Ligament strain on the iliofemoral, pubofemoral, and ischiofemoral ligaments in cadaver specimens: Biomechanical measurement and anatomical observation

Specimen-specific finite element representations of implanted hip capsules

The hip capsule is a ligamentous structure that contributes to hip stability. This article developed specimen-specific finite element models that replicated internal-external (I-E) laxity for ten implanted hip capsules. Capsule properties were calibrated to minimize root mean square error (RMSE) between model and experimental torques. RMSE across specimens was 1.02 ± 0.21 Nm for I-E laxity and 0.78 ± 0.33 Nm and 1.10 ± 0.48 Nm during anterior and posterior dislocation, respectively. RMSE for the same models with average capsule properties was 2.39 ± 0.68 Nm. Specimen-specific models demonstrated the importance of capsule tensioning in hip stability and have relevance for surgical planning and evaluation of implant designs.

Changes Over Time in the Strain on the Inferior Iliofemoral Ligament During a Sustained 5-Minute High-Force Long-Axis Distraction Mobilization: A Cadaveric Study

OBJECTIVE

To analyze the changes over time in the strain on the inferior iliofemoral (IIF) ligament when a constant high-force long-axis distraction mobilization (LADM) was applied over 5 minutes.

DESIGN

A cross-sectional laboratory cadaveric study.

SETTING

Anatomy laboratory.

PARTICIPANTS

Thirteen hip joints from 9 fresh-frozen cadavers (mean age, 75.6±7.8 years; N=13).

INTERVENTIONS

High-force LADM in open-packed position was sustained for a period of 5 minutes.

MAIN OUTCOME MEASURE(S)

Strain on IFF ligament was measured over time with a microminiature differential variable reluctance transducer. Strain measurements were taken at every 15 seconds for the first 3 minutes and every 30 seconds for the next 2 minutes.

RESULTS

Major changes in strain occurred in the first minute of high-force LADM application. The greatest increase in strain on the IFF ligament occurred at the first 15 seconds (7.3±7.2%). At 30 seconds, the increase in strain was 10.1±9.6%, the half of the total increase at the end of the 5-minute high-force LADM (20.2±8.5%). Significant changes in strain measures were shown to occur at 45 seconds of high-force LADM (F=18.11; P<.001).

CONCLUSIONS

When a 5-minute high-force LADM was applied, the major changes in the strain on IIF ligament occurred in the first minute of the mobilization. A high-force LADM mobilization should be sustained at least 45 seconds to produce a significant change in the strain of capsular-ligament tissue.

Differentiation of strains in the lateral and medial bands of the iliofemoral ligament: A segmental approach

Iliofemoral ligament strains have been assessed in a circumscribed portion, limiting the information regarding the strains in the proximal, mid and distal portions. The purpose of this study is to describe the longitudinal and transversal strain within the proximal, mid and distal portions of the lateral and medial bands of the iliofemoral ligament. Ten fresh cadaveric specimens were assessed. The iliofemoral ligaments were divided into medial and lateral bands. Hemispherical beads (2.6 mm) were placed on the lateral and medial borders of each band. Four positions were assessed: abduction, extension, internal and external rotations combined with extension. The hemispherical beads were scanned at the end range of motion using a laser scanner. The three-dimensional position of each bead was used to estimate longitudinal and transversal strains. A three-factor ANOVA was used to compare movements, borders, and portions within each ligament for longitudinal strains. A one-way ANOVA was used to compare transversal strains between portions. This technique showed mean reliability (ICC: 2, 1) of 0.90 ± 0.06. The external rotation showed the highest strains in both ligaments (p < 0.05). Abduction showed a significant difference between the lateral and medial borders in both bands (p = 0.001). Eight movement-border combinations showed a significant difference between proximal, medial, and lateral portions (p < 0.005). According to our results, there is a clear effect of portions (proximal, mid and distal) within the ligament and movements. Abduction shows the lowest strains longitudinally but the largest strains transversally. Although we do not know the impact of this phenomenon, future studies should assess the strains following hip arthroscopies. The latter might improve the impact of this procedure on hip biomechanics. Lastly, the iliofemoral ligament should be assessed using a segmental approach rather than as a complete unit.

The anatomy of the hindlimb of Theropithecus brumpti (Cercopithecidae, Papionini): Morphofunctional implications

Theropithecus brumpti is a primate known from numerous craniodental specimens in the Plio-Pleistocene Shungura Formation (Lower Omo Valley, Ethiopia), but the anatomy of its hindlimb is documented only by a few associated and mostly incomplete postcranial specimens. The adaptations of T. brumpti are still debated, with its substrate preferences and its use of squatting postures recently discussed based on anatomical differences when compared with its extant representative, Theropithecus gelada. Here, we describe an associated femur and tibia (L 869-1 and L 869-2) of a presumed T. brumpti male and a partial foot (L 865-1r and L 865-1t) of a male T. brumpti, dated to ca. 2.6 Ma and ca. 2.32 Ma respectively. Based on univariate and bivariate morphometric analyses, we provide new data on the morphological correlates of substrate preferences and postural behaviors of this fossil species. Our results are in agreement with previous analyses and present T. brumpti as a predominantly terrestrial primate. We demonstrate the presence of osteological correlates associated with the use of squatting behaviors in T. brumpti but also point to significant anatomical differences between this paleontological species and T. gelada. These differences blur the functional value of characters previously identified as diagnostic of T. gelada and its postural behavior. We further document the postcranial distinctiveness of the Theropithecus clade in relation to the Papio clade. This study thus provides new insights into the postcranial anatomy and paleoecology of an abundant fossil primate from the Plio-Pleistocene of eastern Africa.

Ilio-femoral ligament strains during the flexion-abduction-external rotation test: A cadaveric study

BACKGROUND

Flexion-abduction-external-rotation (FABER) test is one of the most used tests during the clinical assessment of the hip joint. The limited range of motions reached could be due to iliofemoral ligament tightness, but no study has assessed capsular ligament strain during this test. The main objective of this study is to report strains within the iliofemoral ligament during the FABER test using a segmental approach.

METHODS

9 hips were harvested, and all muscles were removed. Hemispherical markers (∅ 2.6 mm) were glued on the lateral and medial borders of both the medial and lateral iliofemoral bands, separating each border into proximal, mid, and distal portions. The lower limb was placed in a FABER test position. A laser scanner allowed to digitize the 3D surface of the capsule. A Kruskal-Wallis test was performed to assess the effect of ligaments, borders, and portions.

FINDINGS

The lateral band of the iliofemoral ligament showed greater strains (14.6 ± 11.4%) compared to the medial band (-8.7 ± 14.2%) (p < 0.001). The greatest strains were observed in the distal portion of the lateral border of the lateral band (51.1 ± 21.5%). A decrease in strain was observed in the mid-portion of the medial border of the medial iliofemoral ligament (-27.9 ± 8.9%).

INTERPRETATION

The FABER test is used to assess pain at the hip. Our results show that the limited range of motion at the hip during this test might be caused by increased strains in the lateral band. These results demonstrate that a limitation of joint range of motion during the FABER could be due to an excessive tension of the lateral band of the iliofemoral ligament.

Contributions of the ischiofemoral ligament, iliofemoral ligament, and conjoined tendon to hip stability after total hip arthroplasty: A cadaveric study

An adequate soft tissue balance is important in total hip arthroplasty (THA). This study assessed the contribution of the iliofemoral ligament, ischiofemoral ligament, and conjoined tendon to the range of hip rotation after THA and hip stability in response to axial traction. THA was performed in eight fresh-frozen cadaveric specimens via an anterolateral approach using a navigation system. The ischiofemoral ligament, the medial arm of the iliofemoral ligament, and the conjoined tendon were resected in that order. The ranges of external and internal rotation and the amount of movement of the femoral head in response to axial traction were measured with the hip in 10° of extension, the neutral position, and in 10°, 30°, and 60° of flexion. Resection of the medial arm of the iliofemoral ligament significantly increased the range of external rotation in 10° of extension, the neutral position, and in 10°, 30°, and 60° of flexion. The conjoined tendon was the most important inhibitor of internal rotation from 10° of extension to 30° of flexion. Although each single element had a minor role in stabilizing the hip when axial traction was applied, resection of two or more elements significantly affected joint stability. The iliofemoral ligament and conjoined tendon are the main inhibitors of external rotation and internal rotation, respectively, when THA is performed using an anterior or anterolateral approach. Resection of two or more elements could greatly affect hip stability when axial traction is applied.

Impact of Capsulotomy on Hip Biomechanics during Arthroscopy

Background and Objectives: Anterior capsulotomy is routinely performed in hip arthroscopy to improve joint visualization; however, this can partly or completely disrupt the stabilizing ligaments of the hip. This study aimed to report the effects of conventional and extensive arthroscopic capsulotomies on hip stability. Materials and Methods: Eight freshly frozen cadaveric pelvises were used in this study. The range of motion and translation were measured and compared among different capsular conditions utilized in hip arthroscopy, with a special interest in the iliofemoral ligament (IFL) and zona orbicularis (ZO). The conditions included intact capsule, interportal capsulotomy, T-capsulotomy, complete IFL disruption, and complete IFL and ZO disruption. Internal rotation at three flexion planes (−10°, 0°, and 30°) and external rotation at six flexion planes (−10°, 0°, 30°, 60°, 90°, and 110°) were measured with corresponding femoral head translation distance at the application of 2.5 Nm torque. Results: As compared to an intact capsule, a significant increase in external rotation was observed after interportal capsulotomy from −10° to 60° and after T-capsulotomy from −10° to 110° flexion. A significant translation was observed only with a T-capsulotomy, which ranged from 1.9 to 2.3 mm across the flexion angles. Compared with conventional interportal capsulotomy, disruption of the entire IFL resulted in a significant increase in external rotation in all flexion planes, and significant translation was accompanied by disruption of the ZO. Conclusions: Interportal capsulotomy can result in an increase in range of motion, and T-capsulotomy can lead to significant translation. Partial or complete tears of the IFL and ZO can result in further external rotation and translation.

The intraoperative hip range of motion in total hip arthroplasty predicts postoperative patient's satisfaction for cutting toenails and putting on sock

BACKGROUND

Restricted hip range of motion (ROM) has been proposed as a useful diagnostic tool for osteoarthritis. The relations between the intraoperative hip ROM under anesthesia in total hip arthroplasty (THA) and recovery of clinical mobility outcomes were unclear. This study evaluated the association between the intraoperative hip ROM under anesthesia in THA and the postoperative recovery of clinical mobility, including cutting toenails and putting on socks after THA.

METHODS

The study was performed as a prospective cohort study and included 93 hips in 85 patients who underwent primary anterior-based muscle-sparing THA in the supine position. The hip ROM was evaluated under anesthesia before skin incision and intraoperative stability test. The Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire (JHEQ) was evaluated. A questionnaire on whether and how patients could cut toenails and putting on socks was assessed. The relationship between hip ROM at intraoperative stability tests and JHEQ moving score, cutting toenails, and putting on socks scores were evaluated statistically.

RESULTS

We observed a week positive correlation between intraoperative hip ROM and the total of JHEQ mobility score. A moderate positive correlation was observed between external rotation angle with flexion 90°and cutting toenails and putting on socks score oh JHEQ. 94.6% and 96.8% of the patients could cut their toenails and putting on socks by themselves after surgery. The optimum cutoff range for high patient satisfaction for putting on socks and cutting toenails was 110° for flexion and 35°-40° for the external rotation angle in the intraoperative stability test.

CONCLUSION

Hip ROM during intraoperative stability testing, especially the external rotation angle can predict postoperative outcomes and patient satisfaction for cutting toenails and putting on socks. We suggested that the capsule or capsular ligament release around the hip was increased to provide sufficient ROM without compromising stability.

An Anatomic Study of the Relationship Between the Iliocapsularis Muscle and Iliofemoral Ligament in Total Hip Arthroplasty

Background

The preservation of soft tissues is an important factor for preventing dislocation after total hip arthroplasty. Anatomical studies have revealed that the inferior iliofemoral ligament (ILFL) contributes significantly to the native stability of the hip. This study aimed to investigate the anatomical structures of the iliocapsularis muscle (ICM) and ILFL from a surgical perspective.

Methods

In total, we assessed 50 hip specimens from 25 embalmed cadavers. The size and location of ICM and ILFL (at the upper, middle, and lower parts of the femoral head) were assessed in a neutral position. The ratio of ICM and ILFL widths to the femoral head was evaluated.

Results

The mean ICM and ILFL widths were 7.5 and 14.6, 12.0 and 14.2, and 12.8 and 15.2 mm at the upper, middle, and lower levels, respectively. The mean ICM thicknesses were 1.3, 9.0, and 9.1 mm at the upper, middle, and lower levels, respectively. The distributions of ICM and ILFL from the lateral edge of the femoral head were 21.1%–37.4% and 4.9%–36.5%, 9.5%–35.6% and 7.9%–38.7%, and 11.0%–38.7% and 9.5%–42.4% at the upper, middle, and lower levels, respectively.

Conclusion

ICM and ILFL were located at the anterolateral side of the femoral head, and the medial edge of the ILFL corresponded to that of the ICM. ICM can serve as a landmark for preserving ILFL in total hip arthroplasty using the anterior approach.

Is there enough evidence to support hip capsular reconstruction? A systematic review of biomechanical studies

The aim of this study was to review and summarize the available biomechanical data on hip capsular reconstruction to guide clinical decision-making. A literature search was completed in December 2020 using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify biomechanical cadaver studies on hip capsular reconstruction, hip capsulectomy or hip capsular defect. The investigated parameters included maximum distraction force, capsular state affecting range of motion (ROM), rotation and translation. Four studies met al. the inclusion–exclusion criteria. The median effective force for resisting maximum distraction for the reconstruction state, capsular defect state and the intact state was 171, 111 and 206 N, respectively. The defect capsule force was significantly lower (P = 0.00438) than the intact capsule force. The reconstruction state had a higher distraction force than that of the capsular defect, but due to heterogeneity, the overall effect size was not statistically significant. The capsular reconstruction state reduced excess motion and the degree of instability compared to the capsular defect state but restored the hip close to its native capsular state in the cadaveric model. When compared to capsulectomy/defect state, hip capsular reconstruction significantly improved the rotational stability and effective force at maximum distraction and minimized translation. However, no conclusions can be made regarding the most effective protocol due to the high heterogeneity between the four studies. Further biomechanical studies are needed to test various types of grafts under the same protocol.

The role of the iliofemoral ligament as a stabilizer of the hip joint

The purpose of this systematic literature review is to analyse the role of the iliofemoral ligament (ILFL) as a hip joint stabilizer in the current literature.

A total of 26 articles were included in the review. The ILFL is the largest hip ligament consisting of two distinct arms and is highly variable, both in its location and overall size, and plays a primary role in hip stability; in the case of hip dislocation, the iliofemoral ligament tear does not heal, resulting in a persistent anterior capsule defect. Clinically, the ILFL is felt to limit external rotation in flexion and both internal and external rotation in extension.

The abduction–hyperextension–external rotation (AB-HEER) test is overall the most accurate test to detect ILFL lesions. Injuries of the ILFL could be iatrogenic or a consequence of traumatic hip instability, and can be accurately studied with magnetic resonance imaging. Different arthroscopic and open techniques have been described in order to preserve the ILFL during surgery and, in case of lesions, several procedures with good to excellent results have been reported in the existing literature.

The current systematic review, focusing only on the ILFL of the hip, summarizes the existing knowledge on anatomy, imaging and function and contributes to the further understanding of the ILFL, confirming its key role in anterior hip stability. Future studies will have to develop clinical tests to evaluate the functionality and stability of the ILFL.

Cite this article: EFORT Open Rev 2021;6:545-555. DOI: 10.1302/2058-5241.6.200112

Hip Instability in Ballet Dancers: A Narrative Review

BACKGROUND

Dancers possess a large degree of hip range of motion that results from a combination of innate and acquired osseous morphology and permissive soft tissues. Generalized hypermobility in dancers may predispose them to a spectrum of hip instability. The objective of this narrative review is to discuss the anatomical characteristics, pathogenesis, risk factors, clinical signs and symptoms, management, and outcomes of hip instability treatments in dancers.

METHODS

A retrospective search was performed beginning November 1, 2017, for English language articles regarding hip stability in the dancer. Key words used included but were not limited to: dance(r), ballet, hip, hypermobility, range of motion, instability, microinstability, and laxity. PubMed, Scopus, and MEDLINE databases were used.

RESULTS

Forty-three studies were analyzed. Groin pain was found to be the most common presenting symptom of hip instability. A variety of impingement and instability signs may be elicited during physical examination. Hypermobility is frequently observed and is thought to be a necessity for participation in elite levels of ballet. Radiographs and advanced planar imaging (magnetic resonance imaging and computed tomography) should be scrutinized to evaluate for dysplasia, cam, pincer, subspine, and rotational morphologies. Dysplasia (low volume acetabulum), cam morphology, femoral retroversion, and coxa valga are common findings in the ballet dancers' hip. Labral injuries and ligamentum teres tears are common and may potentiate instability in the hip. Management options include education, oral non-opioid medications, activity modification, exercise prescription, and surgery. Reported outcomes of these treatments in ballet are limited.

CONCLUSION

Hip hypermobility is prevalent in the ballet population and is a clear advantage. However, it may increase the risk of instability. It is important to identify the multifactorial osseous and soft tissue etiology of hip or groin pain in dancers. Practitioners should have a high level of suspicion for hip instability in the dancer presenting with hip pain and treat accordingly. There is a significant need for increased quantity and quality of investigation into the outcomes of treatment for hip instability in the dancer.

Anatomic evaluation of the insertional footprints of the iliofemoral and ischiofemoral ligaments: a cadaveric study

Background

An understanding of the insertional footprints of the capsular ligaments of the hip is important for preserving hip function and stability given the increasing number of minimally invasive hip surgeries being performed under a limited surgical view. However, it is difficult to detect these ligaments intraoperatively and many surgeons may not fully appreciate their complex anatomy. The aims of this study were to quantify the proximal and distal footprints of the iliofemoral ligament (ILFL) and ischiofemoral ligament (ISFL) and to estimate the location of the corresponding osseous landmarks on the proximal femur, which can be detected easily during surgery.

Methods

Twelve hip joints from Japanese fresh frozen cadavers were used. All muscle, fascia, nerve tissue, and vessels were removed to expose the intact capsular ligaments of the hip. The length and width of the proximal and distal footprints of the ILFL and ISFL were measured and their relationship to osseous structures was evaluated, including the intertrochanteric line, femoral neck, and lesser trochanter.

Results

The mean length of the distal medial arm of the ILFL footprint was 17.9 mm and the mean width was 9.0 mm. The mean length of the distal lateral arm of the ILFL footprint was 23.0 mm and the mean width was 9.7 mm. For the footprint of the medial arm, the insertion was in the distal third of the intertrochanteric line and that of the lateral arm was in the proximal 42% of this line. The mean distance from the lesser trochanter to the footprint of the medial arm was 24.6 mm. The mean length of the distal ISFL footprint was 11.3 mm and the mean width was 6.9 mm. The footprint of the distal ISFL was located forward of the femoral neck axis in all specimens.

Conclusions

Understanding the size and location of each capsular ligament footprint in relation to an osseous landmark may help surgeons to manage the hip capsule intraoperatively even under a narrow surgical view. The findings of this study underscore the importance of recognizing that the distal ISFL footprint is located relatively forward and very close to the distal lateral arm footprint.

A Biomechanical Comparison of 2 Hip Capsular Reconstruction Techniques: Iliotibial Band Autograft Versus Achilles Tendon Allograft

BACKGROUND

Several techniques for hip capsular reconstruction have been described to address gross instability or microinstability due to capsular deficiency. However, objective biomechanical data to support their use are lacking.

PURPOSE

To compare the kinematic effect of 2 capsular reconstruction techniques (iliotibial band [ITB] graft and Achilles tendon graft). Kinematic effect encompassed rotational range of motion (ROM) as well as joint translation in the coronal, sagittal, and axial planes.

STUDY DESIGN

Controlled laboratory study.

METHODS

8 paired, fresh-frozen hemi-pelvises (16 hips) were tested on a custom-designed joint motion simulator in the intact state and after capsulectomy. Pairs were randomly allocated to either ITB or Achilles reconstruction and retested. Testing was performed at 0°, 45°, and 90° of flexion. Internal-external rotation (IR-ER) torques and abduction-adduction torques of 3 N·m were applied to the femur via a load cell at each position, and rotational ROM and joint translation in the coronal, sagittal, and axial planes were recorded.

RESULTS

At 45° and 90°, there was a significant effect of the condition of the hip on the total IR-ER (P = .004, effect size [ES] = 0.305; and P < .001, ES = 0.497; respectively). At 45°, mean ± SD total rotation was significantly greater for the capsulectomy (59.7°± 15.9°) state compared with intact (53.3°± 13.2°; P = .007). At 90°, reconstruction significantly decreased total rotation to 49.0°± 18.9° compared with a mean total rotation of 52.8°± 18.7° after capsulectomy (P = .02). No difference was seen in the total abduction-adduction of the hip between conditions. Comparisons of the 2 different reconstruction techniques showed no significant differences in total IR-ER or abduction-adduction ROM or joint translation in the coronal, sagittal, or axial planes. For translation, at both 0° and 45° there was a statistically significant effect of the condition on the medial-lateral translation (P = .033; ES = 0.204). Reconstruction, independent of technique, was successful in significantly decreasing (P = .030; P = .014) the mean medial-lateral translation at 0° and 45° of hip flexion from 5.2 ± 3.8 mm and 5.6 ± 4.0 mm to 2.8 ± 1.9 mm and 3.9 ± 3.2 mm, respectively.

CONCLUSION

The integrity of the native hip capsule played a significant role in rotational stability, where capsulectomy significantly increased rotational ROM. Both ITB and Achilles reconstruction techniques restored normal rotational ROM of the hip at 90° of flexion as well as coronal plane stability at 0° and 45° of hip flexion. No differences were seen between ITB and Achilles reconstruction techniques.

CLINICAL RELEVANCE

Both capsular reconstruction techniques provide comparable joint kinematics, restoring rotation and translation to normal values with the exception of rotational ROM at 45°, which remained significantly greater than the intact state. The most significant results were the rotational stability at 90° of hip flexion and coronal plane stability at 0° and 45° of hip flexion, which were significantly improved compared with the capsulectomy state.

Hip capsular strain varies between ligaments dependent on both hip position- and applied rotational force

PURPOSE

To noninvasively characterize the ligament strain in the hip capsule using a novel CT-based imaging technique.

METHODS

The superior iliofemoral ligament (SIFL), inferior iliofemoral ligament (IIFL), ischiofemoral ligament (IFL) and pubofemoral ligament (PFL) were identified and beaded in seven cadavers. Specimens were mounted on a joint motion simulator within an O-arm CT scanner in - 15°, 0°, 30°, 60°, and 90° of flexion. 3 Nm of internal rotation (IR) and external rotation (ER) were applied and CT scans obtained. Strains were calculated by comparing bead separation in loaded and unloaded conditions. Repeated-measures ANOVA was used to evaluate differences in strain within ligaments between hip positions.

RESULTS

For the SIFL, strain significantly decreased in IR at 30° (p = 0.045) and 60° (p = 0.043) versus 0°. For ER, there were no significant position-specific changes in strain (n.s.). For the IIFL, strain decreased in IR and increased in ER with no significant position-specific differences. For the IFL, strain increased with IR and decreased with ER with no significant position-specific differences. Finally, in the PFL there was a significant flexion angle-by-load interaction (p < 0.001; ES = 0.566), with peak strains noted at 60˚, however pair-wise comparisons failed to identify significant differences between positions (n.s.). Strain decreased in ER, with no significant position-specific differences.

CONCLUSION

The SIFL and IIFL limit hip external rotation with greater effect in higher flexion angles, while the IFL and PFL limit hip internal rotation. Following hip arthroscopy, consideration should be given to restricting external rotation as traditional capsulotomies cause injury to the SIFL and IIFL.

The effect of high, medium and low mobilization forces applied during a hip long-axis distraction mobilization on the strain on the inferior ilio-femoral ligament and psoas muscle: A cadaveric study

BACKGROUND

Several studies have suggested that the changes in elasticity of the joint capsule and surrounding muscles during a hip long-axis distraction mobilization (LADM) could explain the pain-relieving and mobility-improving effects of the technique.

OBJECTIVE

To compare the strain on the inferior ilio-femoral ligament and psoas muscle when applying three different magnitudes of force during LADM.

DESIGN

Repeated measures controlled laboratory cadaveric study.

METHODS

Eleven hip joints were mobilized from six fresh-frozen cadavers (mean age, 73.4 ± 5.7 years). Three magnitudes of force (low, medium and high) were applied during a hip LADM in open-packed position according to grades of joint mobilization. Strain on the inferior ilio-femoral ligament and psoas muscle were measured with strain gauges. The magnitude of the force applied during LADM was recorded.

RESULTS

Strain on the inferior ilio-femoral ligament during a high-force LADM was significantly higher than strain on the inferior ilio-femoral ligament during low (p < 0.001) and medium-force LADM (p < 0.001). The strain on the inferior ilio-femoral ligament during a medium-force LADM was significantly higher than during a low-force LADM (p = 0.004). No changes in strain on psoas muscle were observed. The magnitude of force applied during LADM showed a significant progressive increase from low to high-force LADM.

CONCLUSION

The different magnitudes of forces applied during LADM produce different strains on the inferior ilio-femoral ligament but not on the psoas muscle. The strain on the inferior ilio-femoral ligament during LADM depends on the magnitude of the mobilization force.

An Anatomic Study of the Damage to Capsular Hip Stabilizers During Subspine Decompression Using a Transverse Interportal Capsulotomy in Hip Arthroscopy

PURPOSE

To quantify the damage to the soft tissue stabilizers of the hip after a transverse interportal capsulotomy and subspine trimming in hip arthroscopy.

METHODS

Eight human cadaveric hemipelvises underwent hip arthroscopy through a transverse interportal capsulotomy. Arthroscopic subspine trimming performed on all specimens was classified according to an anatomic index. The width of the proximal capsule was measured before and after subspine trimming. The extent of damage to the iliofemoral ligament (IFL) after dissection was recorded. Potential damage to pericapsular structures was assessed by measuring the distance between the capsulotomy and rectus femoris and iliocapsularis muscle with an electronic caliper.

RESULTS

In all specimens, ≥50% of the width of the IFL was damaged. The subspine trimming was successfully performed in 7 of 8 specimens (87.5%) according to the proposed index. The sizes of the trimmed bone area measured in the anteroposterior and proximal-distal axis were 21.2 ± 7.5 and 13.1 ± 9 mm, respectively (mean ± standard deviation). The width of the proximal capsule at the anterior and posterior corner of the capsulotomy was 19.8 ± 5.2 and 11.8 ± 1.7 mm, respectively. After subspine trimming, the mean width of the anterior and posterior proximal capsular attachments was 6.4 ± 1.4 and 7.0 ± 1.6 mm, respectively. On average, 13.4 mm of anterior capsule was damaged after anterior inferior iliac spine trimming, versus 4.7 mm of the posterior capsule. The distances from the capsulotomy to the rectus femoris direct and reflected head were 6.8 ± 4.9 and 6.3 ± 7.7 mm, respectively, and to the iliocapsularis muscle, 11.5 ± 7.8 mm.

CONCLUSION

High rates of damage to the IFL were observed with the interportal capsulotomy. Increased tissue damage at the anterior capsule was observed after subspine trimming. The width of the proximal capsular attachment was ≥5 mm in all specimens.

CLINICAL RELEVANCE

Surgeons should be aware of the potential damage to the native capsule and pericapsular structures when using a transverse interportal capsulotomy for the arthroscopic subspine decompression.

LEVEL OF EVIDENCE

IV: cadaveric study, case series.

Editorial Commentary: #Capsule-ophilesRejoice! The Evidence in Support of Diligent Capsular Management During Hip Arthroscopy Can No Longer Be Ignored

From its infancy until now, the enthusiasm and growth of the field of hip arthroscopy have been exciting to watch. Perhaps, it could be argued that there has not been a more hotly debated topic in recent years than what to do with the hip capsule. Once merely an afterthought in the context of hip arthroscopy, the oft overlooked and underappreciated intricacies of hip capsular anatomy and its role in hip stability have now taken center stage. As surgical indications continue to expand, our surgical techniques have rapidly evolved. Despite the rapid growth and advent of industry, the leaders in this field have remained steadfast in their relentless quest to improve their scientific knowledge and understanding of the native hip joint. If we have learned nothing else from watching the capsular debate evolve, it is that without an advanced understanding of the critical and complex marriage of anatomy and function that exists in a healthy hip joint, we cannot begin to master the surgical treatment of its pathologic states.

Preoperative radiographic features of trochanteric fractures irreducible by closed reduction

INTRODUCTION

The aim of this study was to clarify the relationship between the preoperative radiographic classification of trochanteric fractures and the success/failure of closed reduction. Identification of irreducible fractures would be important to proceed promptly to direct reduction.

PATIENTS AND METHODS

Our retrospective analysis included 141 trochanteric fractures, in 122 women and 17 men, with a mean age of 85.7 years (range, 45-101 years). Evans' classification of trochanteric fractures, as modified by Jensen, and the lateral view classification were used, based on preoperative plain radiographs and computed tomography images. Features predictive of irreducible fractures were identified.

RESULTS

Among the 141 fractures, 16 (11.3%) were irreducible by closed reduction. The position of the proximal fragment, relative to the shaft on lateral view, and the fracture pattern of the lesser and greater trochanters were predictive of the feasibility of obtaining a successful closed reduction. These criteria identified success/failure of closed reduction in 99.3% of cases.

CONCLUSION

Our findings should be useful for identifying patients in whom closed reduction would be suitable and for avoiding ineffectual manipulation in unsuitable patients.

Gait- and Posture-Related Factors Associated With Changes in Hip Pain and Physical Function in Patients With Secondary Hip Osteoarthritis: A Prospective Cohort Study

OBJECTIVE

To identify gait- and posture-related factors associated with changes in hip pain and physical function in patients with hip osteoarthritis (OA).

DESIGN

Prospective cohort study.

SETTING

Clinical biomechanics laboratory of a university.

PARTICIPANTS

Consecutive sampling of female patients with mild-to-moderate secondary hip OA (N=30).

MAIN OUTCOME MEASURES

Hip pain (visual analog scale) and physical function (physical component summary of the Medical Outcomes Study 36-Item Short-Form Health Survey) were measured at baseline and 12 months later. With changes in hip pain and physical function as dependent variables, linear regression analyses were performed with gait- and posture-related factors as independent variables with and without adjustment for age, joint space width, and hip pain or physical function at baseline. Posture-related factors included angles of thoracic kyphosis, lumbar lordosis, sacral inclination, spinal inclination, and spinal mobility. Gait-related factors were walking speed, steps per day, joint angles, external hip joint moment impulses, and daily cumulative hip moments.

RESULTS

Multiple linear regression analyses showed that limited hip extension (adjusted standardized B coefficient [95% confidence interval]: -0.52 [-0.88 to -0.17]) and limited external rotation angles (-0.51 [-0.85 to -0.18]) during walking were associated with the worsening of hip pain. An increased thoracic kyphosis (-0.54 [-0.99 to -0.09]), less sacral anterior tilt (0.40 [0.01-0.79]), reduced thoracic spine mobility (0.59 [0.23-0.94]), less steps per day (0.53 [0.13-0.92]), and a slower walking speed (0.45 [0.04-0.86]) were associated with deterioration in physical function.

CONCLUSIONS

Gait- and posture-related factors should be considered when assessing risk and designing preventive interventions for the clinical progression of secondary hip OA.

Complete Capsular Repair Restores Native Kinematics After Interportal and T-Capsulotomy

BACKGROUND

Although the use of hip arthroscopy continues to increase, capsular management remains a controversial topic.

PURPOSE

To investigate the biomechanical effect of capsulotomy and capsular repair techniques on hip joint kinematics in varying combinations of sagittal and coronal joint positions.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight fresh-frozen hemi-pelvises (78.3 ± 6.0 years of age; 4 left, 6 male) were dissected of all overlying soft tissue, with the exception of the hip joint capsule. The femur was potted and attached to a load cell, while the pelvis was secured to a custom-designed fixture allowing static alteration of the flexion-extension arc. Optotrak markers were rigidly attached to the femur and pelvis to track motion of the femoral head with respect to the acetabulum. After specimen preparation, 7 conditions were tested: (1) intact, (2) after portal placement (anterolateral and midanterior), (3) interportal capsulotomy (IPC) (35 mm in length), (4) IPC repair, (5) T-capsulotomy (IPC +15-mm longitudinal incision), (6) partial T-repair (repair of longitudinal incision with IPC left open), (7) full T-repair. All conditions were tested in 15° of extension (-15°), 0°, 30°, 60°, and 90° of flexion. Additionally, all flexion angles were tested in neutral, as well as in specimen-specific maximum abduction and adduction, resulting in 15 testing positions. Internal rotation (IR) and external rotation (ER) moments of 3 N·m were manually applied to the femur via the load cell at each position. Rotational range of motion and joint kinematics were recorded.

RESULTS

In the neutral coronal plane, T-capsulotomy significantly increased IR/ER rotational range of motion compared with intact state at -15° (55.96°± 6.11° vs 44.92°± 7.35°, P < .001), while IPC significantly increased rotation compared with the portal state at 0° (60.09°± 6.82° vs 51.68°± 10.35°, P = .004). No statistically significant increases were found in mediolateral joint translation after IPC or T-capsulotomy. Similarly, no statistically significant increases were noted in anteroposterior translation after IPC or T-capsulotomy. Complete capsular repair restored near native joint kinematics, with no significant differences in rotation or translation between any complete capsular repair groups and the intact state, regardless of joint position.

CONCLUSION

Universally, across all conditions, complete capsular repair after interportal or T-capsulotomy restored rotational range of motion and joint translation to values observed in the native joint.

CLINICAL RELEVANCE

Where feasible, complete capsular closure should be performed, especially after T-capsulotomy. However, further clinical evaluation is required to determine whether adverse kinematic parameters of an unrepaired capsule are associated with reduced patient-reported outcomes.

Soft tissue restrictors of femoral elevation in direct anterior approach-an anatomic study

Background

With the patient in a constant supine position, elevation of the femur in THA (DAA) provides a more intuitive and conducive location of the acetabulum for the correct placement of the acetabular prosthesis, but elevation of the femur for broaching becomes more challenging. The purpose of this study is to analyze the restriction of the ischiofemoral ligament and short external rotation muscles, and its effect on the elevation of the proximal femur in the DAA.

Methods

The study subjects comprised 5 freshly frozen cadavers with 10 normal hips. All of the anatomic dissections of all of the hips were performed through the DAA. The ischiofemoral ligament, piriformis, conjoint tendon, and external obturator were successively resected. All of the proximal femurs of the specimens were levered by a point tip curved retractor that was connected with a dynamometer. Through preliminary measurements, an applied force of 80 N was adopted and maintained on the curved retractor. The experiment was repeated to measure the displacement of the proximal femur being raised after the posterior structures of the hip joint had been resected in a stepwise fashion. The displacement of the retractor was recorded, and the data were then analyzed.

Results

The distance significantly increased after the ischiofemoral ligament was severed (P < 0.001). A prominent increase was demonstrated after the conjoint tendons were severed (P < 0.001). The distance insignificantly increased after the piriformis was severed (P > 0.05). After the obturator externus was cut off, the distance increased by an insignificant amount (P > 0.05).

Conclusion

In DAA, the ischiofemoral ligament contributed stability when the femur was being raised. The main contribution of restriction was provided by the conjoint tendon. The tendons of the obturator externus muscle and piriformis muscle did not provide any significant restriction when the femur was being raised.

Gait Alterations in Femoroacetabular Impingement Syndrome Differ by Sex

Background Femoroacetabular impingement (FAI) syndrome may affect gait kinematics differently between males and females. Objectives To investigate whether individuals with FAI syndrome have different hip and pelvic motion during gait, at their preferred speed and a prescribed speed, compared to individuals of the same sex without pain. Methods Twenty-one participants (11 males and 10 females) with FAI syndrome and 41 participants (19 males and 22 females) without hip pain were included in this case-control laboratory study. There were no differences between the 2 groups in age, body mass index, and activity score. Kinematic data for all participants were collected while walking at a preferred speed and at 1.25 m/s. For sex and walking speed, linear regression analyses were used to examine the effect of group and the interaction of group by limb. Results At both speeds, males with FAI syndrome walked with more than 6° less peak hip extension (P≤.018), 5° greater anterior pelvic tilt (P≤.020), and 5° less posterior pelvic tilt (P≤.018) compared to males without hip pain. Females with FAI syndrome walked with 2° less hip extension (P≤.012) and at least 3° more hip adduction (P<.001) in the more painful hip than in the less painful hip at both speeds. Conclusion Males and females with FAI syndrome have different gait alterations when compared to a same-sex comparison group. In males, differences were between groups. In females with FAI syndrome, differences were between the more painful and the less painful limb. J Orthop Sports Phys Ther 2018;48(8):649-658. Epub 22 May 2018. doi:10.2519/jospt.2018.7913.

Contribution of the Ligamentum Teres to Hip Stability in the Presence of an Intact Capsule: A Cadaveric Study

PURPOSE

To determine the contribution of the ligamentum teres (LT) to hip stability in the presence of an intact capsule with special attention to the change in range of motion and femoral head translation.

METHODS

Seven fresh-frozen cadaveric pelvises were used. Following visual inspection of the LT at different hip positions, internal rotation angles were measured at 10° of extension and at 0° of flexion, while external rotation was measured at 60°, 90°, and 110° of flexion with different hip abduction angles using electromagnetic motion tracking sensor. Femoral head translations were measured simultaneously. The tests were repeated after resection of the LT. The capsule was left intact for all test conditions. The results were compared between intact and LT resected conditions when torque of 2 and 4 Nm was applied.

RESULTS

Compared with the intact hip, the LT resected hip showed no significant difference when 2 Nm torque was applied in all scenarios. With 4 Nm torque application, significant increase in external rotation was found at 60° and at 90° of flexion (1.7° ± 0.8° and 2.1° ± 1.0°, respectively). Significant difference was also noted at 60°, 90°, and 110° of flexion when the hip was in the adducted position while at 90° in the abducted hip. However, LT resection did not show significant change in internal rotation. There was no significant difference in the translation distance of the femoral head in the intact hip compared with the LT resected hip (0.77-1.11 mm vs 0.79-1.29 mm).

CONCLUSIONS

Our results indicate that within the physiologic range of motion, LT can minimally limit external rotation when the hip is in the flexed position but does not contribute to translation stability.

CLINICAL RELEVANCE

In the hip with intact capsule, LT deficiency can result in a slight increase in range of motion, but its contribution to stability is questionable.

Effect of wrist and finger flexion in relation to strain on the tendon origin of the extensor carpi radialis brevis: A cadaveric study simulating stretching exercises

BACKGROUND

Stretching exercises based on wrist flexion-ulnar deviation with elbow extension, forearm pronation, and additional index or middle finger flexion have been used to stretch the wrist extensors for lateral epicondylitis. The purpose of this study was to quantify the strain on the tendon origin of the extensor carpi radialis brevis in cadaver specimens during these stretching exercises.

METHODS

We used 8 fresh frozen/thawed cadaveric upper extremities. The strain on the extensor carpi radialis brevis tendon origin was measured by the addition of 4 types of traction (no traction, wrist flexion-ulnar deviation, and index or middle finger flexion in combination with wrist flexion-ulnar deviation) in 7 sequential elbow flexion angles during forearm pronation. Two types of varus stress load to the elbow (none, gravity on the forearm) were also applied.

FINDINGS

A significant increase in strain was obtained by wrist traction with 0°, 15° and 30° of elbow flexion (P<0.05). The strain was also significantly increased by adding finger traction (P<0.05) and varus stress load (P<0.05). A maximum strain value of 5.30 (SD 1.73) % was obtained when traction on the middle finger in combination with traction of the wrist was added at 15° elbow flexion with varus stress load.

INTERPRETATION

The present study provides data about the amount of strain on the extensor carpi radialis brevis tendon during stretching exercises of the wrist and finger extensors. The results of this study could be applied to stretching exercises for patients with lateral epicondylitis.

Contribution of the Pubofemoral Ligament to Hip Stability: A Biomechanical Study

PURPOSE

To determine the isolated function of the pubofemoral ligament of the hip capsule and its contribution to hip stability in external/internal rotational motion during flexion greater than 30° and abduction.

METHODS

Thirteen hips from 7 fresh-frozen pelvis-to-toe cadavers were skeletonized from the lumbar spine to the distal femur with the capsular ligaments intact. Computed tomographic imaging was performed to ensure no occult pathological state existed, and assess bony anatomy. Specimens were placed on a surgical table in supine position with lower extremities resting on a custom-designed polyvinylchloride frame. Hip internal and external rotation was measured with the hip placed into a combination of the following motions: 30°, 60°, 110° hip flexion and 0°, 20°, 40° abduction. Testing positions were randomized. The pubofemoral ligament was released and measurements were repeated, followed by releasing the ligamentum teres.

RESULTS

Analysis of the 2,106 measurements recorded demonstrates the pubofemoral ligament as a main controller of hip internal rotation during hip flexion beyond 30° and abduction. Hip internal rotation was increased up to 438.9% (P < .001) when the pubofemoral ligament was released and 412.9% (P < .001) when both the pubofemoral and teres ligament were released, compared with the native state.

CONCLUSIONS

The hypothesis of the pubofemoral ligament as one of the contributing factors of anterior inferior hip stability by controlling external rotation of the hip in flexion beyond 30° and abduction was disproved. The pubofemoral ligament maintains a key function in limiting internal rotation in the position of increasing hip flexion beyond 30° and abduction. This cadaveric study concludes previous attempts at understanding the anatomical and biomechanical function of the capsular ligaments and their role in hip stability.

CLINICAL RELEVANCE

The present study contributes to the understanding of hip stability and biomechanical function of the pubofemoral ligament.

Anterior Inferior Iliac Spine (AIIS) and Subspine Hip Impingement

BACKGROUND

Abnormal morphology of the anterior inferior iliac spine (AIIS) and the subspine region of the acetabular rim are increasingly being recognised as a source of symptomatic extra-articular hip impingement. This review article aims to highlight important differences in the pathogenesis, clinical presentation and management of extra-articular hip impingement from both the AIIS and subspine bony regions, and the outcome following surgical intervention.

METHODS

A literature review was undertaken to examine the supporting evidence for AIIS and subspine hip impingement. A narrative account of the Author's professional experience in this area, including operative technique for arthroscopic correction, is also presented.

RESULTS

Abnormal morphology of the AIIS and subspine region has been classified using cadaveric, radiological and arthroscopic means; the clinical presentation and operative treatment has been documented in several case series studies. Dual pathology is often present - recognition and treatment of both intra- and extra-articular components are necessary for good postoperative outcome.

CONCLUSIONS

AIIS and sub-spine hip impingement should be considered as distinct pathological entities, which may also co-exist. Symptom relief can be expected following arthroscopic deformity correction with the treatment of concomitant intra-articular pathology. Failure to recognise and treat the extra-articular component may affect postoperative outcome.

LEVEL OF EVIDENCE

V.

Passive hip movement measurements related to dynamic motion during gait in hip osteoarthritis

Reduced sagittal plane range of motion (ROM) has been reported in individuals with hip osteoarthritis (OA) both during walking and passive testing. The purpose of this study was to determine if a relationship exists between hip extension ROM recorded during gait and passive hip extension ROM in individuals with moderate and severe hip OA, in comparison to an asymptomatic group. Sagittal plane hip ROM was calculated using skin surface marker trajectories captured during treadmill walking at self-selected speed. Passive hip ROM was measured using standardized position and recording procedures with a goniometer. Sagittal plane extension, flexion, and overall ROM were measured dynamically and passively. A two-way mixed model analysis of variance determined significant differences between groups and between passive and dynamic ROM (α = 0.05). Pearson correlations determined relationships between passive and dynamic ROM. Significant group by ROM interactions were found for flexion and extension ROM (p < 0.05). For extension, the severe OA group had less dynamic and passive ROM compared to the other groups and greater passive than dynamic ROM (p < 0.05). For flexion, significant differences in passive ROM existed between all three groups (p < 0.05) whereas no differences were found for dynamic flexion (p < 0.05). Significant correlations between dynamic and passive hip extension were found in the moderate (r = 0.596) and severe OA (r = 0.586) groups, and no correlation was found in the asymptomatic group (r = 0.139). Passive ROM explains variance in dynamic ROM measurements obtained during gait in individuals with moderate and severe hip OA which have implications for the design of treatment strategies targeting walking pathomechanics. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1790-1797, 2016.