The sphericity of the bearing surface in total hip arthroplasty

This study evaluated the sphericity of bearing surfaces in total hip arthroplasty. The out-of-roundness of metal femoral heads, the inner surface of polyethylene liners, and commercially available ball bearings was measured. The hip prostheses were obtained directly from the manufacturers. The sphericity of the bearing surfaces was significantly inferior to that of the ball bearings. The sphericity of the femoral head on the sagittal plane was inferior to that on the transverse plane. Several significant differences were found among different manufacturers. The sphericity of the femoral head on the sagittal plane and that of polyethylene significantly improved in 1999 and 2000 compared with those in 1995. Further improvement is desirable, however, because good sphericity is expected to prolong the functional performance of the prosthesis after total hip arthroplasty.     

生物型假体全髋置换术后早期负重近期效果

目的 探讨生物型全髋置换早期下床负重的可行性.方法 将56例年龄≤70岁的生物型假体全髋置换术后患者随机分成早期负重组(27例)和晚期负重组(29例),所有病例均采用小切口微创技术.早期负重组术后1周内下床拄拐自由负重,晚期负重组术后6周后下地负重,分别对两组进行术后6周和3、6、12、24个月的临床和影像学随访.髋关节功能按Harris评分,并对评分结果进行统计学分析.结果 术后6周、3个月的Harris评分早期负重组为(71.9±10.2)分、(87.6±9.4)分,晚期负重组为(60.3±9.1)分、(74.0±12.0)分,早期负重组明显高于晚期负重组(P＜0.01),Xx线最后随访时假体无松动、下沉;晚期负重组有2例患肢深静脉血栓形成.结论 在保证术中假体初始稳定性的前提下,生物型全髋置换术后可以早期下床负重;近期能明显促进患肢的功能恢复,预防下肢深静脉血栓形成.     

Alternative bearing surfaces in total hip arthroplasty

Polyethylene wear and extension of indications of total hip arthroplasty into younger and younger age groups have pushed manufacturers to develop more durable bearing surfaces. Standard polyethylene, the plastic used for the first 3 decades of hip replacement, virtually ceases to exist in its original form. Modifications of the processing, including sterlization in an inert environment and cross-linking, have demonstrated some improvements in wear. Hard-on-hard bearings such as ceramic-on-ceramic and metal-on-metal also have demonstrated extremely low wear. This article reviews the pros and cons of the alternative bearing options available to assist in the proper bearing selection for a particular patient.     

Catastrophic failure of ceramic-polyethylene bearing total hip arthroplasty

Complications of ceramic-polyethylene bearing total hip arthroplasty (THA) include osteolysis, loosening, dislocation, and component failure. Catastrophic acetabular component failure involves severe damage to both the polyethylene liner and metal shell. This case study presents the first reported complete wear-through of the acetabular portion of a ceramic-polyethylene arthroplasty presenting as a dislocation and a review of the literature. In this study, a patient's alumina ceramic femoral head penetrated the polyethylene liner and titanium shell and presented as a dislocated THA. The contributing factors for this catastrophic failure include young patient age, high activity level, thin polyethylene liner, backside wear, component positioning, polyethylene sterilization with gamma irradiation in air, and lack of appropriate follow-up. Revision THA was performed without complications.     

The effect of partial or full weight bearing ambulation after cementless total hip arthroplasty

The clinical and radiographic results of 46 patients who underwent 50 consecutive primary total hip arthroplasties using a fully porous-coated collared femoral component were determined at a minimum of 2 years' follow-up. Twenty-four patients (25 hips) who were allowed to bear full weight immediately postoperatively were compared with a historical control group of 24 patients (25 hips) who were instructed to bear < or =50 lb of weight for 6 weeks. The average Harris hip score for the partial weight bearing group was 95 compared with 97 for the full weight bearing group. All femoral components in both groups had radiographic evidence of bone ingrowth fixation at the final follow-up. When solid initial fixation is obtained intraoperatively and radiographically using a fully porous-coated (AML) femoral component, it seems that bone ingrowth fixation reliably occurs whether or not a partial or full weight-bearing postoperative protocol is followed.     

机器人辅助人工全髋关节置换的短期疗效分析

目的　探讨机器人辅助人工全髋关节置换术（total hip arthroplasty, THA）的短期疗效。方法　回顾性分析2018年8月至2019年3月于我科采用MAKO机器人系统辅助植入臼杯行THA手术治疗的79例（100髋）病人的临床资料,纳入机器人辅助组,并选择同一手术医师施行的80例（100髋）徒手THA病人纳入对照组,均采用标准髋关节后外侧入路。收集比较两组病人的围手术期相关信息,如手术时间、住院时间、髋臼杯位置、术后下肢长度差异（limb length discrepancy, LLD）、围手术期并发症及髋关节Harris评分（hip Harris score, HHS）。结果　病人术后均得到3个月以上随访,两组均未发生髋关节脱位、无菌性松动、假体周围感染或翻修。机器人辅助组的手术时间为（95.92±15.64） min,明显长于对照组的（83.12±18.22） min,两组比较,差异有统计学意义（t=3.309,P=0.001）。两组的术后HHS均较术前显著改善,但组间比较,差异无统计学意义（P＞0.05）。机器人辅助组的前倾角、外展角、LLD和偏心距差异分别为19.05°±5.03°、41.14°±3.66°、（2.87±3.75） mm、（3.34±1.79） mm,对照组分别为16.91°±5.48°、40.35°±6.57°、（4.23±3.12） mm、（3.98±2.04） mm;两组的前倾角和LLD比较,差异均有统计学意义（P均＜0.05）,但两组间的外展角和偏心距差异比较,差异无统计学意义（P＞0.05）。机器人辅助组的手术假体位于Lewinnek安全区内的比例更高（91% vs. 82%）,但两组间比较,差异无统计学意义（χ²=3.468,P=0.063）。结论　机器人辅助THA能够优化髋臼杯假体植入的精确性,不增加手术的并发症,但其远期效果仍需进一步研究证实。     

The effect of femoral component rotation on the five-year outcome of cemented mobile bearing total knee arthroplasty

Purpose

Performing total knee replacement, accurate alignment and neutral rotation of the femoral component are widely believed to be crucial for the ultimate success. Contrary to absolute bone referenced alignment, using a ligament balancing technique does not automatically rotate the femoral component parallel to the transepicondylar axis. In this context we established the hypothesis that rotational alignment of the femoral component parallel to the transepicondylar axis (0°?±?3°) results in better outcome than alignment outside of this range.

Methods

We analysed 204 primary cemented mobile bearing total knee replacements five?years postoperatively. Femoral component rotation was measured on axial radiographs using the condylar twist angle (CTA). Knee society score, range of motion as well as subjective rating documented outcome.

Results

In 96 knees the femoral component rotation was within the range 0?±?3° (neutral rotation group), and in 108 knees the five-year postoperative rotational alignment of the femoral component was outside of this range (outlier group). Postoperative CTA showed a mean of 2.8° (±3.4°) internal rotation (IR) with a range between 6° external rotation (ER) and 15° IR (CI 95). No difference with regard to subjective and objective outcome could be detected.

Conclusion

The present work shows that there is a large given natural variability in optimal rotational orientation, in this study between 6° ER and 15° IR, with numerous co-factors determining correct positioning of the femoral component. Further studies substantiating pre- and postoperative determinants are required to complete the understanding of resulting biomechanics in primary TKA.     

The effect of early weight bearing on migration pattern of the uncemented CLS stem in total hip arthroplasty

Forty-two patients (younger than 65 years) with osteoarthritis were operated on with an uncemented CLS stem and randomized to early unrestricted weight bearing combined with intensive physiotherapy or to partial weight bearing combined with self-training. Radiostereometric analysis showed 1.2 (+0.11 to -6.76) mm subsidence of the stem at 24 months in both groups. There was no significant difference in the migration pattern between the unrestricted and partial weight bearing groups. Actual loading on the operated leg, measured with the F-scan system, did not influence the migration of the stem. There was a strong correlation between the average subsidence at 3 and 24 months (r = 0.96). Early full weight bearing and active rehabilitation can be used for the uncemented CLS stem without increased risk of early loosening.     

巴曲亭应用于全髋关节置换术对手术出血的影响

目的探讨巴曲亭应用于全髋关节置换术(THA)对手术出血的影响。方法将62例行THA的患者随机分为治疗组(32例)与对照组(30例)。两组患者术前均使用低分子肝素抗凝治疗,治疗组巴曲亭2U溶于5 ml的生理盐水中,切皮前10 min静脉注射,术中磨削髋臼及扩髓使用2U巴曲亭溶于20 ml的生理盐水中局部喷洒于截骨面;对照组切皮前10 min注射同剂量的生理盐水,术中磨削髋臼及扩髓使用20 ml的生理盐水局部喷洒于截骨面。记录术中出血量、术后24 h引流量,检测术前及术后24 h凝血酶原时间(PT)、凝血酶时间(TT)、部分凝血活酶时间(APTT)、纤维蛋白原(FIB)等,术后第3天复查下肢深静脉血栓,记录患者住院时间。结果术中出血量:治疗组为(325.14±85.21)ml,明显低于对照组的(513.45±102.05)ml(P0.05)。术后24 h引流量:治疗组为(251.21±74.08)ml,明显低于对照组的(356.35±101.29)ml(P0.01)。两组患者术毕及术后24 h PT、TT、APTT均较术前有所延长,但治疗组差异无统计学意义(P0.05),对照组差异有统计学意义(P0.05)。两组术毕及术后24 h FIB均较术前下降,但治疗组差异无统计学意义(P0.05),对照组差异有统计学意义(P0.05)。术后第3天治疗组发生2例下肢深静脉血栓和1例深部血肿,对照组发生1例下肢深静脉血栓,两组均未发生切口感染。两组患者住院时间差异无统计学意义(P0.05)。结论巴曲亭应用于THA可以减少术中出血量及术后引流量,不影响患者的凝血效果,疗效确切,具有安全性。     

Revision total hip arthroplasty with metal on metal bearing for ceramic bearing fractures

BackgroundDue to concern of potential metallosis caused by residual microscopic ceramic particles, metal-on-metal (MoM) bearing is deemed undesirable in revision total hip arthroplasty (THA) for ceramic bearing fracture. We determined whether MoM bearing is suitable to be used in revision THA for ceramic fractures and also evaluated whether this treatment increases serum iron levels compared with MoM bearing revision THA for polyethylene failure.MethodsBetween 2006 and 2012, 22 patients underwent revision surgery using MoM bearing (28 mm femoral head in 18 hips and 32 mm in 4 hips) for ceramic bearing fracture and followed average 52.1 months. We assessed radiological parameter and functional outcome using Harris hip score (HHS) and WOMAC score. Also, serum cobalt (Co) and chromium (Cr) blood tests were performed and compared with the result obtained from age, sex- and follow-up duration-matched patients with MoM revision THA for failed polyethylene bearing.ResultsThe mean HHS improved from 60.6 preoperatively to 90.3 at final follow-up. There were no changes in cup position, progression of osteolytic lesions, and measurable wear of MoM bearing articulation at final follow-up radiographs. There was one case of recurrent dislocation after surgery, which was treated with greater trochanter distal advancement and one case of deep infection, which underwent two-stage revision. Mean serum Co level (1.7 vs. 1.4 μg/dl; p = 0.211) and Cr level (0.70 vs. 1.01 μg/dl; p = 0.327) showed no significant difference.ConclusionsMoM articulation with liner cementation into the acetabular cup along with total synovectomy can be chosen in revision surgery for ceramic fracture with good midterm follow-up. However, the use of MoM bearing is indicated when the stem and metal shell can be retained and ceramic on ceramic or ceramic on polyethylene bearing cannot be selected. Also long-term outcome needs to be further evaluated.     

Highly cross-linked polyethylene bearing surfaces in total hip arthroplasty

Polyethylene wear-induced osteolysis is the most significant primary factor limiting the life span of total joint arthroplasty. To reduce ultra-high-molecular-weight polyethylene (UHMWPE) particulate wear debris, highly cross-linked polyethylene (HXPE) bearings have been introduced in total hip arthroplasty (THA). In vitro hip simulator wear studies with HXPE have demonstrated a decrease in volumetric wear at the hip by 42% to 100% when compared with conventional metal-on-polyethylene bearings. Early to intermediate clinical results suggest that the in vivo wear properties of HXPE products are superior to those of conventional UHMWPE. Second-generation HXPE materials that utilize alternate cross-linking and free radical quenching techniques have been developed and propose to further minimize wear and oxidation.     

The effect of obesity on the outcome of hip and knee arthroplasty

The aim of this study was to evaluate the outcome of joint arthroplasty in obese and non-obese patients. We reviewed 2,026 consecutive primary total hip and 535 primary total knee arthroplasties performed for osteoarthritis. Patients were separated into two groups according to their body mass index (BMI): non-obese (BMI < 30) and obese (BMI ≥ 30). Their survivorships were compared. Case controlled studies were performed with 134 hip and 50 knee arthroplasties in obese patients. Each was matched individually with a control and their outcome compared. Log rank tests for equality of survival showed no difference in the survival for hip and knee arthroplasty at 11 and ten years, respectively. The obese group had significantly lower postoperative hip and knee scores at latest follow-up, especially in the range of motion. Overall patient satisfaction scores were comparable. There were no significant differences in the radiographic analysis of both hip and knee implants. Revision was used as an end point for the survival analysis. Functional scores (Harris hip score and Hospital for Special Surgery knee score), satisfaction for surgery and radiographic features were used as outcome measures for comparison. The mid-term survival of total hip and knee arthroplasty is not adversely affected by obesity. Despite lower clinical scores, the obese patients were satisfied with the results of their surgery and have an equivalent mid-term survival rate. It would be unreasonable to deny patients arthroplasty surgery purely on the basis of a BMI indicating obesity.     

Demographic factors affecting long-term outcome of total hip arthroplasty

We report the outcome of total hip arthroplasty (THA) in a cohort of patients with complete long-term radiographic and clinical followup information from our database of more than 48,000 primary hip replacements. The purpose of the study was to evaluate the influence of various demographic factors and patient comorbidity (Charnley classification) on the long-term outcome of THA. The cohort was comprised of 25,990 total hip replacements (THRs) in 10,243 (46.6%) men and 11,754 (53.4%) women with a median age of 66 years (range, 20-96 years) at the time of arthroplasty. Our study confirmed that THA has an impressive efficiency and reliability in alleviating pain and improving function for almost all of the patients. Furthermore, the results are enduring with more than 90% of patients being satisfied with the outcome at 15 years. Clinical outcome measures reach their maximum at 2 to 5 years after arthroplasty and thereafter they decline gradually. Furthermore, patient age, gender, body mass index, and main diagnosis all have an influence on specific functional parameters. The Charnley classification has the most profound effect on the overall functional status of patients.     

The effect of total hip arthroplasty surgical approach on gait.

This study examined the effect of the surgical approach used in total hip arthroplasty (THA) on gait mechanics six months following surgery. Quantitative gait analysis was performed on 29 subjects: 10 anterolateral (A-L) and 10 posterolateral (P-L) THA patients and nine able-bodied, velocity-matched subjects. Discriminant function analysis was used to determine the distinction of the groups with respect to sagittal plane hip range of motion, index of symmetry, trunk inclination, pelvic drop, hip abduction, and foot progression angles. The A-L group had the largest trunk inclination (3.0+/-2.4 degrees) and the smallest hip range of motion (34.0+/-7.4 degrees). Both THA groups demonstrated greater asymmetry as expressed by the smaller symmetry index (0.97+/-0.04 for A-L and 0.98+/-0.05 for the P-L) than the able-bodied group (0.99+/-0.01). The classification procedure correctly classified 89% of the control group cases, 90% of the A-L cases, and 50% of the P-L cases. These results support the conclusion that six months following surgery, the gait of the majority (85%) of THA patients has not returned to normal. The A-L patients displayed distinct gait patterns, while a small percentage (30%) of the P-L patients demonstrated normal gait. While these differences are statistically significant, the clinical significance is unknown and linked to the duration that they persist.     

Assessment of hip abductors by MRI after total hip arthroplasty and effect of fatty atrophy on functional outcome

Objectives

The aim of this study was to evaluate how fatty atrophy (FA) of the hip abductors in operated and non-operated hips affected the functional outcome following arthroplasty.

The value of patient activity level in the outcome of total hip arthroplasty

Commonly used total hip arthroplasty scores take into account pain, function, walking, and range of motion. The purpose of this study was to evaluate the value of patient activity level as part of the outcome of total hip arthroplasty. Using linear regression analysis, the relationship between patient activity level (University of California Los Angeles activity score), the Harris Hip Score, and the Short Form-12 health survey was evaluated in 152 patients (mean age, 58.7 years) with a mean follow-up 5.2 years (range, 2-21 years). The University of California Los Angeles activity scale had an R(2) value of 0.39 and 0.19 to the Short Form-12 physical and mental components, respectively, and 0.32 to the Harris Hip Score. By evaluating patient activity level, one obtains important qualitative information in assessing the clinical outcome after total hip arthroplasty.     

The infected hip after total hip arthroplasty

We studied the cases of fifty-two patients with an infection at the site of a prosthetic total hip replacement, and are reporting the significant clinical features, infecting organisms, methods of treatment, and results at long-term follow-up. Forty-eight per cent of the hips had had an operation prior to the index arthroplasty, and 42 per cent had a wound complication. All patients had pain in the infected hip, but only 54 per cent had an erythrocyte sedimentation rate of more than thirty millimeters per hour, 44 per cent had fever, and 15 per cent had leukocytosis. In 88 per cent of the patients a single organism was grown on culture, and Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli were present in about 75 per cent. When antibiotic therapy alone was the initial treatment, the infection was eradicated in only one patient. Excisional arthroplasty was the definitive surgical procedure in thirty-three patients and the infection was eradicated in twenty-seven of them, but the clinical result was satisfactory in only twenty. Of ten patients who had a true Girdlestone arthroplasty, none had recurrence of the infection and all had a clinically satisfactory outcome.     

Influence of preoperative functional status on outcome after total hip arthroplasty

BACKGROUND: International registries with large, heterogeneous patient populations provide excellent research opportunities for studying factors that influence treatment outcomes after total hip arthroplasty. In the present study, we used a European multinational database to investigate whether there is an association between three functional variables (preoperative pain, mobility, and motion) and functional outcome. METHODS: We performed a retrospective cohort study on preoperative and follow-up clinical data that were prospectively entered into the International Documentation and Evaluation System European hip registry between 1967 and 2002. The inclusion criteria for this study were an age of more than twenty years, an underlying diagnosis of osteoarthritis, and a Charnley class-A functional designation at the time of surgery. A total of 12,925 patients (13,766 total hip arthroplasties) who met these criteria were entered into the analysis. Three functional variables (pain, mobility, and motion) that were assessed preoperatively were evaluated postoperatively at various follow-up examinations for a maximum of ten years. RESULTS: Six thousand four hundred and one patients could walk longer than ten minutes preoperatively; of these, 57.1% had a walking capacity of more than sixty minutes at the time of the most recent follow-up. In comparison, 6896 patients had a preoperative walking capacity of less than ten minutes and only 38.9% of these patients could walk more than sixty minutes at the time of the most recent follow-up. The difference was significant (p < 0.01). Similarly, 10,375 patients had a preoperative hip flexion range of >70 degrees ; of these, 74.7% had a flexion range of >90 degrees at the time of the most recent follow-up. In comparison, 2793 patients had a preoperative hip flexion range of <70 degrees and only 62.6% of these patients had a flexion range of >90 degrees at the time of the most recent follow-up. The difference was also significant (p < 0.01). Lasting, complete, or almost complete pain relief was achieved by >80% of the patients following total hip arthroplasty regardless of their preoperative categorization of pain. CONCLUSIONS: Patients with poor preoperative walking capacity and hip flexion are less likely to achieve an optimal outcome with regard to walking and motion. In contrast, there is no correlation between the preoperative pain level and pain alleviation, which is generally good and long-lasting after total hip arthroplasty.