Conventional Total Hip Replacement Research Articles

A Meta-Analysis to Evaluate Implant Survival and Benefits of the Use of Dual Mobility Constructs in Total Hip Replacement Following Hip Fracture.

Total hip replacement (THR) is commonly performed to treat hip fractures. Dual-mobility constructs (DMCs) are increasingly used for this indication. The aimof this study was to use evidence synthesis techniques to estimate net all-cause construct survival for THR with DMC performed for hip fracture. Additionally, we aimed to investigate and describe differences in all-cause construct survival (if present) between THRs performed with DMC (DMC-THR) or with a conventional bearing construct following hip fracture. We performed a systematic review and meta-analysis of published studies (including joint registries), including DMC-THR for hip fracture which provided Kaplan-Meier (KM) survival estimates. The primary outcome was all-cause construct survival over time. The study was prospectively registered on PROSPERO (CRD42020173117). A total of 557 papers and 17 registry reports were identified. Six studies (four registry reports, one matched-pair cohort study utilising joint registry data, and one single-institution case series) met the inclusion criteria, including 17,370 DMC THRs and 167,377 conventional THRs. Five-year KM survival estimates (95% confidence intervals) were similar at 95.4% (94.9 to 95.8%) for DMC-THR and 96.2% (96.0 to 96.4%) for conventional THR. The relative risk of revision for DMC-THR at five years was 1.21 (1.05 to 1.41). These results suggest that DMC-THR has a lower all-cause survival than conventional THR following hip fracture. This analysis does not support the routine use of DMC-THR over conventional bearing THR.

Changes in leg length and hip offset in navigated imageless vs. conventional total hip arthroplasty

While previous studies on navigated total hip replacement (nTHA) focused on acetabular component positioning, we compared the results of nTHA with conventional total hip replacement (cTHA) in respect of changes in leg length and hip offset. In a single-center study results radiographic parameters of patients with unilateral THA were included. Data were retrospectively analyzed from computer navigation data and radiographs. Analysis concentrated on the discrepancy in leg length (LLD) and hip offset (OSD) between the affected and unaffected hip. The effect of the procedure was defined as the difference between postoperative and preoperative LLD and OSD values in each group. 2332 patients were analyzed. Both nTHA and cTHA were effective in restoring LLD and OSD by reducing the preoperative value significantly (p < 0.001). Regarding changes in LLD, no statistical difference between nTHA and cTHA could be found. Changes in OSD nTHA was a slightly more effective than cTHA (− 2.06 ± 6.00 mm vs. − 1.50 ± 5.35 mm; p < 0.05). Both navigated and conventional THA were successful in reconstruction of leg length and hip offset, while postoperative offset discrepancy was significantly lower in the navigated group at the cost of longer operation times. If these results are clinically relevant further investigation is needed.

Comparison between standard and dual mobility implants in total hip arthroplasty for femoral neck fractures in elderly

Background: Dislocation is a major concern after total hip replacement (THR) in displaced fracture neck of femur. Recent studies have shown reduced dislocation rates with dual mobility THR (DMTHR) for femur neck fractures; however, there is a lack of comparative research to show its superiority over conventional THR. Further, its role in the Asian subcontinent, where the patient requires sitting cross-legged or squatting, has not been studied. Methods: A prospective cohort study of 30 elderly patients with displaced NOF with a minimum follow-up of 2-year. Sixteen patients were operated on with DMTHR and fourteen patients with conventional THR. Both the groups were matched; radiological and functional outcomes in terms of Harris hip score (HHS), visual analog scale (VAS), range of motion, and dislocation rate were compared between the two groups. Results: Mean HHS of the DMTHR group was 79.99 at three months and 92.73 at the end of the 2 year postoperatively, which was significantly better than the conventional THR group 59.5 at three months and 88.14 at 2-year. The range of motion was significantly better in the DMTHR group than the conventional THR group. There was no significant difference in radiological outcomes and postoperative dislocation rate between the two groups. Conclusions: Dual mobility implants give better results than conventional implants for primary THA in elderly patients of displaced FNOF regarding better function and greater range of motion. More long-term multicentric studies are still needed.

QUALITY OF LIFE IN PATIENTS WITH TOTAL HIP REPLACEMENT – A PILOT STUDY

Introduction: Total hip joint replacement is the most frequent surgery intervention for the treatment of degenerative diseases. Rehabilitation after surgery plays an instrumental role for functional recovery and returning to the labor market or daily activities. Although postsurgical pain and function improvement are widely explored, there is no focus on other aspects of life influenced by total hip replacement. The most used instruments for quality of life measuring are specific ones, but a number of disadvantages lead to the need for broad–ranged concept. Aim: to evaluate the quality of life in total hip replacement patients undergoing a personalized rehabilitation program and to define its influence on physical, psychological, social and environmental dimensions of life. Material and methods: A personalized rehabilitation program was applied for 7 days in 19 patients who underwent conventional total hip replacement surgery. Quality of life was measured on the first and the last day of their hospital stay by using the WHOQOL-BREF questionnaire. Results: Significantly improved QOL total score was reported for all participants after the rehabilitation course. Comparing QOL in domains shows statistically significant improvement in all of them except "Social relationships." Conclusion: Early rehabilitationwith an individual approach could achieve QOL improvement in different life aspects of THR patients. WHOQOL-BREF could be a useful tool for quality of life assessment after rehabilitation surgical interventions such as total hip replacement.

Hip resurfacing for small-sized osteonecrosis: 73 cases at a median 8 years’ follow-up

IntroductionTotal hip resurfacing arthroplasty (THRA) is an alternative to conventional total hip replacement (THR) in young patients with osteonecrosis of the femoral head. Series have been small, without criteria regarding extent of necrosis, thus vitiating results. We therefore conducted a retrospective assessment of THRA for small necrosis, to determine (1) implant survival, (2) functional scores, and (3) systemic chromium, cobalt and titanium ion concentrations. HypothesisThe study hypothesis was that the revision rate is low, meeting the National Institute for Health and Care Excellence (NICE) criterion of<0.5% revision per year. Material and methodA single-center single-surgeon retrospective study included 62 patients, for 73 RTHAs, with a mean age of 45.6years (range: 23–68years) presenting Ficat stage 3 or 4 osteonecrosis of the femoral head with<330° total Kerboul angle (frontal+lateral angles) on simple preoperative X-ray. Study data comprised implant survival and preoperative and last follow-up functional scores (Postel–Merle–d’Aubigné, Oxford-12, Harris, and Devane) and titanium, chromium and cobalt blood concentrations. Necrosis size was assessed on preoperative Kerboul angle. ResultsAt a median 8years’ follow-up (IQR: 5.9–9.3years), implant survival was 98.6% (95% CI: 97.22–99.98%). Only 1 implant was exchanged, for femoral loosening. Three other patients underwent revision surgery: 2 cases of lavage for infection, and 1 muscle hernia repair. Postel–Merle–d’Aubigné, Oxford-12 and Harris functional scores and Devane activity scores were significantly improved at follow-up, by a median +5 (IQR: 5 to 7), −26 (IQR: −29 to −23), +55 (IQR: 49 to 61) and +1 (IQR: 1 to 2), respectively (all p<0.001). Ion concentrations at last follow-up for titanium, chromium and cobalt were respectively 4.0μg/L (range: 3.6–4.1), 1.1μg/L (range: 0.8–1.9) and 1.1μg/L (range: 0.6–1.8). ConclusionTHRA is a useful option in the long-term for young patients with osteonecrosis with Kerboul angle<330°. Level of evidenceIV, retrospective study.

Evaluation of minimally invasive versus conventional total hip replacement

Background: Total hip replacement (THR) is considered a low-risk and efficient procedure, to improve pain and disability not exposing patients to significant risk burden. Minimally invasive (MIS) approaches of THR are not only desired to add more benefits but also shouldn`t compromise the already accomplished long-term results. Objectives: The purpose of our study was to evaluate the surgical outcome of minimally invasive versus conventional approach total hip arthroplasty. Patients and methods: This study was performed through a prospective; study comparing two patient groups containing 30 patients who had1ry hip replacement (THA) during the period from March 2018 to May 2020 at Qena University Hospital, fifteen of them undergone 1ry THA utilizing conventional approach and the other fifteen patients undergone 1ry THA utilizing mini-invasive approaches. Results: In Conventional THA group (group-A) nine males and six females were included with a mean age (± SD) of 57.2 ± 4.3 years; ranging (50-65 years). Preoperative HHS in-group-A patients ranged 20.3 – 37.1 (mean 26.8 ± 4.7). In Minimally invasive THA group (group-B) eight males and seven females were included with a mean age (± SD) of 57.7 ± 5.1 years; ranging (49-66 years).Preoperative HHS in group-B patients ranged 20.5 – 48.8 (mean 31.1 ± 8.0).The post-operative HHS were 89.56 ±6.11 and 91.94 ±1.91 in the group-A and group-B respectively, no statistically significant variation regarding the mean values was discovered between the two groups. The mean time to resume work in the group-A was 6.87 ±2.23 weeks compared to 5.67 ±1.39 weeks in the group-B with a significant statistical increase regarding group-A. Conclusion: MIS approaches are advantageous in the terms of hospitalization and time to return to work.

Superior functional outcome with dual mobility THR as compared to conventional THR in fracture neck femur: a prospective cohort study.

Introduction: Total Hip Replacement (THR) in displaced Fracture Neck of Femur (FNOF) is associated with higher dislocation rates. Conventional THR with a large femoral head and anterior approach has reduced the instability, but it remains higher than THR done for other aetiology. Recent studies have shown reduced dislocation rates with dual mobility THR (DMTHR) for FNOF; however, there is a lack of comparative research to show its superiority over conventional THR. Further, its role in the Asian subcontinent, where the patient requires sitting cross-legged or squatting, has not been studied. Methods: A prospective cohort study of 103 elderly patients with displaced FNOF with a minimum follow-up of 1-year. Fifty-two patients were operated on with DMTHR and fifty-one patients with conventional THR. Both the groups were matched in terms of demographic data, surgical approach, and postoperative protocol. Radiological and functional outcomes in terms of Harris Hip Score (HHS), Range of motion, Patient Reported Outcome Measures (PROM), and Dislocation rate were compared between the two groups. Results: Mean HHS of the DMTHR group was 76.37 at three months and 87.02 at the end of the 1-year postoperatively, which was significantly better than the conventional THR group 65.65 at three months and 72.96 at 1-year. The range of motion was significantly better in the DMTHR group than the conventional THR group. There was no significant difference in radiological outcomes and postoperative dislocation rate between the two groups. Conclusion: Dual mobility implants give better results than conventional implants for primary THA in elderly patients of displaced FNOF regarding better function and greater range of motion.

Dual mobility THR: Resolving instability and providing near normal range of movement

BackgroundDislocation is a common complication of Total Hip Replacement (THR), particularly when performed in primary (indications with increased risk of instability) and in revision scenarios. Dual mobility THR (DMTHR) minimizes the risk of instability in such scenarios, however most of the evidence is from western literature. Results of DMTHR in Indian scenarios where patient want to go back to their normal routine activities of squatting and sitting cross-legged is lacking. The aim of our study was to evaluate the short to mid-term results of DMTHR for varied indications (both primary and revision) in Indian scenario. To evaluate the outcome of the DMTHR in terms of functional range of motion and the ability to go back to their pre-injury level of activity. MethodsThis is a retrospective study of 150 patients operated with DMTHR between January 2015 to February 2019 with a minimum follow-up of 12 months. Patients were evaluated clinically using Modified Harris Hip Score (HHS), Range of Motion (ROM), and Patient Reported Outcome Measures (PROM) like ability to squat and sit cross legged. Radiological evaluation was done using radiographs to assess loosening, stress shielding, osteolysis. ResultsMean follow up in our study was 25.2 months (Range 12–46 months). Mean Modified HHS was 71.8 ± 8.11 at 6 weeks post-op and 85.8 ± 7.62 at last follow-up. HHS showed excellent outcome in 36 hips (26.7%), good outcome in 76 hips (56.7%), fair outcome in 20 hips (14.6%), poor outcome in 3 hips (2%). All our patients were allowed to squat and sit cross-legged at a mean follow-up period of 13 weeks (8 weeks–20 weeks) except 10 cases of Revision THR where patients were advised not to squat or sit cross-legged. All patients were able to resume their activities of daily living. ConclusionDMTHR in patients of all ages has shown a good short to midterm clinical outcome which is comparable to conventional THR. It confers the benefit of stability allowing our patients to squat and sit cross legged which is often one of the expectation and requirement of a patient undergoing THR in India. DMTHR in both primary and revision scenarios exhibit a low risk of dislocation, complications and revision surgery.

Is dual mobility cup total hip replacement associated with increased incidence of heterotopic ossification compared to conventional total hip replacements in fracture neck of femur patients?

IntroductionThe incidence of heterotopic ossification after total hip replacement is variable in the literature. If symptomatic, it may cause pain and reduced range of motion. Dual mobility total hip replacements have been considered a valuable option for the treatment of femoral neck fractures in the active patients, achieving good range of motion with reduced risk of dislocation. The occurrence of HO may have detrimental effect on this type of articulation and may accelerate polyethylene wear and predispose to intra-prosthetic dislocation. We compared the incidence of HO in DMC versus conventional THR in femoral neck fracture patients across 3 large trauma institutes Patients and methodsThis is a retrospective cohort study which included 334 patients, 223 received DMC replacements, 111 received conventional total hip replacement (THR). Mean age for the DMC group was 72.3 ± 9.9 years and was 72.1 ± 6.8 years for the THR group. Patients were stratified according to specific inclusion and exclusion criteria, and the 1-year follow up X rays were evaluated for the presence of heterotopic ossification by 3 assessors. ResultsThe incidence of HO in the DMC group was 27.1% compared to 12.2% in the THR group (χ2 p value = 0.0001, Relative Risk = 2.22, 95% CI 1.22–4.03, p value = 0.0091). There was no significant effect of gender or age on the incidence of HO in both groups ConclusionsPatients receiving DMC hip replacements are more likely to develop HO as compared to patients receiving conventional THR for femoral neck fractures. Further prospective studies are required to confirm our findings and to assess the indication of HO prophylaxis in patients receiving DMC hip replacements, and the long-term outcomes in these patients

Hip resurfacing generates a more physiological gait than total hip replacement: A case-control study

BackgroundRestoration of the constitutional joint anatomy after hip replacement favours physiological peri-articular soft-tissue tension and kinematics, and is likely to be functionally beneficial. Hip resurfacing (HR) and conventional total hip replacement (THR) are two different options for replacing degenerated hips, and are likely to result in different anatomical reconstruction. We initiated this study to investigate the differences in gait performance between these two prosthetic options, and aimed to answer the following questions: (1) does HR result in better restoration of the frontal hip anatomical parameters, (2) and generate a more physiological gait compared to THR? (3) Does the quality of the anatomical restoration after THR influence gait performance? HypothesesOur hypothesis was that a better anatomical restoration using HR versus THR would produce more physiological (symmetric) gait. MethodsWe retrospectively reviewed 52 patients who had unilateral primary osteoarthritis successfully treated by replacement (40 THRs and 12 HRs). Hip anatomical parameters were measured on standing pelvic radiographs on both the prosthetic and the contralateral healthy hips. Patients undertook gait assessment under both normal and stress conditions at a mean follow-up of 14 months (7 to 16 months). Gait performances were compared between HR and THR, and the relationship between gait performances and quality of frontal anatomical restoration (estimated on radiograph) were assessed. ResultsCompared to the native contralateral side, the HR procedure tended to decrease all independent anatomical radiographic parameters with the exception of the vertical centre of rotation offset, whilst the THR procedure tended to increase them; the difference between HR and THR was only statistically significant for femoral offset and global horizontal offset (increased after THR while reduced after HR). Only 50% of THR and 25% of HR procedures closely anatomically (±15%) recreated both global horizontal offset and global vertical offset. Under normal conditions (normal walking speed and flat ramp), the gait was fairly symmetric for both the HR and the THR patients with a symmetry index of 0.62% and 3.14% respectively. At high walking speed (stress conditions), the symmetry index degraded for both groups, but the gait remained more symmetric in the HR group (2.09%), compared to the THR group (5.74%); nevertheless, the difference remained not statistically significant (p=0.159). We were unable to detect any significant relationship between gait performances and radiographically measured hip frontal anatomical parameters. Discussion/conclusionsHR procedure is more consistent than conventional THR in generating a more physiological gait under stress conditions. Radiographic estimation of the quality of the frontal anatomical hip restoration is of poor value to predict gait performances of THR patients. Level of evidenceIII – retrospective case-control study with prospective data collection.

Results of the Total Hip Arthroplasty Using 3D Printing Technology

Objectives: To study the value of 3D printing of custom THA femoral prostheses with conventional femoral prostheses in total hip arthroplasty for severe hip deformity. Methods: Total hip arthroplasty was used in the treatment of 107 severe hip joint deformity cases from June 2018 to June 2019. Fifty-six patients received conventional hip replacement stems and 51 patients received a custom 3D printed hip replacement stem designed to address their proximal deformity and leg length discrepancy. The operation time, intraoperative blood loss, postoperative weight-bearing time, Harris score before and after the operation, complications after surgery and the main angle measurement of compared to their contralateral hip were evaluated to determine the short-term efficacy of 3D printed total hip replacement femoral prosthesis compared to the common total hip replacement femoral prosthesis. Results: A total of 107 patients were followed up for an average of 12 months. The use of 3D printing technology in the preoperative design and custom prosthesis fabrication was associated with shortened operation time, less intraoperative blood loss, quicker time to postoperative full weight-bearing, and improved the Harris score in 1 year after the operation compared to conventional total hip replacement stem (p&lt;.05). Our results revealed that there was a significant reduction in the femoral anteversion with a value of 13.06 ± 1.93 degrees (mean ± SD) in the custom prosthesis group compared to the conventional hip replacement group. However, there was no significant difference in neck-shaft angle, acetabular angle, and Sharp angle between both groups (p&gt;.05). Conclusion: 3D printing technology created a virtual and realistic simulation, and personalized operation plan for patients with severe hip deformity, which was helpful for surgical treatment. The anatomical characteristics of patients with complex deformities were better addressed using the 3D printed femoral component and resulting in better patient outcomes and provided a new option for surgeons to manage these difficult cases.

Comparison of functional outcome of cemented total hip replacement versus cemented dual-mobility cup total hip replacement for the management of displaced femoral neck fractures in the active elderly patients.

Current guidelines recommend treating displaced femoral neck fractures with a total hip replacement in fit and active elderly patients. Dislocation remains the main complication. Dual-mobility cup (DMC) hip replacements maybe a solution to decrease dislocation, with the benefit of increasing stability, achieving better range of motion and functional outcomes. This is a prospective randomised controlled trial which included 62 patients with Garden III and IV femoral neck fractures. The mean age was 67.2 years. 30 males and 32 females were included, randomised and allocated to 2 treatment groups; a cemented DMC replacement group, or a cemented 32-mm head total hip replacement (THR). The posterior approach was used in all patients. Postoperative functional outcome was assessed using Harris Hip Score (HHS). Health-related quality of life (HRQoL) was assessed using the SF-36 questionnaire. The mean HHS for the DMC group at 4, 6 and 12 months were higher than mean HHS scores for the THR group (p < 0.001). The range of motion at 1 year was statistically better in the DMC group compared to the THR group (p < 0.001). The DMC showed a statistically better effect on the HRQoL measurements as compared to the THR group. There were no dislocations in both groups. DMC hip replacements provide better functional, patient reported outcomes, and range of motion than the conventional THR. Combined with its stability, DMC replacements are a useful solution in managing femoral neck fractures in active elderly patients.Trial serial number 020841 (IRB Number 00007555).

A comparison of patient-reported outcome measures (PROMs) between short and conventional stem hip replacements: a systematic review and meta-analysis.

Short stem hip replacements may allow preservation of proximal bone stock and minimise soft tissue disruption, easing future revision surgery. However patient satisfaction with these implants must be determined before widespread use. We aimed to compare patient reported outcome measures (PROMs) between short and conventional stem hip replacements. A systematic review was conducted according to PRISMA guidelines for studies comparing short and conventional stem hip replacements with validated PROMs. Meta-analyses were performed for studies reporting Harris Hip and WOMAC scores. Study bias was assessed with the Cochrane Risk of Bias tool and Newcastle-Ottawa Scale. 24 studies, incorporating 2593 total hip replacements were included for qualitative analysis. 17 studies were included in the meta-analyses. Of the 7 excluded, 1 study reported the Japanese Orthopaedic Association score and 2 others reported the Oxford Hip score. All three showed no difference between the stems. A meta-analysis of 17 studies reporting Harris hip scores showed no statistically significant difference between short and conventional stems (standard mean difference (SMD) -0.06, 95% CI -0.20-0.07, p = 0.35). 6 studies reported WOMAC scores with higher scores indicating worse outcome. No difference was seen between the two groups (SMD 0.21, 95%CI, -0.01-0.42, p = 0.06). 4 studies reported higher WOMAC scores as better. Once again, a meta-analysis showed no statistically significant difference between the stems (SMD 0.28, 95% CI -0.07-0.63, p = 0.12). Our systematic review showed no difference in PROMs between short and conventional stem total hip replacements. This is in keeping with previous evidence but is a more comprehensive analysis. Short stems may have an important role in younger individuals as they allow preservation of proximal femoral bone, minimal access surgery and are amenable to abnormal anatomy. The current literature is hindered by non-uniform methodologies and outcome assessments across studies. Further, standardised, high quality evidence is required before widespread changes in practice.

How long does a hip replacement last? A systematic review and meta-analysis of case series and national registry reports with more than 15 years of follow-up

SummaryBackgroundTotal hip replacement is a common and highly effective operation. All hip replacements would eventually fail if in situ long enough and it is important that patients understand when this might happen. We aimed to answer the question: how long does a hip replacement last?MethodsWe did a systematic review and meta-analysis with a search of MEDLINE and Embase from the start of records to Sept 12, 2017. We included articles reporting 15-year survival of primary, conventional total hip replacement constructs in patients with osteoarthritis. We extracted survival and implant data and used all-cause construct survival as the primary outcome. We also reviewed reports of national joint replacement registries, and extracted data for a separate analysis. In the meta-analyses, we weighted each series and calculated a pooled survival estimate for each source of data. This study was registered with PROSPERO (CRD42018085642).FindingsWe identified 140 eligible articles reporting 150 series, and included 44 of these series (13 212 total hip placements). National joint replacement registries from Australia and Finland provided data for 92 series (215 676 total hip replacements). The 25-year pooled survival of hip replacements from case series was 77·6% (95% CI 76·0–79·2) and from joint replacement registries was 57·9% (95% CI 57·1–58·7).InterpretationAssuming that estimates from national registries are less likely to be biased, patients and surgeons can expect a hip replacement to last 25 years in around 58% of patients.FundingNational Institute for Health Research, National Joint Registry for England, Wales, Northern Ireland and Isle of Man, and The Royal College of Surgeons of England.

Higher blood loss and transfusion requirement in surface arthroplasty versus conventional total hip replacement.

Background and aim of the work: Surface replacement arthroplasty (SRA) is an alternative to stemmed total hip arthroplasty (THA) providing a femoral bone preserving procedure. Because of the wider surgical dissection, an increased blood loss could be expected. This retrospective study evaluates the transfusion requirement in two homogeneous groups of patients who underwent primary hip replacement electively. Methods: Perioperative haematological data of 42 hip resurfacing procedures and 41 conventional cementless THAs were compared. The pre- and post-operative haemoglobin (Hb) levels and the amount of blood transfusions were registered. The median values were compared with use of the non-parametric Wilcoxon signed-rank test. Results: In the SRA group, a significantly increased (p<0.02) preoperative Hb concentration (13.1 g/dL, range 10.9 to 15.6) was detected in comparison with the THA group (12.5 g/dL, range 10.4 to 15.2). In the resurfacing procedures a median of 900 mL (range 600 to 1500) were transfused vs. 600 (range 300 to 1500) in the conventional THAs, demonstrating a significantly higher transfusion requirement (p<0.04). Conclusions: Whereas hip resurfacing is a femoral bone preserving alternative to conventional THA with comparable clinical and radiographic outcomes, higher blood loss and transfusion requirement may occur. (www.actabiomedica.it)

Dual mobility device reduces the risk of prosthetic hip instability for patients with degenerated spine: A case-control study

IntroductionThe pelvic incidence is an anatomical and biomechanical pelvic parameter determining spine sagittal morphology and kinematics. Stiffening of the lumbo-pelvic complex, a result of degeneration, affects the functional cup positioning, putting prosthetic hip patients at risk of instability. The anti-dislocation dual mobility (DM) device may be clinically advantageous by reducing the risk of prosthetic instability for older patients with spine ageing. Our study aims to answer the following questions: (1) is there a relationship between prosthetic hip instability and the standing cup position, (2) is there a relationships between prosthetic hip instability and the pelvic incidence, (3) is there a relationships between prosthetic hip instability and the severity of the spine degeneration?, (4) is the DM cup device an effective option for reducing the risk of prosthetic instability related to spine degeneration? HypothesisThere is a relationship between prosthetic hip instability and the standing cup position and pelvic parameters. MethodsCase-control study on prospectively collected data since 2009. From 1672 conventional total hip replacements (THR–5.4% dislocation rate) and 1056 DM-THRs (1.1% dislocation rate) performed at our institute since 2009, we created three groups: 33 patients with unstable THR (group 1–case), 41 patients with stable THR (group 2–control), and 42 patients with stable DM-THR (group 3–control). The cup orientation was measured on standing pelvic radiographs and the spino-pelvic parameters were measured on standing EOS™ biplanar images or lateral full spine radiographs. ResultsBy comparing patients from group 1 with those of group 2 we found they had similar cup position (57% versus 51% fitting the safe zone, p=0.58), higher pelvic incidence (58° versus 51°, p=0.01), and more severe spine degeneration (smaller anterior pelvic plane Tilt (2° versus 7° [p=0.002]), a larger pelvic incidence–lumbar lordosis mismatch (17° versus 8° [p=0.005]), and a higher proportion of spino-sacral angle<127° (70% versus 43%, (p=0.02)). Patients from group 3 had similar cup position, pelvic incidence, and spine degeneration compared to patients from group 1. Discussion/ConclusionPatients with spine-hip relation type 2C/D (high pelvic incidence and severe spine degeneration) have an increased risk of instability that is partly compensated for by the use of a DM device. Preoperative screening of patients with abnormal spine-hip relation would improve THR planning and reduce the risk of prosthetic hip instability. The use of a DM device on spine-degenerated elderly patients is probably sound. Level of evidenceIII, case-control study.

Diagnostic Algorithm for Failure Analysis of Painful Total Hip Arthroplasties

Background: Total hip arthroplasty (THA) is one of the most common and successful surgical procedures in orthopedic surgery and clinical success can be characterized by the revision rate and improvement of function, as well as the patient's satisfaction and pain. Despite the clinical success of primary THA with 10-year survival rates as high as 96 % (Swedish Hip Arthroplasty Register, 2011), the prevalence of groin pain after conventional total hip replacement ranges from 0.4 to 18.3 % and activity-limiting thigh pain is still an existing problem linked to the femoral component of uncemented hip replacement in up to 1.9 to 40.9 % of cases in some series. Obvious causes of failure might be identified with clinical examinations and standard radiographs only, whereas the unexplained painful THA still remains a challenge for the surgeon. They can be classified into extra- and intraarticular disorders, the latter being divided into biological and mechanical origins. The onset of the pain after the operation and the differentiation between pain in motion and at rest are helpful to distinguish between mechanical and non-mechanical problems. An infection should be the first diagnosis to be ruled out in a painful THA. It is generally accepted that a clear understanding of the failure mechanism in each case is required prior considering revision surgery. Method: In this review a practical diagnostic algorithm is described for failure analysis in more detail. The evaluation of a painful THA includes a detailed history with an extended analysis of the type of pain, thorough clinical examination including the spine and knee joints, radiographic and laboratory analysis, as well as invasive examinations like joint aspiration and biopsies. Conclusion: This diagnostic algorithm offers an important tool for a sufficient failure analysis in almost all patients with painful THA.

Does Computer-Assisted Femur First THR Improve Musculoskeletal Loading Conditions?

We have developed a novel, computer-assisted operation method for minimal-invasive total hip replacement (THR) following the concept of “femur first/combined anteversion,” which incorporates various aspects of performing a functional optimization of the prosthetic stem and cup position (CAS FF). The purpose of this study is to assess whether the hip joint reaction forces and patient's gait parameters are being improved by CAS FF in relation to conventional THR (CON). We enrolled 60 patients (28 CAS FF/32 CON) and invited them for gait analysis at three time points (preoperatively, postop six months, and postop 12 months). Data retrieved from gait analysis was processed using patient-specific musculoskeletal models. The target parameters were hip reaction force magnitude (hrf), symmetries, and orientation with respect to the cup. Hrf in the CAS FF group were closer to a young healthy normal. Phase-shift symmetry showed an increase in the CAS FF group. Hrf orientation in the CAS FF group was closer to optimum, though no edge or rim-loading occurred in the CON group as well. The CAS FF group showed an improved hrf orientation in an early stage and a trend to an improved long-term outcome.

The impact of proximal femoral morphology on failure strength with a mid-head resection short-stem hip arthroplasty.

Mid-head resection short-stem hip arthroplasty is a conservative alternative to conventional total hip replacement and addresses proximal fixation challenges in patients not suitable for hip resurfacing. It is unclear whether proximal femoral morphology impacts the ultimate failure load of mid-head resection implanted femurs, thus the aim of this study was to investigate the effect of native neck-shaft angle (NSA) and coronal implant alignment on proximal femoral strength. In total, 36 synthetic femurs with two different proximal femoral morphologies were utilized in this study. Of them, 18 femurs with a varus NSA of 120° and 18 femurs with a valgus NSA of 135° were each implanted with a mid-head resection prosthesis. Femurs within the two different femoral morphology groups were divided into three equal coronal implant alignment groups: 10° valgus, 10° varus or neutral alignment. Prepared femurs were tested for stiffness and to failure in axial compression. There was no significant difference in stiffness nor failure load between femurs implanted with valgus-, varus- or neutrally aligned implants in femurs with a NSA of 120° (p = 0.396, p = 0.111, respectively). Femurs implanted in valgus orientation were significantly stiffer and failed at significantly higher loads than those implanted in varus alignment in femurs with a NSA of 135° (p = 0.001, p = 0.007, respectively). A mid-head resection short-stem hip arthroplasty seems less sensitive to clinically relevant variations of coronal implant alignment and may be more forgiving upon implantation in some femoral morphologies, however, a relative valgus component alignment is recommended.

The painful primary hip replacement - review of the literature.

Total hip replacement is one of the most successful surgical procedures of the 20th century (World Health Organisation). The success rate is dependent on the chosen endpoint. Evaluation of the outcome in joint replacement surgery has shifted from the revision rate toward patient satisfaction and quality of life. Patient satisfaction is reported to be up to 96% 16 years postoperatively, but the prevalence of groin pain after conventional total hip replacement ranges from 0.4% to 18.3% and activity-limiting thigh pain is still an existing problem linked to the femoral component of uncemented hip replacement in up to 1.9% to 40.9% of cases in some series. The aim of our article is to review the aetiology, diagnostic procedures and treatment of the painful primary total hip replacement. We discuss the most relevant intrinsic and extrinsic aetiological factors responsible for chronic pain after total hip arthroplasty focusing on comparative studies and randomised controlled trials including diagnostics and management. Detailed analysis of history, clinical examination, imaging and laboratory tests are required prior to any revision for painful total hip arthroplasty. Revision surgery without knowing the underlying pathology should be avoided.