Hip Center Research Articles

Jumbo cup in hip joint renovation may cause the center of rotation to increase.

BACKGROUNDUtilizing the large jumbo cup in revision total hip arthroplasty is an effective approach to cure many lacunar and segmental peripheral bone defects. However, with the use of the jumbo cup, the center of the hip joint may become elevated relative to the primary acetabulum, and the diameter of the large cup is greater.AIMTo study the height and the significance of the elevation of the hip joint center.METHODSEighty-eight patients matched the criteria for this condition and were included in the study. The center height of the hip joint was measured relative to the opposite normal hip joint. The diameter of the jumbo cup was measured and checked according to operation notes, and the diameter of the jumbo cup was measured with a prosthesis label. Then, the horizontal and vertical centers of rotation were measured on the surgical side and opposite side. The average center height of the hip joint on the renovated side and the opposite side and the position of the hip cup relative to the teardrop were compared using a paired t-test.RESULTSRadiometric analysis showed that the average hip joint center was elevated by 7.6 mm. The rotational center height delta of the renovated hip was 7.6 ± 5.6 mm, and there was an obvious difference between the two groups (P = 0.00). The difference in horizontal distance was 0.5 ± 5.1 mm (-11.5 -14.0 mm), and there was no obvious difference between the two groups (P = 0.38). According to the foreign standard, the rotational center height delta of the renovated hip was 7.5 ± 6.2 mm, and there was a significant difference between the two groups (P = 0.00). There was no obvious difference between the domestic and foreign standards (P > 0.05) between the two groups.CONCLUSIONThe application of the jumbo cup elevates the rotational center of the hip joint, but it is feasible and effective to use the jumbo cup.

Biomechanics Differ for Individuals With Similar Self-Reported Characteristics of Patellofemoral Pain During a High-Demand Multiplanar Movement Task.

Patellofemoral pain (PFP) is often categorized by researchers and clinicians using subjective self-reported PFP characteristics; however, this practice might mask important differences in movement biomechanics between PFP patients. To determine whether biomechanical differences exist during a high-demand multiplanar movement task for PFP patients with similar self-reported PFP characteristics but different quadriceps activation levels. Cross-sectional design. Biomechanics laboratory. A total of 15 quadriceps deficient and 15 quadriceps functional (QF) PFP patients with similar self-reported PFP characteristics. In total, 5 trials of a high-demand multiplanar land, cut, and jump movement task were performed. Biomechanics were compared at each percentile of the ground contact phase of the movement task (α = .05) between the quadriceps deficient and QF groups. Biomechanical variables included (1)whole-body center of mass, trunk, hip, knee, and ankle kinematics; (2)hip, knee, and ankle kinetics; and (3)ground reaction forces. The QF patients exhibited increased ground reaction force, joint torque, and movement, relative to the quadriceps deficient patients. The QF patients exhibited: (1)up to 90, 60, and 35N more vertical, posterior, and medial ground reaction force at various times of the ground contact phase; (2)up to 4° more knee flexion during ground contact and up to 4° more plantarflexion and hip extension during the latter parts of ground contact; and (3)up to 26, 21, and 48 N·m more plantarflexion, knee extension, and hip extension torque, respectively, at various times of ground contact. PFP patients with similar self-reported PFP characteristics exhibit different movement biomechanics, and these differences depend upon quadriceps activation levels. These differences are important because movement biomechanics affect injury risk and athletic performance. In addition, these biomechanical differences indicate that different therapeutic interventions may be needed for PFP patients with similar self-reported PFP characteristics.

Estimating soft tissue artifact of the thigh in high knee flexion tasks using optical motion Capture: Implications for marker cluster placement

Soft tissue artifact in motion capture is widely accepted as a significant source of error in kinematic and kinetic measurements. Non-invasive methods of estimating soft tissue artifact, those requiring only motion capture, provide a feasible method to evaluate marker placement on a segment and enable recommendations for marker configurations which can minimize soft tissue artifact. The purpose of this study was to investigate the effect of thigh marker cluster location on soft tissue artifact during high knee flexion (>120 deg) as unique deformation of soft tissue occurs in this range (e.g. thigh-calf contact). Motion of the pelvis and lower limbs were recorded during squatting and kneeling in fifty participants. Six rigid marker clusters were affixed to the skin on the anterior, lateral, and anterolateral aspect, at the distal and middle third of the thighs. To estimate soft tissue artifact, the functional hip joint center was reconstructed relative to the pelvis cluster and each of the six thigh clusters throughout motion. The difference in the position of these two points was input into Bland-Altman analyses and compared between the thigh clusters. Across the tasks, the total mean difference ranged from 2.81 to 8.95 cm while the lower and upper limits of agreement ranged from –0.79 to 2.54 cm and 5.04 to 17.65 cm, respectively. Using this non-invasive method, the mid-anterolateral cluster was least susceptible to soft tissue artifact and thus would be recommended, while the lateral clusters were most susceptible and should avoided in high knee flexion and similar tasks.

Bone impaction grafting and anti-protrusio cages in high-grade acetabular defects: a 22-year single centre experience.

Report clinical and radiological long-term follow-up (FU) outcome of bone impaction grafting (BIG) and anti-protrusio cage (APC) technique in hip revision surgery. We analysed data on complications, as well as the clinical and radiological outcome of patients treated using this technique at our institution. We evaluated the acetabular bone stock renovation, acetabular component stability and its radiological migration. The clinical parameters considered were the Visual Analogue Scale (VAS) and the modified Harris Hip Score (mHHS). Forty hips, with a mean 14.3-year FU, were included. This technique showed good clinical long-term results in an elderly and low-demanding population (mean age at surgery 71.4 ± 12.1years). The radiological results were not as good as clinical results: 67.5% of cases had a radiographic evidence of resorption of less than 1/3 of the bone graft; 27.5% had a resorption ranging from 1/3 and ½ of the graft, and 5% had more than ½ of the graft. Paprosky type III B reported worse results in terms of graft resorption and a greater migration of the APC (p < 0.001). The survival rate was 95% and a 2.5% rate of septic failure was recorded. Impaction grafting with femoral head and APC is an effective technique for treating high-grade acetabular defects. APC reconstructs the hip centre of rotation, avoiding loading forces on the underlying bone graft that can be correctly integrated. At long-term FU, satisfactory clinical results, not strictly correlated to radiological signs of integration, were observed; Paprosky type III B reported worse results in terms of graft resorption and a greater migration of the APC.

A Workflow Change in Anterior Approach Total Hip Arthroplasty Leads to Improved Accuracy of Biomechanical Reconstruction Without Increased Risk of Complications.

BackgroundDuring anterior approach total hip arthroplasty (THA), the femur may be an impediment for acetabular access, pushing reamers proximally and consequently altering the hip center. In an effort to address this, the senior author changed the surgical workflow from acetabulum first (AF) to femur first (FF). The objective of this study was to compare the precision of biomechanical hip reconstruction and clinical outcomes between the FF and AF techniques.MethodsThis is a retrospective, case-control study of 267 anterior THAs (132 AF and 135 FF). A normal, contralateral hip was used to determine the native biomechanical parameters. Using a calibrated software program, radiographic measurements were performed to calculate the hip center position, femoral offset, global offset, and leg length of the operative and native hips using 2-week postoperative anteroposterior pelvis radiographs. Demographics, operative information, hemoglobin change, and complication data were obtained. Functional outcomes were assessed with the Hip Dysfunction and Osteoarthritis Outcome Score for Joint Replacement survey at 1 year postoperatively.ResultsThe groups exhibited similar demographic characteristics. The FF group demonstrated significantly more accurate and more precise reconstruction of horizontal and vertical hip centers, femoral offset, and leg length. There was no significant difference in operative time, hemoglobin change, complication rate, or Hip Disability and Osteoarthritis Outcome Score, Joint Replacement scores between groups.ConclusionsThe FF technique allowed for more accurate and precise reconstruction of the hip center, leg length, and offset in THA than the AF workflow. Furthermore, the FF approach demonstrated no significant differences in complication rate or blood loss, nor in clinical outcomes.Level of EvidenceTherapeutic Study Level III.

Multicup reconstruction technique for the management of severe protrusio acetabular defects

BackgroundIn revision hip arthroplasty, managing the large protrusio acetabular defects remains a challenge. The report described a novel technique which employs a trabecular metal revision shell as a super-augment to buttress the superior medial structure.MethodsBetween January 2015 and December 2018, the multicup reconstruction was performed in 21 patients with severe protrusio acetabular defects. The revision shell, plus two similar porous acetabular components was implanted into the initial shell to create a “multicup” construct. The functional outcomes were evaluated in terms of the Harris Hip Score. Acetabular loosening, restoration of hip center of rotation, and bone ingrowth etc., were radiographically assessed. The survival rate of the implants was also evaluated.ResultsA followup lasting a mean time of 31 months (range, 18–57 months) revealed that the average Harris Hip Score improved from preoperative 37.0 ± 7.1 to postoperative 76.4 ± 9.0. There were no revisions due to acetabular loosening. The horizontal offset increased by an average of 14 mm, and the vertical offset decreased by an average of 18 mm. Eighteen of the 21 patients (86 %) met at least 3 of 5 criteria associated with bone ingrowth. The survivorship free from re-revision for acetabular loosening after 2 years was 100 %.ConclusionsThe multicup reconstruction technique was a simplified re-revision procedure for managing the severe protrusio acetabular defects and could achieve a high survival rate.Level of evidenceTherapeutic study, Level IVa.

Acetabular Edge Loading During Gait Is Elevated by the Anatomical Deformities of Hip Dysplasia.

Developmental dysplasia of the hip (DDH) is a known risk factor for articular tissue damage and secondary hip osteoarthritis. Acetabular labral tears are prevalent in hips with DDH and may result from excessive loading at the edge of the shallow acetabulum. Location-specific risks for labral tears may also depend on neuromuscular factors such as movement patterns and muscle-induced hip joint reaction forces (JRFs). To evaluate such mechanically-induced risks, we used subject-specific musculoskeletal models to compare acetabular edge loading (AEL) during gait between individuals with DDH (N = 15) and healthy controls (N = 15), and determined the associations between AEL and radiographic measures of DDH acetabular anatomy. The three-dimensional pelvis and femur anatomy of each DDH and control subject were reconstructed from magnetic resonance images and used to personalize hip joint center locations and muscle paths in each model. Model-estimated hip JRFs were projected onto the three-dimensional acetabular rim to predict instantaneous AEL forces and their accumulative impulses throughout a gait cycle. Compared to controls, subjects with DDH demonstrated significantly higher AEL in the antero-superior acetabulum during early stance (3.6 vs. 2.8 × BW, p ≤ 0.01), late stance (4.3 vs. 3.3 × BW, p ≤ 0.05), and throughout the gait cycle (1.8 vs. 1.4 × BW*s, p ≤ 0.02), despite having similar hip movement patterns. Elevated AEL primarily occurred in regions where the shallow acetabular edge was in close proximity to the hip JRF direction, and was strongly correlated with the radiographic severity of acetabular deformities. The results suggest AEL is highly dependent on movement and muscle-induced joint loading, and significantly elevated by the DDH acetabular deformities.

La position du corps en décubitus latéral versus dorsal influence-t-elle le risque de lésion neuro-vasculaire lors d’une arthroplastie totale de la hanche ? Une étude d’imagerie par résonance magnétique

BackgroundNeurovascular injury is a critical complication in total hip arthroplasty (THA). However, neurovascular geographic variations around the hip joint in different body positions have not been examined. This study investigated the differences in hip neurovascular geography in the supine and lateral positions using magnetic resonance imaging (MRI). HypothesisThe neurovascular geography of the hip is influenced by differences in surgical body position. Patients and methodsThis was a single-center prospective study of 15 healthy volunteers enrolled between January 2018 and March 2019. Each subject's bilateral hips were scanned with a 3-T MRI scanner in both the supine and lateral positions. In T1-weighted axial images at the level of the hip center, the anterior and posterior acetabular edges were defined as reference points at which retractors are commonly placed during surgery. We measured the distance between the anterior acetabular edge and the femoral nerve (dFN), femoral artery (dFA), and femoral vein (dFV), as well as that between the posterior acetabular edge and the sciatic nerve (dSN). The primary outcome measures were the distances in both the supine and lateral positions. ResultsdFN, dFA, and dFV in the supine and lateral positions (mm, mean±standard deviation) were 25.8±5.6 and 32.4±6.4 (p<0.0001), 25.7±4.5 and 32.2±5.0 (p<0.0001), and 26.5±4.8 and 32.3±5.1 (p<0.0001), respectively. Most of these elements moved anteromedially in the lateral position compared to the supine position. There was no significant difference in dSN between the supine and lateral positions (23.7±4.9 and 24.5±6.5 (p=0.46). DiscussionTHA in the supine position may be accompanied by a higher risk of femoral neurovascular injury than that in the lateral position. The application of our findings could reduce the risk of femoral neurovascular injury during THA. Level of Evidence: III; Prospective Diagnostic case control study.

Obtaining optimum screw placement for revision acetabular prostheses using the sciatic notch as reference

BackgroundThe use of transacetabular screws aid greatly in attaining acetabular component stability during acetabular revision surgery. There are, however, definite risks involved when using this technique. Inserting screws in the posterior superior safe zone has been advocated as a way to do this safely, but recent studies have shown that this does not hold true in conditions where acetabular anatomy is distorted or where the hip centre of rotation has moved. A method to insert these screws more accurately and safely is proposed. Questions/Purposes(1) Can using the greater sciatic notch as reference point when inserting transacetabular screws for revision acetabular cups ensure accurate and safe placement of screws? (2) How does this proposed new method compare with the posterior superior safe zone method? MethodsWith the use of an observational anatomic study we have developed a new method for the insertion of long transacetabular screws. This method uses the greater sciatic notch as a reference point. Our method was tested on 16 cadaveric hips (reamed to simulate revision conditions) and compared to the safe zone method. ResultsOur method achieved placement of 1–3 screws in the target area in all hips without penetration into the pelvis or sciatic notch. With the use of the safe zone only as reference the pelvis was penetrated 7 times and the sciatic notch twice. ConclusionUsing the greater sciatic notch as a reference guide enables the surgeon to engage a supportive bar of bone for one or more long home run screws whilst minimizing penetration of the pelvis and sciatic notch. In this study our method was superior to using the safe zone in isolation.

Long-term results of combined porous tantalum augments and titanium-coated cups for Paprosky type III bone defects in acetabular revision.

The use of porous tantalum augments and titanium-coated cups in primary total hip arthroplasty (THA) with acetabular defects has shown satisfactory outcomes in our centre. The aim of this study was to report the long-term radiological and clinical outcomes of using this combination for Paprosky type III acetabular bone defects in acetabular revision. Between January 2007 and January 2015, 45 patients with Paprosky type III acetabular defects underwent acetabular revision using a combination of porous tantalum augments and titanium-coated cups. Among these, 41 patients (41 hips) had complete follow-up. Thirty-one patients had a Paprosky type IIIA defect, and ten patients had a Paprosky type IIIB defect. No patients had pelvic discontinuity. There were 20 males and 21 females with an average age of 63.2years (range 35-80) at the time of revision surgery. The mean follow-up was 122.8months (range 69-165). The Harris Hip Score (HHS) improved significantly from 32.1 points (range 17-58) pre-operatively to 85.3 points (63-98) at the last follow-up. The Short Form-12 (SF-12) and Hip Dysfunction and Osteoarthritis Outcome Score (HOOS) improved significantly for each item at the last follow-up. Two patients had a high hip centre post-operatively. One patient had recurrent dislocation but did not require re-revision. No further revision of the acetabular components was required, and all hips remained stable at the last follow-up with bony ingrowth of the acetabular components according to the criteria of Moore et al. CONCLUSION: The combination of tantalum augments and conventional titanium-coated cups achieved satisfactory long-term radiographic and clinical outcomes for Paprosky type III acetabular bone defects without pelvic discontinuity.

3D free-hand ultrasound to register anatomical landmarks at the pelvis and localize the hip joint center in lean and obese individuals

3D free-hand ultrasound (3DFUS) is becoming increasingly popular to assist clinical gait analysis because it is cost- and time-efficient and does not expose participants to radiation. The aim of this study was to evaluate its reliability in localizing the anterior superior iliac spine (ASIS) at the pelvis and the hip joint centers (HJC). Additionally, we evaluated its accuracy to get a rough estimation of the potential to use of 3DFUS to segment bony surface. This could offer potential to register medical images to motion capture data in future. To evaluate reliability, a test–retest study was conducted in 16 lean and 19 obese individuals. The locations of the ASIS were determined by manual marker placement (MMP), an instrumented pointer technique (IPT), and with 3DFUS. The HJC location was also determined with 3DFUS. To quantify reliability, intraclass correlation coefficients (ICCs), the standard error of measurement (SEm), among other statistical parameters, were calculated for the identified locations between the test and retest. To assess accuracy, the surface of a human plastic pelvic phantom was segmented with 3DFUS in a distilled water bath in 27 trials and compared to a 3D laser scan of the pelvis. Regarding reliability, the MMP, but especially the IPT showed high reliability in lean (SEm: 2–3 mm) and reduced reliability in obese individuals (SEm: 6–15 mm). Compared to MMP and IPT, 3DFUS presented lower reliability in the lean group (SEm: 2–4 mm vs. 2–8 mm, respectively) but slightly better values in the obese group (SEm: 7–11 mm vs. 6–16 mm, respectively). Correlations between test–retest reliability and torso body fat mass (% of body mass) indicated a moderate to strong relationship for MMP and IPT but only a weak correlation for the 3DFUS approach. The water-bath experiments indicated an acceptable level of 3.5 (1.7) mm of accuracy for 3DFUS in segmenting bone surface. Despite some difficulties with single trials, our data give further rise to the idea that 3DFUS could serve as a promising tool in future to inform marker placement and hip joint center location, especially in groups with higher amount of body fat.

Risk factors for a radiolucent line around the acetabular component with an interface bioactive bone cement technique after primary cemented total hip arthroplasty

AimsThe main aims were to identify risk factors predictive of a radiolucent line (RLL) around the acetabular component with an interface bioactive bone cement (IBBC) technique in the first year after THA, and evaluate whether these risk factors influence the development of RLLs at five and ten years after THA.MethodsA retrospective review was undertaken of 980 primary cemented THAs in 876 patients using cemented acetabular components with the IBBC technique. The outcome variable was any RLLs that could be observed around the acetabular component at the first year after THA. Univariate analyses with univariate logistic regression and multivariate analyses with exact logistic regression were performed to identify risk factors for any RLLs based on radiological classification of hip osteoarthritis.ResultsRLLs were detected in 27.2% of patients one year postoperatively. In multivariate regression analysis controlling for confounders, atrophic osteoarthritis (odds ratio (OR) 2.17 (95% confidence interval (CI), 1.04 to 4.49); p = 0.038) and 26 mm (OR 3.23 (95% CI 1.85 to 5.66); p < 0.001) or 28 mm head diameter (OR 3.64 (95% CI 2.07 to 6.41); p < 0.001) had a significantly greater risk for any RLLs one year after surgery. Structural bone graft (OR 0.19 (95% CI 0.13 to 0.29) p < 0.001) and location of the hip centre within the true acetabular region (OR 0.15 (95% CI 0.09 to 0.24); p < 0.001) were significantly less prognostic. Improvement of the cement-bone interface including complete disappearance and poorly defined RLLs was identified in 15.1% of patients. Kaplan-Meier survival analysis for the acetabular component at ten years with revision of the acetabular component for aseptic loosening as the end point was 100.0% with a RLL and 99.1% without a RLL (95% CI 97.9 to 100). With revision of the acetabular component for any reason as the end point, the survival rate was 99.2% with a RLL (95% CI 97.6 to 100) and 96.5% without a RLL (95% CI 93.4 to 99.7).ConclusionThis study demonstrates that acetabular bone quality, head diameter, structural bone graft, and hip centre position may influence the presence of the any RLL.Cite this article: Bone Joint Open 2021;2(5):278–292.

Developmental Hip Dysplasia Treated with Cementless Total Hip Arthroplasty Using a Straight Stem and a Threaded Cup-A Concise Follow-Up, At a Mean of Twenty-Three Years.

We previously reported the 9-year follow-up results of 121 cementless total hip arthroplasties (THAs) from 1990 to 1994 in 93 patients with developmental dysplasia of the hip (DDH). The present study reports the updated long-term results after a mean follow-up of 23 years. Fifty-seven patients (72 hips) were alive and available for follow-up. Since our previous report, nine THAs had been revised. The cumulative implant survivorship of any component was 87% (95% CI, 78–92%). The cumulative probability of not having aseptic cup loosening was 87% (95% CI, 77–93%) and there was no revision surgery for aseptic stem loosening. In three hips (5%), an exchange of the ball and liner due to polyethylene wear was performed after a mean of 12 years. This study demonstrates that cementless THA for DDH with restoration of the hip joint center provides excellent long-term durability.

Custom Made Monoflange Acetabular Components for the Treatment of Paprosky Type III Defects.

Purpose: Patient-specific, flanged acetabular components are used for the treatment of Paprosky type III defects during revision total hip arthroplasty (THA). This monocentric retrospective cohort study analyzes the outcome of patients treated with custom made monoflanged acetabular components (CMACs) with intra- and extramedullary iliac fixation. Methods: 14 patients were included who underwent revision THA with CMACs for the treatment of Paprosky type III defects. Mechanism of THA failure was infection in 4 and aseptic loosening in 10 patients. Seven patients underwent no previous revision, the other seven patients underwent three or more previous revisions. Results: At a mean follow-up of 35.4 months (14–94), the revision rate of the implant was 28.3%. Additionally, one perioperative dislocation and one superficial wound infection occurred. At one year postoperatively, we found a significant improvement of the Western Ontario and McMaster Universities Arthritis Index (WOMAC) score (p = 0.015). Postoperative radiographic analysis revealed good hip joint reconstruction with a mean leg length discrepancy of 3 mm (−8–20), a mean lateralization of the horizontal hip center of rotation of 8 mm (−8–35), and a mean proximalization of the vertical hip center of rotation of 6 mm (13–26). Radiolucency lines were present in 30%. Conclusion: CMACs can be considered an option for the treatment of acetabular bone loss in revision THA. Iliac intra- and extramedullary fixation allows soft tissue-adjusted hip joint reconstruction and improves hip function. However, failure rates are high, with periprosthetic infection being the main threat to successful outcome.

Evaluation of Serum 25-Hydroxyvitamin D3 and Bone Mineral Density in 268 Patients with Hip Fractures.

ObjectiveThe aim of the present study was to evaluate the relationship among vitamin D nutritional status, bone mineral density, and other factors in elderly patients with brittle hip fractures.MethodsThe present study was a retrospective analysis of 268 patients, 102 men (38.06%) and 166 women (61.94%), with brittle hip fractures admitted to the Hip Joint Center of Tianjin Hospital from February 2016 to June 2018. The median age of the patients was 74 years (range, 50–93 years). The patients were divided into three groups based on age: ≤69 years, 70–79 years, and ≥80 years. Serum 25‐hydroxyvitamin D3 (25(OH) D3), parathyroid hormone (PTH), body mass index (BMI), and bone mineral density (BMD) of the lumbar spine, femoral neck, and hip were measured and statistically analyzed.ResultsThe median serum 25(OH)D3 level of patients was 9.90 (range, 2.60–42.70) ng/mL; the proportion of deficiency was 89.18% and the deficiency was severe in 136 cases (49.25%). The proportion of vitamin D deficiency was significantly lower in men than in women (P = 0.013). With the increase of age, 25(OH)D3 levels gradually decreased (P = 0.044) and PTH levels gradually increased (P < 0.001). There was significantly negative correlation (P < 0.001) between the levels of serum 25(OH)D3 and PTH. There were 200 cases (74.63%) in which T‐values of BMD were less than −2.5 in any part of the lumbar vertebrae, femoral neck, and hip. T‐values in 74 cases (27.61%) were less than −2.5 in all three parts. The T‐values of BMD in men were significantly higher than those in men (P < 0.001). With the increase of age, the femoral neck BMD in men gradually decreased (P = 0.016), and the femoral neck and hip BMD in female gradually decreased (P‐value was 0.001 and 0.003, respectively). Multivariate analysis suggested that gender and BMI were independent risk factors for BMD, and vitamin D deficiency affected BMD.ConclusionVitamin D deficiency is common in patients with brittle hip fractures, especially in women. With the increase of age, vitamin D continues to decrease and PTH increases. The decrease of BMD in patients with hip fractures is the result of a combination of age, gender, BMI, and vitamin D content.

Functional and radiographical results of asymmetrically reconstructed total hip arthroplasty in patients with bilateral dysplastic arthritic hips with one hip Crowe II\u2013III and the other Crowe IV: a retrospective cohort study

BackgroundThe study aimed to evaluate the functional and radiographical results of asymmetrically reconstructed total hip arthroplasty in patients with bilateral dysplastic arthritic hips with one hip Crowe II–III and the other hip Crowe IV.Materials and methodsFrom April 2006 to April 2019, we evaluated 23 patients who had a reconstruction of one Crowe II–III hip with high hip center (HHC) and the other Crowe IV hip at the anatomical position (H group). The radiographic and clinical outcomes were compared with those of a control group of 19 patients with bilateral dysplasia who had one Crowe IV hip and the contralateral hip both reconstructed in the anatomical position (A group). Medical records and radiographs were reviewed, and a complete follow-up was conducted for all patients.ResultsThe mean vertical center of rotation (V-COR) and horizontal center of rotation (H-COR) in the H group were 30.6 ± 5.8 mm and 30.0 ± 5.5 mm, respectively. In the A group, the corresponding values were 14.0 ± 4.3 mm and 23.0 ± 2.3 mm, respectively. A significant difference was found in terms of V-COR and H-COR between the two groups, and no significant difference was shown regarding the cup inclination, abductor lever arm (ALA), ALA ratio, and leg length discrepancy (LLD). Three patients of the H group and four patients of the A group exhibited LLD > 10 mm. All seven patients who had LLD > 10 mm underwent the shortening subtrochanteric osteotomy (SSTO) of the Crowe IV hip. Subgroup analysis based on the presence and absence of SSTO showed that the LLD of the SSTO group was greater than that of the non-SSTO group in both groups, but the difference was only statistically significant in the A group. At the last follow-up, the mean Harris Hip Scores significantly improved in the two groups, and there was no revision during the follow-up period. In the H group, four patients presented with a slight limp and three patients with a moderate limp, while it was six patients and one patient in the A group, respectively.ConclusionsAsymmetrical reconstruction in patients with bilateral dysplastic arthritic hips with one hip Crowe II–III and the other Crowe IV is acceptable and comparable when compared with bilateral anatomical reconstruction.Level of evidenceIII, retrospective observational study.Trial registration Chinese Clinical Trail Registry. ChiCTR2000033848

Total hip arthroplasty after periacetabular osteotomy versus primary total hip arthroplasty: a propensity-matched cohort study.

Controversy still exist regarding the outcomes of total hip arthroplasty (THA) after periacetabular osteotomy (PAO). The purpose of this study was to compare the clinical and radiologic outcomes of THA after PAO with primary THA based on balanced baseline characteristics with propensity score matching. Using propensity score matching, 1:2 matched cohort to facilitate comparison between patients who underwent primary cementless THA with or without previous PAO. Then, we compared the operative time, blood loss, complications, postoperative clinical score, cup size, position, and alignment of acetabular cup, and degree of bony coverage on cup between the two groups. Thirty-five patients with 37 hips who underwent THA after PAO were successfully matched to 70 patients with 74 hips who underwent primary THA. The operative time and blood loss in THA after PAO were significantly longer and larger than those in primary THA (P < 0.001 and = 0.0067, respectively). Clinical score showed no difference between the groups (P > 0.05). For THA after PAO, the cup size and bony coverage were larger (P = 0.0014 and < 0.001, respectively), and the hip center was significantly higher and laterally (P < 0.001 and < 0.001, respectively) comparing primary THA. This study demonstrated longer operative time and larger blood loss without difference in the postoperative clinical score or complications between THA after PAO and primary THA. Furthermore, THA after PAO provided larger cup size and superolaterally positioned cup center without difference in the cup inclination or anteversion comparing primary THA.

Toe-out gait decreases knee load during stair descent in healthy individuals

IntroductionBoth toe-out (TO) and toe-in (TI) gaits decrease knee load during walking and stair ascent. However, few reports have focused on stair descent, which requires a higher load compared with walking. ObjectivesThe purpose of this study was to investigate the effect of foot progression angle (FPA) on knee joint load and related variables during stair descent. MethodsTwenty-two healthy young adults performed a stair descent task at a predefined speed of 90 steps/min with normal gait, TO gait (15° > normal), and TI gait (15° < normal). 3D motion analysis was conducted. In addition, the ground reaction force (GRF) with 3 components, center of pressure (COP) positions, and sagittal and frontal plane hip and knee joint kinematic and kinetic variables were recorded during stair descent. ResultsThe medial GRF increased, and the COP position was more lateral in TO gait compared with normal and TI gait during stair descent. TO gait exhibited a significant decrease in the peak knee adduction moment by ∼20% compared with normal gait and by ∼23% compared with TI gait. In addition, the knee flexion moment in TI gait significantly increased compared with normal and TO gait. ConclusionsTO gait decreases knee joint load during stair descent. Our results might have important implications for patients with knee osteoarthritis (OA) or those at risk of developing knee OA. Moreover, it will be of great interest to those involved in the research or clinical practice dealing with the role of gait in pathologic conditions, such as OA.

CORR Insights®: Medialization of the Hip's Center with Periacetabular Osteotomy: Validation of Assessment with Plain Radiographs.

CORR Insights®: Medialization of the Hip's Center with Periacetabular Osteotomy: Validation of Assessment with Plain Radiographs.

Does Cup Position at the High Hip Center or Anatomic Hip Center in THA for Developmental Dysplasia of the Hip Result in Better Harris Hip Scores and Revision Incidence? A Systematic Review.

One goal of THA is to restore the anatomic hip center, which can be achieved in hips with developmental dysplasia by placing cups at the level of the native acetabulum. However, this might require adjuvant procedures such as femoral shortening osteotomy. Another option is to place the cup at the high hip center, potentially reducing surgical complexity. Currently, no clear consensus exists regarding which of these cup positions might offer better functional outcomes or long-term survival. We performed a systematic review to determine whether (1) functional outcomes as measured by the Harris hip score, (2) revision incidence, and (3) complications that do not result in revision differ based on the position of the acetabular cup (high hip center versus anatomic hip center) in patients undergoing THA for developmental dysplasia of the hip (DDH). We performed a systematic review using Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, including studies comparing the functional outcomes, revision incidence, and complications of primary THA in dysplastic hips with acetabular cups placed at the high hip center versus those placed at the anatomic hip center, over any time frame. The review protocol was registered with PROSPERO (registration number CRD42020168183) before commencement. Of 238 records, eight comparative, retrospective nonrandomized studies of interventions were eligible for our systematic review, reporting on 207 hips with cups placed at the high hip center and 268 hips with cups at the anatomic hip center. Risk of bias within eligible studies was assessed using the Risk Of Bias In Non-randomized Studies of Interventions tool. Due to low comparability between studies, data could not be pooled, so these studies were assessed without summary effects. Six studies compared Harris hip scores, two of which favored high hip center cup placement and three of which favored anatomic hip center cup placement, although none of the differences between cohorts met the minimum clinically important difference. Five studies reliably compared revision incidence, which ranged from 2% to 9% for high hip center at 7 to 15 years and 0% to 5.9% for anatomic hip center at 6 to 16 years. Five studies reported intra- and postoperative complications, with the high hip center being associated with higher incidence of dislocation and lower incidence of neurological complications. No clear difference was observed in intraoperative complications between the high hip center and anatomic hip center. No obvious differences could be observed in Harris hip score or revision incidence after THA for osteoarthritis secondary to DDH between cups placed at the anatomic hip center and those placed at the high hip center. Placement of the acetabular cup in the high hip center may lead to higher risk of dislocation but lower risk of neurologic complications, although no difference in intraoperative complications was observed. Surgeons should be able to achieve satisfactory functional scores and revision incidence using either technique, although they should be aware of how their choice influences hip biomechanics and the need for adjunct procedures and associated risks and operative time. These recommendations should be considered with respect to the several limitations in the studies reviewed, including the presence of serious confounding factors and selection biases, inconsistent definitions of the high hip center, variations in dysplasia severity, small sample sizes, and follow-up periods. These weaknesses should be addressed in well-designed future studies. Level III, therapeutic study.