Total Hip Replacement in Ankylosing Spondylitis

Eighteen total hip replacements were performed in 10 patients with ankylosing spondylitis. The mean observation time was 3.8 years. Seven hips had been operated on before total hip replacement (THR): 6 were ankylotic before THR. The results as regards pain relief and increased walking distance were good. All hips improved in mobility after THR and this improvement was maintained during the observation time. Six of the 10 patients went back to full-time work. The differences between patients with ankylosing spondylitis and rheumatoid arthritis, as regards indications for and rehabilitation after THR, are discussed.     

Total hip replacement in ankylosing spondylitis

Eighteen total hip replacements were performed in 10 patients with ankylosing spondylitis. The mean observation time was 3.8 years. Seven hips had been operated on before total hip replacement (THR); 6 Were ankylotic before THR. The results as regards pain relief and increased walking distance were good. All hips improved in mobility after THR and this improvement was maintained during the observation time. Six of the 10 patients went back to full-time work. The differences between patients with ankylosing spondylitis and rheumatoid arthritis, as regards indications for and rehabilitation after THR, are discussed.     

Increased risk of revision for infection in rheumatoid arthritis patients with total hip replacements

Background and purpose — Medical treatment of rheumatoid arthritis (RA) has changed dramatically over the last 15 years, including immune modulation. We investigated the risk of revision for infection after primary total hip replacement (THR) in patients with rheumatoid arthritis over a 16-year period, and compared it with that in THR patients with osteoarthritis (OA).

Patients and methods — We identified 13,384 THRs in RA patients and 377,287 THRs in OA patients from 1995 through 2010 in a dataset from the Nordic Arthroplasty Register Association (NARA). Kaplan-Meier survival curves, with revision for infection as the endpoint, were constructed. Cox regression analyses were performed to calculate the relative risk (RR) of revision for infection adjusted for age, sex, fixation technique, and year of primary surgery.

Results — RA patients had a 1.3 times (95% CI 1.0–1.6) higher risk of revision for infection. After 2001, this risk increased more for RA patients than for OA patients. During the first 3 months and from 8 years postoperatively, the risk of revision for infection was higher in RA patients with THRs fixated with antibiotic-loaded cement than in corresponding OA patients.

Interpretation — We found a slightly higher overall risk of revision for infection in RA patients than in OA patients, but this difference was only present after 2001. In THRs with antibiotic-loaded cement, the risk of very early and late infections leading to revision was higher in RA patients than in OA patients.     

Mid-term functional and radiological outcomes after total hip replacement performed for complications of acetabular fractures

ObjectiveAcetabular fractures can lead to serious complications such as avascular necrosis of the femoral head (AVN), osteoarthritis, non-union. Total hip replacement (THR) is a treatment option for these complications. The purpose of this study was to assess the functional and radiological outcomes of THR at least 5 years after the primary implantation.MethodsThis retrospective study analysed clinical data from 77 patients (59 males, 18 females) who were treated from 2001 to 2022. Data was collected on the incidence of AVN of the femoral head, complications, interval from fracture to THR, reimplantation. The modified Harris Hip Score (MHHS) was used to evaluate outcome.ResultsThe mean age at the time of fracture was 48 years. Avascular necrosis developed in 56 patients (73%), with 3 cases of non-union. Osteoarthritis without AVN developed in 20 patients (26%), non-union without AVN in one patient (1%). The mean time from fracture to THR was 24 months for AVN with non-union, 23 months for AVN alone, 22 months for AVN with arthritis, 49 months for hip osteoarthritis without AVN. The time interval was significantly shorter for cases of AVN than for cases of osteoarthritis without AVN (p = 0.0074). Type C1 acetabular fracture was found to be a risk factor for femoral head AVN (p = 0.0053). Common complications of acetabular fractures included post-traumatic sciatic nerve paresis (17%), deep venous thrombosis (4%), infections (4%). Hip dislocation was the most common complication of THR (17%). There were no cases of thrombosis following THR. According to Kaplan-Meier analysis, the proportion of patients without revision surgery within 10-year period was 87.4% (95% CI 86.7–88.1). The results of the MHHS after THR: 59.3% of patients had excellent results, 7.4% good, 9.3% satisfactory results, and 24.0% had poor results. The mean MHHS was 84 points (95% CI 78.5–89.5). Paraarticular ossifications were observed in 69.4% of patients in the radiological evaluation.ConclusionTotal hip replacement is an effective treatment for serious complications of acetabular fracture treatment. Its results are comparable to THR peformed for other indications, although it is associated with a higher number of paraarticular ossifications. Type C1 acetabular fracture was found to be a significant risk factor for early femoral head AVN.     

Internal fixation compared with total hip replacement for displaced femoral neck fractures in the elderly. A randomised,controlled trial

The treatment algorithms for displaced fractures of the femoral neck need to be improved if we are to reduce the need for secondary surgery. We have studied 102 patients of mean age 80 years, with an acute displaced fracture of the femoral neck. They were randomly placed into two groups, treated either by internal fixation (IF) with two cannulated screws or total hip replacement (THR). None showed severe cognitive dysfunction, all were able to walk independently, and all lived in their own home. They were reviewed at four, 12 and 24 months after surgery. Outcome measurements included hip complications, revision surgery, hip function according to Charnley and the health-related quality of life (HRQoL) according to EuroQol (EQ-5D). The failure rate after 24 months was higher in the IF group than in the THR group with regard to hip complications (36% and 4%, respectively; p < 0.001), and the number of revision procedures (42% and 4%, p < 0.001). Hip function was significantly better in the THR group at all follow-up reviews regarding pain (p < 0.005), movement (p < 0.05 except at 4 months) and walking (p < 0.05). The reduction in HRQoL (EQ-5D index score) was also significantly lower in the THR group than in the IF group, comparing the pre-fracture situation with that at all follow-up reviews (p < 0.05). The results of our study strongly suggest that THR provides a better outcome than IF for elderly, relatively healthy, lucid patients with a displaced fracture of the femoral neck.     

Neonatal hip instability and risk of total hip replacement in young adulthood

Background and purpose Dysplasia is probably the most common underlying condition in osteoarthritis of the hip, leading to total hip replacement (THR) in young adulthood. We investigated whether hip instability at birth predisposes to THR in young adulthood.

Methods Since 1967, all newborns in Norway have been screened for neonatal hip instability (NHI) and the results have been reported to the Medical Birth Registry of Norway (MBRN). In the period 1967-2004,2,218,596 newborns were registered. From 1987 to 2004, 442 of these individuals had been reported to the Norwegian Arthroplasty Register (NAR) after undergoing total hip replacement (mean age 25 (12-36) years).

Results Neonatal hip instability was reported in 19,432 newborns (0.88%) in the MBRN; according to the NAR, they had a 2.6 (CI 1.4-4.8) times increased risk of THR in young adulthood compared to those without NHI. The absolute risk was low, however; only 57 (95% CI: 30-105) in 10⁵ for patients with NHI compared to 20 (95% CI: 18-22) in 10⁵ for those without registered hip pathology. Of the 442 patients with THR, 95 were operated because of osteoarthritis of the hip secondary to dysplasia, according to the surgeon's report. However, only 8 of these 95 patients had been reported to have hip instability at birth.

Interpretation Neonatal hip instability increases the risk of THR in young adulthood. Unexpectedly, only 8% of those who underwent THR due to dysplasia were reported to have unstable hips at birth. Our results indicate that clinical testing for NHI is insufficient as a screening method for dysplastic hips that require THR in young adulthood.     

Endoprothetischer Hüftgelenkersatz bei zerebralparetischen Patienten

BACKGROUND: The treatment of painful osteoarthritis of the hip in cerebral palsy requires a therapy concept that considers the pathoanatomical features and adapts the treatment to the individual physical and mental abilities. Femoral head resection has been proven be effective in severely dislocated hip joints in completely immobilized patients, whereas no satisfactory outcome is achieved in those patients with sufficient walking ability and moderate expression of spasticity. RESULTS: The following study investigates the results of total hip replacement (THR) in patients with tetraspastic cerebral palsy. Between 1992 and 2004, 19 total hip arthroplasties were performed in 175 patients with an average follow-up of 4,6 years. In all patients the walking ability improved significantly; 84% of the patients were pain free. Aseptic loosening of the femoral component was registered in one patient. A periprosthetic fracture in another patient required the implantation of a modular non-cemented femoral component. CONCLUSION: In this study total hip arthroplasty represents an important expansion of operative treatment options in secondary osteoarthritis of cerebral palsy in selected and cooperative patients. Taking the contradictions into consideration (severe athetosis, absence of adequate weight bearing, severe pelvic obliquity), THR promises to be an effective alternative to femoral head resection with significant pain reduction and improvement of walking abilities.     

人工关节置换治疗高龄重度骨质疏松性股骨粗隆间骨折的中期疗效随访

目的：观察人工髋关节置换治疗高龄重度骨质疏松性股骨粗隆间骨折病人的中期临床疗效。方法对2008年1月至2011年5月收治的71例高龄重度骨质疏松性股骨粗隆间骨折患者采用人工髋关节置换术,并随访其疗效。结果本组71例（72髋）,其中2例（2髋）采用全髋关节置换,69例（70髋）采用人工双动股骨头置换;年龄80～89岁,平均85.5岁。无一例术中休克或死亡。术后均在2～3 d下床活动,无肺炎、褥疮等并发症发生。随访时间11～72个月,平均47.7个月,术后死亡15例：术后1年内有7例;术后第2年有4例;术后第3年有3例;术后第4年有1例,其余病例均骨折愈合良好,未发生假体下沉、松动现象,术后行走功能恢复正常（术后Harris评分平均84.5分）。结论人工关节置换治疗高龄重度骨质疏松性股骨粗隆间骨折,可早期下地功能锻炼,减少卧床时间及并发症的发生,有利于早期功能恢复,但应严格掌握手术指征,远期疗效则需要进一步观察。     

Total hip replacement after failed hemiarthroplasty

A retrospective follow-up study comprising 37 patients operated upon using total hip replacement (THR) following failed hemiarthroplasty (HA) is reported. The mean duration time after HA was 83 months. Twenty-four patients showed satisfactory results at a mean follow-up of 4.8 years, while 13 patients found the results unsatisfying from the very beginning. The mean (SD) observation time after THR was 50 (38) months. The mean (SD) age of 28 women and 9 men examined at the follow-up was 69 (10) years. The mean Mayo/Harris hip scores were 76/76 (range 41-98) points. The final results were excellent in nine, good in ten, fair in five and poor in thirteen cases. After complicated subcapital femoral fractures treated by HA, the final result after THR was excellent or good in four, fair in three and poor in seven cases. However, revision arthroplasty was performed in two cases, in the one because of loosening, in the other due to recurrent dislocation. Radiologically, at follow-up in 13 patients, 11 femoral and 6 acetabular components showed signs of loosening. In conclusion, THR can be recommended as primary operation for the treatment of acute subcapital femoral fractures in elderly and active patients.     

High patient satisfaction in 445 patients who underwent fast-track hip or knee replacement

Background and purpose — Patient satisfaction is important in fast-track total hip and knee replacement (THR, TKR). We assessed: (1) how satisfied patients were with the treatment; (2) factors related to overall satisfaction; and (3) whether there was a difference between THR and TKR regarding length of stay (LOS) and patient satisfaction.

Patients and methods — In this follow-up study, a consecutive series of 445 patients undergoing THR and TKR completed a questionnaire 2 weeks after discharge. LOS and short-term patient satisfaction with the fast-track management were measured. Patient satisfaction was measured using a numerical rating scale (NRS; 0–10).

Results — For THR, the median satisfaction score was 9–10 and for TKR it was 8.5–10 in all parameters. Older THR patients had higher overall satisfaction. No association was found between overall satisfaction following THR or TKR and sex comorbidity, or LOS. THR patients had shorter mean LOS than TKR patients, even though the median LOS was 2 days for both groups. THR patients were more satisfied than TKR patients in the first weeks after discharge.

Interpretation — Patient satisfaction is high following fast-track THR and TKR, with scores ranging from 8.5 to 10 on the NRS. A qualitative investigation of the first weeks after discharge is required to learn more about how to improve the experience of recovery.     

Total hip replacement with a collarless polished cemented anatomic stem: clinical and gait analysis results at ten years follow-up

Purpose

The aim of this study was to determine outcomes of total hip replacement (THR) with the Lemania cemented femoral stem.

Methods

A total of 78 THR patients were followed and compared to 17 “fit”, healthy, elderly and 72 “frail” elderly subjects without THR, using clinical outcome measures and a portable, in-field gait analysis device at five and ten years follow-up.

Results

Forty-one patients (53 %), mean age 83.4 years, available at ten years follow-up, reported very good to excellent satisfaction. Mean Harris Hip and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were 81.2 and 10.5 points, respectively, with excellent radiological preservation of proximal femur bone stock. Spatial and temporal gait parameters were close to the fit group and better than the frail group.

Conclusions

Lemania THR demonstrated very good, stable clinical and radiological results at ten years in an older patient group, comparable to other cemented systems for primary THR. Gait analysis confirmed good walking performance in a real-life environment.     

Total hip replacement with spongious bone graft for acetabular protrusion in patients with rheumatoid arthritis

Total hip replacement (THR) with the use of autogenous spongious bone graft reinforcement to the medial acetabular wall proved a successful surgical procedure in patients with rheumatoid arthritis and acetabular protrusion.

In 25/26 THR followed for an average of 2 (1–4) years, the bone grafts healed in place radiographically and no further protrusion occurred. A non-progressive radiolucent zone of 3 mm at the bone-cement interface occurred around one acetabular cup. Recurrent dislocations occurred in one hip, which eventually turned out to have a loose acetabular cup. One hip with a firmly seated cup was converted to a resection arthroplasty 4 months after the primary operation because of deep infection.     

Reverse hybrid and cemented hip replacement compared using radiostereometry and dual-energy X-ray absorptiometry

Background and purpose Total hip replacement (THR) with a reverse hybrid (RH), a combination of a cemented polyethylene cup and a cementless femoral stem, has been increasingly used in Scandinavia. In a randomized trial, we compared an RH THR with a proximal hydroxyapatite- (HA-) coated stem to a conventional cemented THR. Both groups received the same polyethylene cup.

Patients and methods 51 patients (52 hips) were included. Radiostereometry (RSA) and dual-energy X-ray absorptiometry (DEXA) were performed postoperatively and after 6, 12, and 24 months. 42 patients (43 hips) were followed for 2 years.

Results Mean cup rotation around the x-axis was 0.13° for the cemented group and –0.24° for the RH group (p = 0.03). Cup migration in the other axes, and stem migration and wear were similar between the 2 study groups. Bone remodeling around the cup was also similar between the groups. Bone loss in Gruen zone 1 was 18% for the cementless stems, as compared to an increase of 1.4% for the cemented ones (p < 0.001). Bone loss was similar in the other Gruen zones. Harris hip score and Oxford hip score were similar pre- and postoperatively in the 2 groups.

Interpretation In the present study, RH THR with a cementless hydroxyapatite-coated stem and conventional cemented THR did not show any major differences regarding stem migration and bone loss after 2 years of follow-up.     

Standardized incidence rates of total hip replacement for primary hip osteoarthritis in the 5 Nordic countries: similarities and differences

Background?The national hip registers of the Nordic countries provide an opportunity to compare age- and sex-standardized annual incidence of primary total hip replacement (THR) and types of implants used for primary hip osteoarthritis (OA) in Denmark, Finland, Iceland, Norway and Sweden.

Methods?The data on THR were from the national total hip replacement registries, and population data were from the national statistics agencies. Annual incidence density per 100,000 was calculated for each 5-year age group and it was age-standardized using the WHO European standard population.

Results?Crude country-specific annual incidence (all ages) for 1996–2000 varied between 73 and 90. WHO age-standardized annual incidence (all ages) varied between 61 (Finland) and 84 (Iceland). For the ages 50–89, comprising 94–98% of all THRs for OA, annual incidence varied between 217 (Finland) and 309 (Iceland). For Norway, the sex incidence ratio (women/men) was 2, and for the other countries it was between 1.1 and 1.3. The use of uncemented and hybrid replacements was considerably higher in Finland and Denmark than in the other countries.

Interpretation?We found overall similarity in THR incidence between the 5 Nordic countries, but substantial differences between women and men, and in the use of different types of implant. Population-based, age-standardized and disease-specific information on THR incidence is required in order to properly explore the causes of differences in provision and practice of THR in different countries, regions and groups, and it will aid in projecting future needs.     

Peptic ulcer disease and heart disease are associated with periprosthetic fractures after total hip replacement

Background and purpose There have been no published studies assessing the possible association of medical comorbidities with periprosthetic fracture risk. We therefore assessed whether medical comorbidity is associated with risk of periprosthetic fractures after total hip replacement (THR).

Material and methods We used prospectively collected data from 1989–2008 in the Mayo Clinic Total Joint Registry for 2 cohorts: primary THR and revision THR. The main variables of interest were Deyo-Charlson comorbidities at the time of surgery. Outcome of interest was p ostoperative periprosthetic fracture at postoperative day 1 onwards. Multivariable

Cox regression models were additionally adjusted for age, sex, body mass index, American Society of Anesthesiology (ASA) class, and operative diagnosis.

Results We identified 14,065 primary THRs and 6,281 revision THRs with mean follow-up times of 6.3 and 5.6 years, respectively. There were 305 postoperative periprosthetic fractures in the primary THR cohort and 330 in the revision THR cohort. In patients who underwent primary THR, 2 comorbidities were associated with higher risk of periprosthetic fracture: peptic ulcer disease with adjusted hazard ratio of 1.5 (95% CI: 1.1–2.2) and heart disease with adjusted hazard ratio of 1.7 (CI: 1.2–2.4). In patients with revision THR, peptic ulcer disease was associated with a higher adjusted risk of periprosthetic fracture, 1.6 (CI: 1.1–2.3).

Interpretation Peptic ulcer disease and heart disease in primary THR patients and peptic ulcer disease in revision THR patients were associated with higher postoperative periprosthetic fracture risk. Further studies are needed to understand whether disease severity or specific medications used for treatment, or both, are responsible for this association. This may allow identification of modifiable factors.     

Total hip arthroplasty for rheumatoid arthritis in younger patients: 2,557 replacements in the Finnish Arthroplasty Register followed for 0–24 years

Background?The results of total hip arthroplasty (THA) in young patients with rheumatoid arthritis (RA) have been reported in only a few studies. On a nationwide level, the outcome of THA in these patients is unknown. We evaluated the population-based survival of THA in patients under 55 years of age with RA and factors affecting the survival.

Patients?Between 1980 and 2003, 2,557 primary THAs performed for RA in patients less than 55 years of age were reported to the Finnish Arthroplasty Register.

Results?Proximally circumferentially porous-coated uncemented stems had a 15-year survival rate of 89% (95% CI 83–94) with aseptic loosening as endpoint. The risk of stem revision due to aseptic loosening was higher with cemented stems than with proximally porouscoated uncemented stems implanted during the same period (RR 2.4; p < 0.001). In contrast, Cox regression analysis showed that the risk of cup revision was significantly higher for all uncemented cup concepts than for all-polyethylene cemented cups with any cup revision as endpoint. There were no significant differences in survival between the THR concepts.

Interpretations?Uncemented proximally circumferentially porous-coated stems and cemented all-poly-ethylene cups are currently the implants of choice for young patients with RA.     

Acute total hip replacement for acetabular fractures: A systematic review of the literature

Introduction

Immediate total hip replacement (THR) in patients with acetabular fractures is controversial because of concerns about high complication rates. The current article is a systematic review of the literature on the use of acute THR for the treatment of acetabular fractures.

Materials and methods

This systematic review included studies published in English between 1992 and 2012 of subjects with acetabular fracture undergoing immediate THR. Outcomes of interest included indications; clinical assessment, including walking ability; comparison with control group; associated procedures, and rate of complications, such as loosening or revision surgery.

Results

This review identified six studies, of which only one included a control group. Acute THR was associated with satisfying outcomes with regard to clinical assessment and walking ability. The comparative study assessed the difference between acute THR and delayed THR in acetabular fractures: improved outcomes were observed in the delayed THR group, although the differences between the two groups were not statistically significant.

Discussion

According to data reported in the literature, acute primary THR can be successful in patients with poor bone quality, combined acetabular and femoral neck fractures, or pathological fractures and concurrent osteoarthritis of the hip. Relative indications include old age, delayed presentation, substantial medical comorbidities, and pathologic obesity. Clinical outcomes with acute THR were similar to those with delayed THR. Although the results reported in the six studies reviewed here were satisfying overall, there is limited evidence in this area in the existing literature and future prospective investigations are required.

Conclusion

Data reported in the literature indicate that immediate THR can be successful in appropriately selected elderly patients or patients with extensive osteoporosis, combined acetabular and femoral neck fractures or pathological fractures. There is currently a limited evidence base for THR in patients with acetabular fractures; therefore, physicians’ practice and expertise are the most useful tools in clinical practice.     

Hüftendoprothese bei Koxarthrose nach Azetabulumfrakturen

Aim

This study analyzed factors influencing prosthetic hip function after total hip replacement surgery (THR) including the initial acetabular fracture type, patient age, and the acetabular reconstruction component.

Material and method

A total of 45 patients with secondary arthritis due to acetabular fracture and THR were prospectively selected from our total hip arthroplasty register between July 1999 and December 2005. The initial acetabular fracture was classified according to the AO system and the statistical analysis of the preoperative and postoperative Harris hip score (HHS) was correlated with age, type of fracture and acetabular reconstruction component.

Results

Of the fractures 44 could be classified and 39 patients were included in the study. Median follow-up period was 15 months. HHS increased on average from 35 to 91. Only type C fractures showed statistical relevance and age had no influence on the median increase in HHS (53–55). Most important was the preoperative HHS and the restoration of proper hip anatomy and rotational alignment.

Conclusion

Patient age and injury severity influenced the preoperative function and hence the HHS after THR; however, these factors had no influence on the individual increase in the HHS.     

No increased stem subsidence after arthroplasty in young patients with femoral head osteonecrosis:41 patients followed for 1–9 years

Background?Poor bone stock in patients with osteonecrosis of the femoral head may be a reason for poor outcome after hip replacement. One way of studying bone quality is to measure implant migration. We thus investigated the clinical and radiographic results of cementless THR in younger patients with femoral head osteonecrosis.

Patients and methods?We studied hips in 41 patients (mean age 48 (25–63) years) with a cementless hip arthroplasty after late stage osteonecrosis. Clinical evaluation was by the Harris hip score, the WOMAC score and the SF-36 score. Stem subsidence was measured with the Ein Bild Roentgen Analyse femoral component analysis (EBRA-FCA) at 3, 12, 24, 60, and 72 months after operation. The average duration of follow-up was 7(1–9) years, with less than 2 years for 2 patients.

Results?There was no revision of any hip. No radiographic or clinical stem loosening was seen. After 60 months, the cementless stems showed a median subsidence of –0.7?mm (95% CI: –0.9 to –0.2). No femoral osteolysis occurred. Femoral radiolucent lines, all < 1?mm, were seen in 10 hips. At the latest follow-up the Harris hip score was 83 (23–100) points.

Interpretation?Our findings for porous-coated stems in patients with femoral osteonecrosis indicate no greater risk of stem subsidence and rate of osteolysis after an average of 7 years follow-up. Thus, we continue to use uncemented stems in younger patients with femoral osteonecrosis. However, continued follow-up will be necessary to evaluate the long-term outcome.     

Influence of Hip Geometry Reconstruction on Frontal Plane Hip and Knee Joint Moments During Walking Following Primary Total Hip Replacement

BackgroundFollowing total hip replacement (THR), hip geometry reconstruction parameters such as the femoral offset (FO) correlate with hip stability and wear. The purpose of this study is to determine the relationship between hip geometry parameters and knee and hip joint loading during walking.MethodsForty-one patients were examined before and a minimum of 1 year after primary THR. Pearson correlation coefficient (r) was performed to identify relationships between radiographic parameters and gait data. In addition, we divided patients into 2 groups according to the restoration of the FO (within ±5 mm vs more than 5 mm increment).ResultsThe FO and global offset (GO) showed a positive correlation with the first (r = 0.469, P = .002; r = 0.542, P < .001) and second (r = 0.365, P = .019; r = 0.484, P = .001) knee adduction moment (KAM). The neck-shaft angle revealed a negative correlation with the first hip adduction moment (r = ?0.375, P = .047). The reconstruction of FO with an increment of more than 5 mm was associated with a significant higher first KAM (+16%, P = .045) compared to the restored group.ConclusionOur findings suggest that abnormal hip and knee joint loading during walking after THR have a biomechanical background originating from hip geometry reconstruction. Patients with a high FO/GO were more likely to have an increased KAM during walking or vice versa. Surgeons need to be aware that an accurate control of FO, GO, and neck-shaft angle restoration in THR has an impact on hip and knee joint loading that may influence degenerative changes of the knee and higher wear of the artificial hip joint, respectively.