knee motion ranged from 80 degrees to 130 degrees. In five patients slight malalignment < 10 degrees was radiographically assessed, with two showing incipient degenerative joint disease. Patients younger than 60 years returned to full preoperative activity level. Eleven patients surviving an average of 5.2 years (4.3-6.9 years) were available for long-term follow-up. As a subgroup they were evaluated according to the Leung score for distal femoral fractures with seven excellent and four good results and an average score of 84.3 points (70-92 points). The mid- to long-term results confirm retrograde femoral nailing to be a good alternative to plate osteosynthesis for AO 33 A- and C2-type fractures. In young patients (< 60 years) postoperative clinical performance was highly satisfying; however, the effects of postoperative hemarthros and anatomic malalignment on the cartilage surface remain major issues for further investigation.     

Primary metal-on-metal total hip arthroplasty with large-diameter femoral heads: a clinical trial of 59 hips

Large-diameter femoral heads with nearly anatomical sizes became available for metal-on-metal total hip arthroplasty after recent advances in metal-on-metal technology. We retrospectively studied the clinical and radiological results in 59 hips of 54 patients (32 women and 22 men, mean age 54.4 years) who underwent cementless metal-on-metal total hip arthroplasty with large-diameter heads. Patients were followed for a mean of 48.6 months. Range of motion improved significantly after surgery (p = 0.001). Harris hip scores improved from 38.5 points to 903 points at latest follow-up. We found no gender-related differences in Harris hip scores, whereas there was a correlation between age and Harris hip scores (p < 0.001), with excellent results being observed predominantly in younger patients. Mean acetabular inclination of the acetabular cup was 42.2 degrees (range: 37-51 degrees). Radiologically, a 1 mm thick radiolucency was detected in three acetabula, which were asymptomatic. One acetabulum was revised because of displacement. Three patients reported squeaking within their hips, which however disappeared in a short time. We did not observe any dislocation, deep infection or loosening. Grade 1 heterotopic ossification was detected in one hip. Although the inherent stability and the functional results of large anatomical heads are encouraging, longer follow-up data and larger series are essential to evaluate the real advantages of this type of prosthesis over conventional femoral heads.     

类风湿性关节炎继发严重髋臼内陷的全髋关节置换

目的探讨类风湿性关节炎继发严重髋臼内陷患者行全髋关节置换术治疗的临床疗效。 方法2011年1月至2014年11月,对解放军兰州总医院收治18例(20髋)类风湿性关节炎的严重髋臼内陷患者进行随访观察,其中男6例,女12例;年龄37～68岁,平均(46±8)岁。纳入病例均类风湿性关节炎继发严重髋臼内陷,髋臼内陷依Sotello-Garza和Charnley分型：Ⅰ型(内陷1～5 mm)0例,Ⅱ型(内陷6～15 mm)15例(17髋),Ⅲ型(内陷>15 mm)3例(3髋)。排除标准为先天性、创伤性或髋关节骨关节炎所继发的髋臼内陷。手术采用后外侧入路,股骨颈截骨后股骨头逆行取出,取自体松质颗粒骨打压植骨重建髋臼,采用压配方式植入生物型多孔髋臼假体。随访时采用Harris髋关节评分评估髋关节功能,X线平片观察假体是否有松动和再次内陷以及植骨愈合情况。对手术前、后髋关节功能、股骨头中心到Kohler线的距离等计量资料采用t检验分析。 结果手术时间为55～131 min,平均(89±8)min。失血量为165～480 ml,平均(295±11)ml。术中未发生血管、神经损伤以及髋臼和股骨劈裂骨折。随访时间2.5～6年,平均(4.5±1.7)年。术后X线片示4.5个月自体移植骨均与髋臼融合。末次随访的Harris髋关节评分由术前(55±9)分(40～65分)提高至(92±13)分(89～95分),差异有统计学意义(t ＝22.81,P <0.01)。股骨头中心到Kohler线的距离由置换前的(20± 4)mm增加到置换后的(21±3)mm,差异有统计学意义(t ＝2.312,P <0.01);随访期间均无髋臼假体松动发生。 结论类风湿性关节炎继发严重髋臼内陷的髋臼骨质菲薄且局部骨质疏松严重,髋臼形态不规则。采用自体股骨头颗粒骨移植填充髋臼结合生物型钽金属骨小梁髋臼杯假体,可恢复髋关节旋转中心并获得满意的近中期临床效果。     

精确匹配的半髋表面置换术治疗股骨头缺血性坏死

目的评价精确匹配的半髋表面置换术治疗股骨头缺血性坏死的疗效。方法回顾性分析41例(48髋)股骨头缺血性坏死患者的临床资料。其中男30例,女11例;年龄29～49岁,平均37岁。其中FicatⅢ期35髋,FicatⅣ期13髋,髋臼相对正常。41例患者(48髋)均采用金属半髋表面置换术。结果全部病例均获得随访,随访时间平均5.2年。平均UCLA髋关节功能评分明显改善(P=0.001),疼痛由术前的3.1分提高到9.1分;步行由4.4分提高到9.2分;活动由5.5分提高到7.1分。按UCLA评分标准,FicatⅢ期35髋术后的满意率为88.6%;FicatⅣ期13髋术后的满意率为69.2%(P=0.25)。8髋疗效差,UCLA髋关节功能评分无明显改善,术后X线检查发现7髋呈髋内翻植入了假体(插入的短柄与股骨轴线的夹角均小于130°)。假体的5年生存率为83.0%。结论在严格掌握手术适应证、提高手术技术的前提下,精确匹配的半髋表面置换术治疗股骨头缺血性坏死的疗效满意。     

Early experience and results with the periacetabular osteotomy. The Mayo Clinic experience.

The purpose of the present study was to review the early results of periacetabular osteotomy in the initial group of patients undergoing this procedure at the authors' institution. The first 21 hips in 19 patients with greater than 2 years followup, which represents the learning curve with this operation, were reviewed retrospectively. There were 14 females and five males with an average age of 21 years (range, 17-43 years). Intertrochanteric osteotomy was performed simultaneously on four patients with coxa valga and inadequate correction with periacetabular osteotomy alone. At an average of 38 months of followup (range, 24-52 months), the Mayo hip scores improved from an average of 46 points (range, 34-58 points) to an average of 68 points (range, 42-80 points). Hip range of motion declined slightly in all three arcs of motion. The lateral center edge angle of Wiberg improved from an average of 2 degrees to an average of 24 degrees. The loading zone angle (T?nnis) improved from an average of 24 degrees to an average of 11 degrees. The anterior center edge angle of Lequesne improved from an average of -6 degrees to an average of 38 degrees. Complications included two peroneal palsies, both of which resolved completely; three ischial fractures that healed uneventfully; three asymptomatic pubic nonunions; and asymptomatic heterotopic ossification in five patients. One patient underwent subsequent total hip arthroplasty for progressive arthritis and pain. Another patient required intertrochanteric osteotomy at a later date. The early results in this initial group of patients treated with periacetabular osteotomy show reliable radiographic correction of deformity and improved function with an acceptable complication rate. Patients should be counseled carefully about possible loss of motion postoperatively. Additional study is necessary to assess the long term results of this procedure.     

The effect of femoral rotation on the projected femoral neck-shaft angle

Femoral neck-shaft angle (NSA) was measured in a series of anteroposterior (AP) hip radiographs of a cadaveric femur in varying degrees of rotation. A mathematical model was developed to predict NSA on an AP radiograph in varying degrees of femoral rotation. The predictions of the model were found to correlate well with the experimental data (correlation coefficient = 0.94). Based on the mathematical model, a wide range of patient positioning was found to result in a <10 degrees error in the measurement of femoral NSA. Coxa vara, increased femoral anteversion, cerebral palsy, and developmental dislocation of the hip resulted in a more restricted range of acceptable femoral positioning. External rotation of the femur should be avoided during patient positioning because as little as 7 degrees can cause a > 10 degrees change in the apparent NSA. For all patient populations, internally rotating the femur will allow for determination of the femoral NSA to within 10 degrees .     

Coronal fractures of the femoral condyle: a brief report of five cases

Coronal fractures of the femoral condyle (Hoffa fractures) are uncommon injuries that have a better outcome when treated surgically. We report a series of five Hoffa fractures (including one nonunion) treated at a Level 1 trauma center by one surgeon employing a protocol of open reduction and internal fixation with lag screws through a formal parapatellar approach. Postoperatively, all patients began immediate unrestricted range of motion. Initial weight bearing was limited, but all patients were permitted full weight bearing by 10 weeks. All fractures healed within 12 weeks without complications. The final range of motion for the patients with acute fractures was at least 0 degrees to 115 degrees. The patient with a nonunion had a preoperative flexion contracture of 20 degrees and a final range of motion of 20 degrees to 125 degrees. Long-term follow-up (average 37 months, range 18-57 months) was available for 3 of the 5 patients, and Knee Society scores were calculated for these patients (average 173 of 200 points, range 160-180 points). The literature regarding the management of Hoffa fractures is reviewed.