A Biomechanical Comparison of the Back Squat and Hexagonal Barbell Deadlift.

ABSTRACT: Stahl, CA, Regni, G, Tanguay, J, McElfresh, M, Trihy, E, Diggin, D, and King, DL. A biomechanical comparison of the back squat and hexagonal barbell deadlift. J Strength Cond Res 38(5): 815-824, 2024-Coaches often use different exercises to encourage similar strength adaptations and limit monotony. Anecdotally, the hexagonal barbell deadlift (HBD) exhibits similarities to the back squat (BS). To date, research has not examined the empirical differences between these exercises. This study examined kinematic and kinetic differences between the BS and the HBD across different loads. Sixteen resistance-trained individuals (6 men and 10 women) volunteered to participate. Subjects performed 1-repetition maximum (1RM) testing under BS and HBD conditions. Kinematic and kinetic data were collected during performance of both exercises at submaximal (warm-up sets) and maximal (1RM) loads using a 3D motion capture and force-plate system. Results showed that subjects lifted greater 1RM loads in the HBD relative to the BS (p < 0.05; d = -1.75). Kinematic data indicated that subjects exhibited greater maximum forward lean of the trunk and decreased maximum knee flexion while performing the HBD compared with the BS. The BS resulted in higher maximum extension moments at the hip joint than the HBD. Maximum extension moments at the knee joint showed no difference between the exercises. Data suggest that bar design and position facilitate balanced moment arm length at hip and knee joints during performance of the HBD. By contrast, bar position during performance of the BS increases moment arm length at the hip joint, making it a hip-dominant exercise. The present data have implications for the programming of both exercises. Future research should examine differences in muscle-activation strategies between the 2 exercises.

[Clinical value of high frequency ultrasound in the diagnosis of hip joint involvement in patients with ankylosing spondylitis].

OBJECTIVE: To analyze the correlation between hip joint musculoskeletal ultrasound score and ankylosing spondylitis (AS) disease activity, as well as to investigate the value of high frequency ultrasound in the assessment of hip joint involvement in AS. METHODS: The clinical data of 244 patients with AS who were treated in the rheumatology department of from March 2019 to March 2022 were retrospectively analyzed. Among them, there 174 males and 70 females, aged from 19 to 58 years old with an average of (34.22±9.49) years old;the disease duration of AS patients ranged from 8 months to 26 years, with an average of (13.68±4.04) years.The 244 patients were divided into disease group (83 cases) and control group (161 cases) based in the presence of hip joint involuement. According to the the disease activity, patients in the disease group were further categorezed into active phase (45 cases) and stable phase (38 cases). The ultrasound scores of patients in the active and stable phases of the disease group and the control group were compared. Relevant factors of hip joint involvement in AS patients were analyzed, and analyze the correlation between ultrasound score and Bath ankylosing spondylitis disease activity score index(BASDAI), Bath ankylosing spondylitis functional index(BASFI), visual analogue score of pain (VAS), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and the correlation between hip joint capsule score and tendon attachment end score and BASDAI, BASFI, VAS, CRP and ESR. RESULTS: The hip joint capsule score(3.06±1.12), femoral head score(1.45±0.43), tendon attachment end score(3.28±1.30) and total ultrasound score(6.65±2.31) of the disease group were higher than those of the control group(1.51±0.48)、(0.66±0.27)、(1.61±0.53)、(3.81±1.44)scores (P<0.05). Multifactor Logstic regression analysis showed that the course of disease, hip joint capsule score and total ultrasound score were independent risk factors for hip involvement in AS patients.The hip capsule score (3.65±1.22)and total ultrasound score(8.28±2.33) in the active phase of the disease group were higher than those in the stable phase (2.48±1.04)、( 6.82±1.96)scores(P<0.05). The hip joint capsule score and total ultrasonic score of AS patients were positively correlated with BASDAI, BASFI, VAS, CRP, and ESR (P<0.05, P<0.01).The score of tendon attachment end was positively correlated with CRP (P<0.05). The score of joint capsule effusion in AS patients was positively correlated with BASDAI, BASFI and VAS (P<0.05, P<0.01). The synovial blood flow score was positively correlated with BASDAI, VAS, CRP and ESR (P<0.05, P<0.01). The synovial thickening score was positively correlated with BASDAI, BASFI, VAS, CRP and ESR (P<0.05, P<0.01). There was no correlation between the score of tendon attachment end and BASDAI, BASFI, VAS, CRP and ESR. CONCLUSION: There is a correlation between hip joint ultrasonic score of hip joint and clinical indexes in AS patients.Hip joint capsule score and total ultrasonic score were independent risk factors for hip involvement in AS patients. High frequency ultrasound exhibits clinical value in the diagnosis of hip joint involvement in AS patients.

A Biomechanical Comparison Between the Safety-Squat Bar and Traditional Barbell Back Squat.

ABSTRACT: Johansson, DG, Marchetti, PH, Stecyk, SD, and Flanagan, SP. A biomechanical comparison between the safety-squat bar and traditional barbell back squat. J Strength Cond Res 38(5): 825-834, 2024-The primary objectives for this investigation were to compare the kinematic and kinetic differences between performing a parallel back squat using a traditional barbell (TB) or a safety-squat bar (SSB). Fifteen healthy, recreationally trained male subjects (23 + 4 years of age) performed the back squat with a TB and an SSB at 85% of their respective 1 repetition maximum with each barbell while instrumented for biomechanical analysis. Standard inverse dynamics techniques were used to determine joint kinematic and kinetic measures. A 2 × 3 (exercise × joint) factorial analysis of variance with repeated measures was used to determine the kinetic and kinematic differences between the squats while using the different barbells. Fisher's least significant difference post hoc comparisons showed that the TB resulted in significantly greater maximum hip flexion angle (129.33 ± 11.8° vs. 122.11 ± 12.1°; p < 0.001; d = 1.80), peak hip net joint extensor torque (2.54 ± 0.4 Nm·kg -1 vs. 2.40 ± 0.4 Nm·kg -1 ; p = 0.001; d = 1.10), hip net extensor torque mechanical energy expenditure (MEE; 2.81 ± 0.5 Nm·kg -1 vs. 2.58 ± 0.6 Nm·kg -1 ; p = 0.002; d = 0.97), and ankle net joint plantar flexor torque MEE (0.32 ± 0.09 J·kg -1 vs. 0.28 ± 0.06 J·kg -1 ; p = 0.029; d = 0.63), while also lifting significantly (123.17 ± 20.8 kg vs. 117.17 ± 20.8 kg; p = 0.005; d = 0.858) more weight than the SSB. The SSB resulted in significantly higher maximum knee flexion angles (116.82 ± 5.8° vs. 115.65 ± 5.6°; p = 0.011; d = 0.75) than the TB, with no significant difference in kinetics at the knee. The TB may be preferred to the SSB for developing the hip extensors and lifting higher maximum loads. The SSB may be advantageous in situations where a more upright posture or a lower load is preferred while creating a similar demand for the knee joint.

[Effectiveness analysis of revision surgery after total hip arthroplasty assisted by artificial intelligence preoperative planning system].

Objective: To explore the short-term effectiveness of hip revision surgery guided by artificial intelligence preoperative planning (AIHIP) system. Methods: The clinical data of 22 patients (23 hips) who were admitted between June 2019 and March 2023 and met the selection criteria were retrospectively analyzed. There were 12 males and 10 females with an average age of 69.7 years (range, 44-90 years). There were 19 hips in the first revision, 3 hips in the second revision, and 1 hip in the third revision. The causes of revision included 12 hips with prosthesis loosening, 4 hips with acetabular cup loosening, 3 hips with osteolysis, 2 hips with acetabular dislocation, 1 hip with postoperative infection, and 1 hip with prosthesis wear. There were 6 hips in stage ⅡA, 9 hips in stage ⅡB, 4 hips in stage ⅡC, 3 hips in stage ⅢA, and 1 hip in stage ⅢB according to Paprosky staging of acetabular bone defect. The replacement of prosthesis type, operation time, hospitalization stay, ground active condition, and postoperative infection, fracture, prosthesis loosening, and other adverse events were recorded. The function of the affected limb was evaluated by Harris score before operation, at 1 week and 6 months after operation, and the range of motion of the hip joint was compared before operation and at 6 months after operation. Results: The operation time was 85-510 minutes, with an average of 241.8 minutes; the hospitalization stay was 7-35 days, with an average of 15.2 days; the time of disassociation from the walker was 2-108 days, with an average of 42.2 days. All the 22 patients were followed up 8-53 months (mean, 21.7 months). No adverse events such as prosthesis loosening or infection occurred in the rest of the patients, except for postoperative hematoma of the thigh in 1 patient and dislocation of the hip in 1 hip. The matching degree of acetabular cup was completely matched in 22 hips and mismatched in 1 hip (+2), the matching rate was 95.65%. The matching degree of femoral stem was completely matched in 22 hips and generally matched in 1 hip (-1), and the matching rate was 100%. The Harris scores were 55.3±9.8 and 89.6±7.2 at 1 week and 6 months after operation, respectively, which significantly improved when compared with before operation (33.0±8.6, P<0.05), and further improved at 6 months after operation than at 1 week after operation ( P<0.05). The function of hip joint was evaluated by Harris score at 6 months after operation, and 21 hips were good and 2 hips were moderate, which could meet the needs of daily life. The range of motion of hip joint was (111.09±10.11)° at 6 months after operation, which was significantly different from (79.13±18.50)° before operation ( t=-7.269, P<0.001). Conclusion: AIHIP system can improve the accuracy of revision surgery, reduce the difficulty of surgery, and achieve good postoperative recovery and satisfactory short-term effectiveness.

Accuracy of conventional motion capture in measuring hip joint center location and hip rotations during gait, squat, and step-up activities.

Accurate measurements of hip joint kinematics are essential for improving our understanding of the effects of injury, disease, and surgical intervention on long-term hip joint health. This study assessed the accuracy of conventional motion capture (MoCap) for measuring hip joint center (HJC) location and hip joint angles during gait, squat, and step-up activities while using dynamic biplane radiography (DBR) as the reference standard. Twenty-four young adults performed six trials of treadmill walking, six body-weight squats, and six step-ups within a biplane radiography system. Synchronized biplane radiographs were collected at 50 images per second and MoCap was collected simultaneously at 100 images per second. Bone motion during each activity was determined by matching digitally reconstructed radiographs, created from subject-specific CT-based bone models, to the biplane radiographs using a validated registration process. Errors in estimating HJC location and hip angles using MoCap were quantified by the root mean squared error (RMSE) across all frames of available data. The MoCap error in estimating HJC location was larger during step-up (up to 89.3 mm) than during gait (up to 16.6 mm) or squat (up to 31.4 mm) in all three anatomic directions (all p < 0.001). RMSE in hip joint flexion (7.2°) and abduction (4.3°) during gait was less than during squat (23.8° and 8.9°) and step-up (20.1° and 10.6°) (all p < 0.01). Clinical analysis and computational models that rely on skin-mounted markers to estimate hip kinematics should be interpreted with caution, especially during activities that involve deeper hip flexion.

Comparison of quality and interpretation of newborn ultrasound screening examinations for developmental dysplasia of the hip by basically trained nurses and junior physicians with no previous ultrasound experience.

BACKGROUND: We are obliged to give babies the chance to profit from a nationwide screening of developmental dysplasia of the hip in very rural areas of Mongolia, where trained physicians are scarce. This study aimed to compare the quality and interpretation of hip ultrasound screening examinations performed by nurses and junior physicians. METHODS: A group of 6 nurses and 6 junior physician volunteers with no previous ultrasound experience underwent Graf's standard training in hands-on practice. Newborns were examined before discharge from the hospital, according to the national guideline. Two standard documentation images of each hip were saved digitally. The groups were compared on the proportion of good quality of sonograms and correct interpretation. Two Swiss supervisors' agreed diagnosis according to Graf was considered the final reference for the study purposes. RESULTS: A total of 201 newborns (402 hips or 804 sonograms) were examined in the study, with a mean age of 1.3±0.8 days at examination. Junior physicians examined 100 newborns (200 hips or 400 sonograms), while nurses examined 101 newborns (202 hips or 404 sonograms). The study subjects of the two groups were well balanced for the distribution of baseline characteristics. The study observed no statistically significant difference in the quality of Graf's standard plane images between the providers. Eventually, 92.0% (92) of the physician group and 89.1% (90) of the nurse group were correctly diagnosed as "Group A" (Graf's Type 1 hip) or "Non-Group A" hips (p = 0.484). The most common errors among the groups were a missing lower limb, wrong measurement lines, and technical problems. CONCLUSION: Our study provides evidence that while there might be a trend of slightly more technical mistakes in the nurse group, the overall diagnosis accuracy is similar to junior physicians after receiving standard training in Graf's hip ultrasound method. However, after basic training, regular quality control is a must and all participants should receive refresher trainings. More specifically, nurses need training in the identification of anatomical structures.

Fluoroscopy-guided triple hip block for patients with hip osteoarthritis: A new approach.

Hip osteoarthritis (OA) is found in approximately 10% of the population and often causes disability and social limitations in elderly patients. Intra-articular injections are among the most frequently applied interventional treatments for the hip joint. Femoral and obturator sensorial nerve blocks have also been reported to be effective for both diagnostic and therapeutic purposes. A single needle insertion was performed for the blockage of the hip joint and sensory branches. For the sensory branch of the femoral nerve, the needle is advanced at nearly a 45-degree angle toward below the anterior inferior iliac spine near the anterolateral edge of the hip joint. For the sensory branch of the obturator nerve, the needle is advanced at nearly an angle of 45 degrees toward the area below the junction of the pubis and ischium. Finally, for joint injection, the same needle was advanced toward the midline of the anterior femoral head-neck junction at a steeper angle, and blocks were applied. Three patients with hip osteoarthritis were injected with this method and well-being was achieved in a 3-month follow-up. We think that blockage of the hip joint and peripheral sensory branches with a single needle insertion is a fast and effective method. However, prospective controlled studies are needed to determine the efficacy and safety of the method.

Percutaneous pulsed radiofrequency ablation of articular nerves of the hip joint in patients with chronic hip pain refractory to conventional analgesics.

OBJECTIVES: Total Hip Arthroplasty (THA) may be a risky proposition in patients with comorbidities, and they may require systemic analgesics for chronic hip pain (CHP). Since traditional pain medications may not provide complete pain relief or carry prohibitive adverse effects, pulsed radiofrequency (PRF) treatment of the hip articular nerves (HAN) has been proposed for effective clinical outcomes. We determined the efficacy of PRF-HAN in improvement in CHP compared to baseline pain on conventional systemic analgesics. METHODS: Between August 2015 and December 2021, 31 adult patients with severe comorbid conditions and excruciating chronic hip pain were subjected to a PRF-HAN procedure following a diagnostic block. All 31 patients received PRF of the articular branches of the femoral and obturator nerves. Demographic parameters, numerical rating scale (NRS), Harris Hip Score (HHS), WOMAC scores, the change of these scores from baseline, and any adverse effects were recorded before treatment and on day 1, 1st week, 6 weeks, and 6 months after treatment. RESULTS: All the patients who underwent the PRF-HAN reported a significant improvement in NRS, HHS, and WOMAC scores compared to the baseline values on day 1, at the end of the 1st week, and the 6th week (p<0.001). No adverse events were documented in the study post-procedure until the end of 6 months. CONCLUSION: PRF-HAN is a strong alternative for chronic pain management and augments physical functioning and a return to daily activity in patients who would be deprived of arthroplasty considering associated comorbid conditions.

Experimental assessment of pelvis slipping during postless traction for orthopaedic applications.

BACKGROUND: The application of lower limb traction during hip arthroscopy and femur fractures osteosynthesis is commonplace in orthopaedic surgeries. Traditional methods utilize a perineal post on a traction table, leading to soft tissue damage and nerve neuropraxia. A postless technique, using high-friction pads, has been considered as a potential damage-free alternative. However, whether these pads sufficiently prevent patient displacement remains unknown. Thus, this study systematically assesses the efficacy of commercial high-friction pads (PinkPad and CarePad) in restraining subject displacement, for progressively increasing traction loads and different Trendelenburg angles. METHODS: Three healthy male subjects were recruited and tested in supine and Trendelenburg positions (5° and 10°), using a customized boot-pulley system. Ten load disks (5 kg) were dropped at 15s intervals, increasing gradually the traction load up to 50 kg. Pelvis displacement along the traction direction was measured with a motion capture system. The displacement at 50 kg of traction load was analyzed and compared across various pads and bed inclinations. Response to varying traction loads was statistically assessed with a quadratic function model. RESULTS: Pelvis displacement at 50 kg traction load was below 60 mm for all conditions. Comparing PinkPad and CarePad, no significant differences in displacement were observed. Finally, similar displacements were observed for the supine and Trendelenburg positions. CONCLUSIONS: Both PinkPad and CarePad exhibited nearly linear behavior under increasing traction loads, limiting displacement to 60 mm at most for 50 kg loads. Contrary to expectations, placing subjects in the Trendelenburg position did not increase adhesion.

Sex-based differences in neck selectivity in total hip arthroplasty using a modular femoral neck system.

BACKGROUND: Dislocation is a major complication of total hip arthroplasty (THA). The modular femoral neck system provides practical advantages by allowing adjustment of neck version and length in the presence of intraoperative instability. Anatomical studies have identified morphological differences in the hip joint between men and women. Despite sex-based differences in hip morphology, it remains unclear whether such differences affect neck selectivity in THA using a modular neck system and whether this approach achieves anatomical reconstruction, thereby reducing complications such as dislocation. This study aimed to investigate gender differences in neck selectivity in THA with the modular neck system and assess the clinical impact of the modular neck system. METHODS: A total of 163 THAs using a modular neck system were included in this study. Data on the type of modular neck and intraoperative range of motion (ROM) were retrieved from patient records. Pre- and post-operative leg length differences (LLD) were examined as part of the radiographic assessment. Dislocation was investigated as a postoperative complication. RESULTS: Neck selectivity did not significantly differ between men and women. The comparison of pre- and post-operative LLD revealed a tendency for varus necks to improve LLD more than version-controlled necks. Furthermore, no significant correlation was found between intraoperative ROM and neck selectivity, or postoperative dislocation and neck selectivity. CONCLUSIONS: This study on THA with a modular neck system provided valuable insights into sex-based differences in neck selectivity and highlighted the potential benefits of the modular neck system in addressing LLD and preventing postoperative dislocation.

Wearing a back-support exoskeleton alters lower-limb joint kinetics during single-step recovery following a forward loss of balance.

We assessed the effects of a passive, back-support exoskeleton (BSE) on lower-limb joint kinetics during the initiation and swing phases of recovery from a forward loss of balance. Sixteen (8M, 8F) young, healthy participants were released from static forward-leaning postures and attempted to recover their balance with a single-step while wearing a BSE (backXTM) with different levels of support torque and in a control condition. The BSE provided âˆ¼ 15-20 Nm of external hip extension torque on the stepping leg at the end of initiation and beginning of swing phases. Participants were unable to generate sufficient hip flexion torque, power, and work to counteract this external torque, although they sustained hip flexion torque for a more prolonged period, resulting in slightly increased hip contribution to positive leg work (compared to control). However, net positive leg work, and the net contribution of hip joint (human + BSE) to total leg work decreased with BSE use. While all participants had changes in hip joint kinetics, a significant compensatory increase in ankle contribution to positive leg work was observed only among females. Our results suggest that BSE use adversely affects reactive stepping by decreasing the stepping leg kinetic energy for forward propulsion, and that the relative contributions of lower-limb joints to total mechanical work done during balance recovery are altered by BSE use. BSEs may thus need to be implemented with caution for dynamic tasks in occupational settings, as they may impair balance recovery following a forward loss of balance.

Association Between Chondrolabral Junction Breakdown and Conversion to Total Hip Arthroplasty After Hip Arthroscopy for Symptomatic Labral Tears: Minimum 8-Year Follow-up.

BACKGROUND: Arthroscopic treatment of femoroacetabular impingement (FAI) and symptomatic labral tears confers short- to midterm benefits, yet further long-term evidence is needed. Moreover, despite the physiological and biomechanical significance of the chondrolabral junction (CLJ), the clinical implications of damage to this transition zone remain understudied. PURPOSE: To (1) report minimum 8-year survivorship and patient-reported outcome measures after hip arthroscopy for FAI and (2) characterize associations between outcomes and patient characteristics (age, body mass index, sex), pathological parameters (Tönnis angle, alpha angle, type of FAI, CLJ breakdown), and procedures performed (labral management, FAI treatment, microfracture). STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: This retrospective cohort study included patients who underwent primary hip arthroscopy for symptomatic labral tears secondary to FAI by a single surgeon between 2002 and 2013. All patients were ≥18 years of age with minimum 8-year follow-up and available preoperative radiographs. The primary outcome was conversion to total hip arthroplasty (THA), and secondary outcomes included revision arthroscopy, patient-reported outcome measures, and patient satisfaction. CLJ breakdown was assessed using the Beck classification. Kaplan-Meier estimates and weighted Cox regression were used to estimate 10-year survivorship (no conversion to THA) and identify risk factors associated with THA conversion. RESULTS: In this study of 174 hips (50.6% female; mean age, 37.8 ± 11.2 years) with mean follow-up of 11.1 ± 2.5 years, the 10-year survivorship rate was 81.6% (95% CI, 75.9%-87.7%). Conversion to THA occurred at a mean 4.7 ± 3.8 years postoperatively. Unadjusted analyses revealed several variables significantly associated with THA conversion, including older age; higher body mass index; higher Tönnis grade; labral debridement; and advanced breakdown of the CLJ, labrum, or articular cartilage. Survivorship at 10 years was inferior in patients exhibiting severe (43.6%; 95% CI, 31.9%-59.7%) versus mild (97.9%; 95% CI, 95.1%-100%) breakdown of the CLJ (P < .001). Multivariable analysis identified worsening CLJ breakdown (weighted hazard ratio per 1-unit increase, 6.41; 95% CI, 3.11-13.24), older age (1.09; 95% CI, 1.04-1.14), and higher Tönnis grade (4.59; 95% CI, 2.13-9.90) as independent negative prognosticators (P < .001 for all). CONCLUSION: Although most patients achieved favorable minimum 8-year outcomes, several pre- and intraoperative factors were associated with THA conversion; of these, worse CLJ breakdown, higher Tönnis grade, and older age were the strongest predictors.

Efficient hip joint distraction using the AO large femoral distractor in treating acetabular fractures associated with marginal impaction and intraarticular incarcerated fragments.

PURPOSE: The results after acetabular fracture are primarily related to the quality of articular reduction. Using the AO large femoral distractor, incarcerated fragments can be easily removed, and marginally impacted fragments can be elevated under direct visualization without further re-dislocating the joint. The current study aimed to evaluate our early results of using the AO large femoral distractor as an assisting tool during ORIF of acetabular fractures associated with marginal impaction or intraarticular incarcerated fragments. METHODS: Eighteen patients were included in this retrospective case series study diagnosed with an acetabular fracture associated with either marginal impaction injury or an intraarticular incarcerated fragment. On a usual operative table, all patients were operated upon in a prone position through the Kocher Langenbeck approach. The AO large femoral distractor was used to facilitate hip joint distraction. Postoperative fracture reduction and joint clearance were assessed in the immediate postoperative CT scans. RESULTS: The average age of the patients was 30 ± 8.2 years; 13 (72.2%) were males. All cases had a posterior wall fracture, and it was associated with transverse fractures, posterior column fractures, and T-type fractures in five (27.8%), two (11.1%), and one (5.6%) patients, respectively. Intraarticular incarcerated fragments were present in 13 (72.2%) cases and marginal impaction in five (27.8%). Fracture reduction measured on the postoperative CT scans showed an anatomical reduction in 14 (77.8%) patients, imperfect in four (22.2%), and complete clearance of the hip joint of any incarcerated fragments. CONCLUSION: The use of the AO large femoral distractor is a reliable and reproducible technique that can be applied to assist in the removal of incarcerated intraarticular fragments and to ease the reduction of marginally impacted injuries associated with acetabular fractures.

Unveiling the learning curve of periacetabular osteotomy.

Aims: Periacetabular osteotomy (PAO) is widely recognized as a demanding surgical procedure for acetabular reorientation. Reports about the learning curve have primarily focused on complication rates during the initial learning phase. Therefore, our aim was to assess the PAO learning curve from an analytical perspective by determining the number of PAOs required for the duration of surgery to plateau and the accuracy to improve. Methods: The study included 118 consecutive PAOs in 106 patients. Of these, 28 were male (23.7%) and 90 were female (76.3%). The primary endpoint was surgical time. Secondary outcome measures included radiological parameters. Cumulative summation analysis was used to determine changes in surgical duration. A multivariate linear regression model was used to identify independent factors influencing surgical time. Results: The learning curve in this series was 26 PAOs in a period of six months. After 26 PAO procedures, a significant drop in surgical time was observed and a plateau was also achieved. The mean duration of surgery during the learning curve was 103.8 minutes (SD 33.2), and 69.7 minutes (SD 18.6) thereafter (p < 0.001). Radiological correction of acetabular retroversion showed a significant improvement after having performed a total of 93 PAOs, including anteverting PAOs on 35 hips with a retroverted acetabular morphology (p = 0.005). Several factors were identified as independent variables influencing duration of surgery, including patient weight (ß = 0.5 (95% confidence interval (CI) 0.2 to 0.7); p < 0.001), learning curve procedure phase of 26 procedures (ß = 34.0 (95% CI 24.3 to 43.8); p < 0.001), and the degree of lateral correction expressed as the change in the lateral centre-edge angle (ß = 0.7 (95% CI 0.001 to 1.3); p = 0.048). Conclusion: The learning curve for PAO surgery requires extensive surgical training at a high-volume centre, with a minimum of 50 PAOs per surgeon per year. This study defined a cut-off value of 26 PAO procedures, after which a significant drop in surgical duration occurred. Furthermore, it was observed that a retroverted morphology of the acetabulum required a greater number of procedures to acquire proficiency in consistently eliminating the crossover sign. These findings are relevant for fellows and fellowship programme directors in establishing the extent of training required to impart competence in PAO.

[Correlation analysis between combined deflection angle and osteonecrosis of femoral head after femoral neck fracture].

Objective: To evaluate the correlation between pelvic incidence (PI) angle, hip deflection angle (HDA), combined deflection angle (CDA) and osteonecrosis of the femoral head (ONFH) after femoral neck fracture, in order to explore early predictive indicators for ONFH occurrence after femoral neck fracture. Methods: A study was conducted on patients with femoral neck fractures who underwent cannulated screw internal fixation between December 2018 and December 2020. Among them, 208 patients met the selection criteria and were included in the study. According to the occurrence of ONFH, the patients were allocated into ONFH group and non-NOFH group. PI, HDA, and CDA were measured based on the anteroposterior X-ray films of pelvis and axial X-ray films of the affected hip joint before operation, and the differences between the two groups were compared. The receiver operating characteristic curve (ROC) was used to evaluate the value of the above imaging indicators in predicting the occurrence of ONFH. Results: Among the 208 patients included in the study, 84 patients experienced ONFH during follow-up (ONFH group) and 124 patients did not experience ONFH (non-ONFH group). In the non-ONFH group, there were 59 males and 65 females, the age was 18-86 years (mean, 53.9 years), and the follow-up time was 18-50 months (mean, 33.2 months). In the ONFH group, there were 37 males and 47 females, the age was 18-76 years (mean, 51.6 years), and the follow-up time was 8-45 months (mean, 22.1 months). The PI, HDA, and CDA were significantly larger in the ONFH group than in the non-ONFH group ( P<0.05). ROC curve analysis showed that the critical value of PI was 19.82° (sensitivity of 40.5%, specificity of 86.3%, P<0.05); the critical value of HDA was 20.94° (sensitivity of 77.4%, specificity of 75.8%, P<0.05); and the critical value of CDA was 39.16° (sensitivity of 89.3%, specificity of 83.1%, P<0.05). Conclusion: There is a correlation between PI, HDA, CDA and the occurrence of ONFH after femoral neck fracture, in which CDA can be used as an important reference indicator. Patients with CDA≥39.16° have a higher risk of ONFH after femoral neck fracture.

Neonatal Ultrasound and Radiographic Markers of Hip Dysplasia in Young Adults.

OBJECTIVES: To examine radiologic outcomes at skeletal maturity of sonographically normal, immature, mildly, and severely dysplastic newborn hips. METHODS: During 1988 to 1990, 11 925 newborns were enrolled in a randomized controlled trial examining screening strategies for developmental hip dysplasia. In total, 4469 were invited to clinical and radiologic follow-up 18 years later, of which 1735 had received neonatal ultrasound. Radiographic markers for dysplasia in left adult hips included the center-edge (CE) angle. RESULTS: At follow-up, 984 of 1735 (56.7%) with newborn ultrasound met, of which 966 (614 females) had valid radiographs and were thus included. For females, 34 (10.2%) and 1 (0.3%) of the 332 sonographically normal left neonatal hips were judged borderline (20°≤ CE <25°) or dysplastic (CE <20°) at skeletal maturity respectively. Corresponding numbers were 36 (19.7%) and 3 (1.6%) of the 183 immature, 12 (15.6%) and 2 (2.6%) of the 77 mildly dysplastic, and 3 (13.6%) and 3 (13.6%) of the 22 severely dysplastic neonatal left hips (P ≤ .001). In males, no associations were found. In females, adult joint hypermobility was associated with sonographic neonatal hip instability (P = .046), as well as with adult acetabular dysplasia (P = .024). CONCLUSIONS: Significant associations between neonatal hip phenotypes and adult dysplasia were revealed in females. This indicates the possibility of different mechanisms affecting the course of developmental dysplasia of the hip for females and males, prompting consideration of prolonged clinical and radiologic follow-up for females with dysplastic neonatal hips. Results in males are limited by low numbers of dysplastic hips. The significance of joint hypermobility warrants further investigation.

Modern Hip Arthroscopy for FAIS May Delay the Natural History of Osteoarthritis in 25% of Patients: A 12-Year Follow-up Analysis.

BACKGROUND: Little is known about the effect of modern hip arthroscopy on the natural history of femoroacetabular impingement syndrome (FAIS) with respect to joint preservation. PURPOSE: To (1) characterize the natural history of FAIS and (2) understand the effect of modern hip arthroscopy by radiographically comparing the hips of patients who underwent only unilateral primary hip arthroscopy with a minimum follow-up of 10 years. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Between 2010 and 2012, 619 consecutive patients were reviewed from the practice of a single fellowship-trained hip arthroscopic surgeon. Inclusion criteria were FAIS, bilateral radiographic findings of femoroacetabular impingement, primary unilateral hip arthroscopy (labral repair, femoroplasty, or capsular closure), and minimum 10-year follow-up. The preoperative and minimum 10-year postoperative radiographs of patients were evaluated at each time point. Both operative and nonoperative hips were graded using the Tönnis classification or the presence of hip arthroplasty by 2 independent reviewers. Subgroup analyses were performed. RESULTS: A total of 200 hips from 100 patients were evaluated at a mean follow-up of 12.0 years. Preoperatively, 98% and 99% of operative and nonoperative hips were evaluated as Tönnis grades 0 and 1, respectively; 5% of nonoperative hips had worse Tönnis grades than operative hips. The nonoperative hip advanced to a worse Tönnis grade in 48% (48/100) of cases compared with 28% (28/100) among operative hips. At follow-up, Tönnis grades between hips were equal in 70% (70/100) of the cases, the operative hip had a better grade 25% (25/100) of the time, and the nonoperative hip had a better grade 5% (5/100) of the time. Modern hip arthroscopy was associated with a relative risk reduction of 42% in osteoarthritis progression. Impingement with borderline dysplasia, age, preoperative Tönnis grade, and alpha angle >65° were key risk factors in the radiographic progression of osteoarthritis. CONCLUSION: Although the majority of patients (70%) undergoing hip arthroscopy for FAIS did not experience differences between operative and nonoperative hips in terms of the radiographic progression of osteoarthritis, the natural history may be favorably altered for 25% of patients whose Tönnis grade was better after undergoing arthroscopic correction. Modern hip arthroscopy indications and techniques represent a valid joint-preservation procedure conferring a relative risk reduction of 42% in the progression of osteoarthritis. Arthroscopy for mixed patterns of impingement and instability were the fastest to degenerate.

Long-term Outcomes of Primary Hip Arthroscopy: Multicenter Analysis at Minimum 10-Year Follow-up With Attention to Labral and Capsular Management.

BACKGROUND: Hip arthroscopy is rapidly advancing, with positive published outcomes at short- and midterm follow-up; however, available long-term data remain limited. PURPOSE: To evaluate outcomes of primary hip arthroscopy at a minimum 10-year follow-up at 2 academic centers by describing patient-reported outcomes and determining reoperation and total hip arthroplasty (THA) rates. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Patients with primary hip arthroscopy performed between January 1988 and April 2013 at 2 academic centers were evaluated for postoperative patient-reported outcomes-including the visual analog scale, Tegner Activity Scale score, Hip Outcome Score Activities of Daily Living and Sport Specific subscales, modified Harris Hip Score, Nonarthritic Hip Score, 12-item International Hip Outcome Tool, surgery satisfaction, and reoperations. RESULTS: A total of 294 patients undergoing primary hip arthroscopy (age, 40 ± 14 years; 66% women; body mass index, 27 ± 6) were followed for 12 ± 3 years (range, 10-24 years) postoperatively. Labral debridement and repair were performed in 41% and 59% of patients, respectively. Of all patients who underwent interportal capsulotomy, 2% were extended to a T-capsulotomy, and 11% underwent capsular repair. At final follow-up, patients reported a mean visual analog scale at rest of 2 ± 2 and with use of 3 ± 3, a 12-item International Hip Outcome Tool of 68 ± 27, a Nonarthritic Hip Score of 81 ± 18, a modified Harris Hip Score of 79 ± 17, and a Hip Outcome Score Activities of Daily Living of 82 ± 19 and Sport Specific subscale of 74 ± 25. The mean surgical satisfaction was 8.4 ± 2.4 on a 10-point scale, with 10 representing the highest level of satisfaction. In total, 96 hips (33%) underwent reoperation-including 65 hips (22%) converting to THA. THA risk factors included older age, higher body mass index, lower lateral center-edge angle, larger alpha angle, higher preoperative Tönnis grade, as well as labral debridement and capsular nonrepair (P≤ .039). Patients undergoing combined labral and capsular repair demonstrated a THA conversion rate of 3% compared with 31% for patients undergoing combined labral debridement and capsular nonrepair (P = .006). Labral repair trended toward increased 10-year THA-free survival (84% vs 77%; P = .085), while capsular repair demonstrated significantly increased 10-year THA-free survival (97% vs 79%; P = .033). CONCLUSION: At a minimum 10-year follow-up, patients undergoing primary hip arthroscopy demonstrated high satisfaction and acceptable outcome scores. In total, 33% of patients underwent reoperation-including 22% who underwent THA. Conversion to THA was associated with patient factors including older age, higher Tönnis grade, and potentially modifiable surgical factors such as labral debridement and capsular nonrepair.

Calipered kinematic alignment restored the arithmetic hip-knee-ankle angle, achieved high satisfaction and improved clinical outcomes.

PURPOSE: The purpose of this study was to determine whether unrestricted calipered kinematic alignment (KA), coupled with a medial-stabilised (MS) implant system, can reproduce the patient's constitutional alignment as per the arithmetic hip-knee-ankle (aHKA) and improve clinical outcomes. METHODS: One-hundred and ninety-three patients received total knee arthroplasty by the senior author. To determine whether the constitutional alignment was achieved, the postoperative hip-knee-ankle (HKA) alignment was compared against the aHKA. Range of motion (ROM) was determined preoperative and postoperatively at 6 months and 2 years by measuring the active flexion and extension. Patient-Reported Outcomes Measures (PROMs) including Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome Score (KOOS), Forgotten Joint Score (FJS) and Visual Analogue Scale for Satisfaction were also completed. The Sports and Recreation component of KOOS was used to assess the patient's ability to return to sports and daily activities. RESULTS: There was a strong correlation between postoperative HKA and aHKA (r = 0.7, p < 0.05). There was a significant improvement in both extension and flexion seen from as early as 6 months postoperatively, with a mean flexion of 123° ± 11° and extension of 1° ± 3° at 2 years. PROMs had significant improvements with a mean score of 42.8 ± 6.0 for the OKS and all KOOS subscales consisting of Symptoms (88.0 ± 11.7), Pain (91.4 ± 11.6), Activities of Daily Living (91.1 ± 12.4), Sports (76.8 ± 22.1) and Quality of Life (83.0 ± 19.1). The FJS had significant improvements from 6 months to 2 years of 19.9 (p < 0.05), with a mean score of 69.2 ± 26.6 at 2 years. Ninety-three percent (180 patients) were classified as 'satisfied' at the 2-year timepoint. The KOOS Sports component was completed by 64% (124 patients), whereby the mean age was younger than the noncompliant patients (67.7 ± 9.4 vs. 71.7 ± 8.2 years). CONCLUSION: Unrestricted calipered KA can result in an alignment that closely resembles the patient's constitutional alignment, as per the aHKA. This resulted in improved knee ROM and patient satisfaction, as well as assisting younger patients to return to sports and daily activities. LEVEL OF EVIDENCE: Level IV.

The effect of marathon running on the lower extremity kinematics and muscle activities during walking and running tasks.

Patellofemoral pain syndrome (PFPS) is a common injury among runners, and it is thought that abnormal lower extremity biomechanics contribute to its development. However, the relationship between biomechanical changes after a marathon and PFPS injury remains limited. This study aims to investigate whether differences in knee and hip kinematics and lower extremity muscle activities exist in recreational runners before and after a marathon. Additionally, it aims to explore the relationship between these biomechanical changes and the development of PFPS injury. 12 recreational runners participated in the study. Kinematics and muscle activities of the lower extremity were recorded during walking (5 km/h) and running (10 km/h) tasks within 24 hours before and within 5 hours after a marathon. After the marathon, there was a significant decrease in peak knee flexion (walking: p = 0.006; running: p = 0.006) and an increase in peak hip internal rotation (walking: p = 0.026; running: p = 0.015) during the stance phase of both walking and running compared to before the marathon. The study demonstrates a decrease in knee flexion and an increase in hip internal rotation during the stance phase of gait tasks after completing a marathon, which may increase the risk of developing PFPS injury.