A quantitative assessment of the insertional footprints of the hip joint capsular ligaments and their spanning fibers for reconstruction

Capsular attachment on the anterosuperior femoral head-neck junction: A hypothesis about femoroacetabular impingement

Femoroacetabular impingement (FAI), characterized by a pathological contact between the proximal femur and acetabulum, is a common precursor of hip osteoarthritis. Cam morphology is a bony prominence that causes FAI and frequently forms on the anterosuperior femoral head-neck junction. Despite anatomical consensus regarding the femoral head-neck junction as a boundary area covered by the articular cartilage and joint capsule, it remains unclear whether the joint capsule is continuous with the anterosuperior articular cartilage. For the anatomical consideration of cam morphology formation, this study aimed to investigate the histological characteristics of the capsular attachment on the anterosuperior femoral head-neck junction, particularly focusing on the presence or absence of continuity of the joint capsule to the articular cartilage. A total of 21 anterosuperior regions (seven hips each for the 12:00, 1:30, and 3:00 positions) from seven hips (three males and four females; mean age at death, 68.7 years) were histologically analyzed in this study for quantitative evaluation of the capsular thickness using histological sections stained with Masson's trichrome, as well as qualitative evaluation of the capsular attachment. The present study showed that the joint capsule, which folded proximally to the femoral head-neck junction from the recess, exhibited a blend of the fibrous and synovial regions. Notably, it not only continued with the superficial layer of the articular cartilage, but also attached to the articular cartilage via the fibrocartilage. This continuous region was relatively fibrous with dense connective tissue running in the longitudinal direction. The capsular thickness at the recess point (mean, 1.7 ± 0.9 mm) and those at the distal end of the articular cartilage (0.35 ± 0.16 mm) were significantly greater than the control value for the most superficial layer thickness of the articular cartilage (0.019 ± 0.003 mm) (Dunnett's T3, both p-value <0.001). Based on the fibrous continuity between the joint capsule and articular cartilage and its thickness, this study suggests the anatomical possibility that some mechanical stress can be transmitted from the joint capsule to the articular cartilage at the frequent sites of cam morphology.

Instantaneous Generation of Subject-Specific Finite Element Models of the Hip Capsule

Subject-specific hip capsule models could offer insights into impingement and dislocation risk when coupled with computer-aided surgery, but model calibration is time-consuming using traditional techniques. This study developed a framework for instantaneously generating subject-specific finite element (FE) capsule representations from regression models trained with a probabilistic approach. A validated FE model of the implanted hip capsule was evaluated probabilistically to generate a training dataset relating capsule geometry and material properties to hip laxity. Multivariate regression models were trained using 90% of trials to predict capsule properties based on hip laxity and attachment site information. The regression models were validated using the remaining 10% of the training set by comparing differences in hip laxity between the original trials and the regression-derived capsules. Root mean square errors (RMSEs) in laxity predictions ranged from 1.8° to 2.3°, depending on the type of laxity used in the training set. The RMSE, when predicting the laxity measured from five cadaveric specimens with total hip arthroplasty, was 4.5°. Model generation time was reduced from days to milliseconds. The results demonstrated the potential of regression-based training to instantaneously generate subject-specific FE models and have implications for integrating subject-specific capsule models into surgical planning software.

Comparable Torque to Failure Using the Simple Stich Versus the Figure-of-Eight Configuration for Hip Capsular Closure Following an Interportal Capsulotomy: A Cadaveric Study

PURPOSE

To measure and compare the torque to failure and stiffness of the capsular repair construct consisting of four-suture simple stitches to a two-figure of eight stitches repair construct in external rotation following an interportal capsulotomy.

METHODS

Six pairs of fresh-frozen cadaveric hemipelves were divided into two capsular repair groups. All hips underwent a 40-mm interportal capsulotomy from the 12 o'clock position to the 3 o'clock position. Capsular closure was performed using either the two stitches in a figure of eight or with four simple stitches. Afterward, each hemipelvis was securely fixed to the frame of a mechanical testing system with the hip in 10° of extension and externally rotated to failure. Significance was set at P < .05.

RESULTS

The average failure torque was 86.2 ± 18.9 N·m and 81.5 ± 8.9 N·m (P = .57) for the two stitches in a figure of eight and the four simple stitches, respectively. Failure stiffness was also not statistically different between groups and both capsular closure techniques failed at similar degrees of rotation (P = .65).

CONCLUSION

Hip capsular repair using either the four simple stitch or two-figure of eight configurations following interportal capsulotomy demonstrated comparable failure torques and similar stiffness in a cadaveric model.

CLINICAL RELEVANCE

Adequate and comprehensive capsular management in hip arthroscopy is critical. Capsular repair following capsulotomy in femoroacetabular impingement surgery has been associated with higher patient-reported outcomes when compared to capsulotomy without repair. Therefore, determining which capsular closure construct provides the higher failure torque is important.

Biomechanical Evaluation of 4 Suture Techniques for Hip Capsular Closure

Background:

The most reliable suture technique for capsular closure after a capsulotomy remains unknown.

Purpose:

To determine which suture technique best restores native stability after a 5-cm interportal capsulotomy.

Study Design:

Controlled laboratory study.

Methods:

Ten human cadaveric hip specimens were tested using a 6-degrees-of-freedom robotic arm in 7 states: intact, capsular laxity, 5-cm capsulotomy, standard suture, shoelace, double shoelace, and Quebec City slider (QCS). Rotational range of motion (ROM) was measured across 9 tests: flexion, extension, abduction, abduction at 45° of flexion, adduction, external rotation, internal rotation, anterior impingement, and log roll. Distraction (ie, femoral head translation [FHT]) was measured across a range of flexion and abduction angles.

Results:

When compared with the native state, the 5-cm capsulotomy state showed the largest laxity increases on all tests, specifically in external rotation ROM (+13.4°), extension ROM (+11.5°), and distraction FHT (+4.5 mm) (P < .001 for all). The standard suture technique was not significantly different from the 5-cm capsulotomy on any test and demonstrated significantly more flexion ROM than the double shoelace suture (+1.41°; P = .049) and more extension ROM (+5.51°; P = .014) and external rotation ROM (+6.03°; P = .021) than the QCS. The standard suture also resulted in significantly higher distraction FHT as compared with the shoelace suture (+1.0 mm; P = .005), double shoelace suture (+1.4 mm; P < .001), and QCS (+1.1 mm; P = .003). The shoelace, double shoelace, and QCS techniques significantly reduced hip laxity when compared with the 5-cm capsulotomy state, specifically in external rotation ROM (respectively, –8.1°, –7.8°, and –10.2°), extension ROM (–6.3°, –7.3°, and –8.1°), and distraction FHT (–1.8, –2.2, and –1.9 mm) (P ≤ .003 for all). These 3 techniques restored native stability (no significant difference from intact) on some but not all tests, and no significant differences were observed among them on any test.

Conclusion:

Hip capsule closure with the standard suture technique did not prevent postoperative hip instability after a 5-cm capsulotomy, and 3 suture techniques were found to be preferable; however, none perfectly restored native stability at time zero.

Clinical Relevance:

The shoelace, double shoelace, and QCS suture techniques are recommended when closing the hip capsule.

Clinical anatomy of the musculoskeletal system in the hip region

Although the hip joint is regarded as inherently stable, hip pain and injuries caused by traumatic/non-traumatic hip instability are relatively common in active individuals. A comprehensive understanding of hip anatomy may provide better insight into the relationships between hip stability and clinical problems. In this review, we present our recent findings on the hip morphological characteristics, especially focusing on the intramuscular tendon of the gluteus medius tendon and its insertion sites, hip capsular attachment on the anterosuperior region of the acetabular margin, and composition of the iliofemoral ligament. We further discussed the hip stabilization mechanism based on these findings. The characteristics of the gluteus medius tendon suggest that even a single muscle has multiple functional subunits within the muscle. In addition, the characteristics of the hip capsular attachment suggest that the width of the capsular attachment is wider than previously reported, and its wide area shows adaptive morphology to mechanical stress, such as bony impression and distribution of the fibrocartilage. The composition of the iliofemoral ligament and its relation to periarticular structures suggest that some ligaments should be defined based on the pericapsular structures, such as the joint capsule, tendon, and aponeurosis, and also have the ability to dynamically coordinate joint stability. These anatomical perspectives provide a better understanding of the hip stabilization mechanism, and a biomechanical study or an in vivo imaging study, considering these perspectives, is expected in the future.

[Patterns and research progress on the concomitant ipsilateral fractures of intracapsular femoral neck and extracapsular trochanter]

OBJECTIVE

To summarize the patterns and research progress of the concomitant ipsilateral fractures of intracapsular femoral neck and extracapsular trochanter, and to provide a common language among orthopedic surgeons for scientific exchange.

METHODS

According to related literature and authors own experiences concerning the anatomic border between femoral neck and trochanter region, the intertrochanteric line (or intertrochanteric belt) and its capsularligament attachment footprint, fracture patterns, and treatment strategies were reviewed and analyzed.

RESULTS

With the rapid growing of geriatric hip fractures, an increased incidence was noted in recent years regarding the proximal femoral comminuted fractures that involving ipsilateral intracapsular neck and extracapsular trochanter regions simultaneously. But the concept of femoral neck combined with trochanter fractures was ambiguous. Based on the anatomic type of femoral neck fracture, the location of fracture center, and the ability to achieve direct inferior calcar or anteromedial cortex-to-cortex apposition and buttress, we classified these complex fractures into 3 sub-types: ① Segmental femoral neck fractures (two separate fracture centers at subcapital and trochanteric region respectively); ② Femoral neck fracture (trans-cervical) with extension to the supero-lateral trochanteric region (fracture center in femoral neck); ③ Trochanteric fracture with extension to the medio-inferior femoral neck region (fracture center in trochanter, comminuted basicervical fracture, or variant type of comminuted trochanter fracture). For treatment strategy, surgeons should consider the unique characteristics of femoral neck and trochanter, usually with combined fixation techniques, or arthroplasty supplemented with fixation.

CONCLUSION

Currently there is no consensus on diagnosis and terminology regarding the concomitant ipsilateral fractures of femoral neck and trochanter. Further studies are needed.

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.

Dynamic changes of the joint capsule in relation to the zona orbicularis: An anatomical study with possible implications for hip stability mechanism

The zona orbicularis, which comprises the inner circular fibers of the joint capsule, is vital for hip stability in distraction. Despite the proximity of the whole joint capsule to the zona orbicularis, their anatomical relationship remains unclear. The aim of this study is to investigate the characteristics of the inner side of the joint capsule comprehensively. Twelve hips from nine bodies donated to science were examined. Six and three of the donated bodies, respectively, were embalmed using 8% formalin and Thiel's method. The joint capsules in three formalin‐embalmed bodies were sturied by micro‐computed tomography. During formalin fixation of six hips from these three bodies, one side was maintained at hip extension and the other at flexion. The remaining three formalin‐embalmed bodies were examined histologically. Micro‐computed tomography images revealed that the inward protrusion of the joint capsule narrowed the articular cavity, and the ratio of its narrowest area to that of the femoral neck was less at hip extension than at hip flexion. The Thiel's method specimens showed that the inner surface of the joint capsule protruded inward toward the femoral neck during hip extension. This inward protrusion was not histologically independent of the joint capsule. The zona orbicularis was interpreted as the inward protrusion caused by dynamic change of the joint capsule, rather than the local collar. In other words, the joint capsule could change its morphology dynamically depending on the hip position.

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

Arthroscopic Triple Reconstruction in the Hip Joint: Restoration of Soft-Tissue Stabilizers in Revision Surgery for Gross Instability

Gross hip instability in an active adult with previous normal hip anatomy is usually due to disruption of the static stabilizers of the hip joint. Although such a disruption can result from a high-grade injury, it can be iatrogenic after previous hip arthroscopy. The patient may present with a painful limp and recurrent subluxation sensation in the affected hip joint. Revision hip arthroscopy in this scenario is generally complicated, and it is not uncommon for all the soft-tissue stabilizers to be compromised. The labrum, ligamentum teres (LT), and capsule of the hip joint are often so damaged that reparation is not an option. Reconstruction of the torn LT is an established method to add secondary stability while addressing the labral pathology in the hip joint with microinstability. Concomitant reconstruction of all the static restraints has yet to be described addressing triple instability. This Technical Note presents a stepwise approach, including tips and pearls, for arthroscopic triple reconstruction of the labrum, LT, and capsule. We believe this method is a safe and reproducible way to effectively treat gross hip instability in young patients.

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.

Portal enlargement in hip arthroscopy preserving the iliofemoral ligament: a novel access technique protecting soft tissue restraints

Capsulotomy in different modalities has been used to provide adequate exposure to access both the central and peripheral compartment in hip arthroscopy. Even though the hip joint has inherent bony stability, soft tissue restraints may be important in patients with ligaments hyperlaxity or in some cases with diminished bony stability. Biomechanical studies and clinical outcomes have shown the relevant role of the capsule in hip stability, mainly the role of the iliofemoral ligament. Although is not very common, iatrogenic post-arthroscopy subluxation and dislocation have been reported and many surgeons are concerned about the role aggressive capsulotomy or capsulectomy in this situation, thus capsule repair has become very popular. We present a novel technique to access the hip without cutting the iliofemoral ligament. With this technique we can obtain adequate arthroscopic access to the hip joint in order to treat adequately the central compartment pathologies reducing the risk of iatrogenic post-operative hip instability.

Surgical Outcomes in the Treatment of Concomitant Mild Acetabular Dysplasia and Femoroacetabular Impingement: A Systematic Review

PURPOSE

To analyze the current approaches and clinical outcomes in the surgical management of concomitant mild acetabular dysplasia and femoroacetabular impingement (FAI).

METHODS

Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) method, the PubMed and Medline databases were searched in March 2019 for studies that reported on surgical outcomes in hips with concomitant mid acetabular dysplasia and FAI. Studies published in English that focused on the surgical outcomes after hip arthroscopy, open surgery, or periacetabular osteotomy of concomitant acetabular dysplasia and FAI, in which the lateral center-edge angle of all subjects was between 15° and 25°, were included. Articles that included subjects with lateral center-edge angle <15°, with a minimum follow-up duration <1 year, had <5 subjects, or were not original articles were excluded.

RESULTS

The initial search yielded 748 studies, and 5 studies met the inclusion criteria. All these 5 studies focused on hip arthroscopic treatment for patients with concomitant mild acetabular dysplasia and FAI. Three studies had level III evidence, whereas 2 studies had level IV evidence. The mean patient age range across the studies was 29.8 to 49.6 years, and the female-to-male ratio was 1.14. Improved patient-reported outcomes (Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sport, modified Harris Hip Score, Short Form-12 Physical Component Summary, Western Ontario and McMaster Universities Osteoarthritis Index) at a minimum 2-year follow-up were obtained in 4 of the 5 studies. Two of these 4 studies had a comparative cohort of patients with FAI with normal acetabular coverage, and there was no significant difference in the postoperative outcomes and secondary procedure rate between patients with mild acetabular dysplasia and those with normal acetabular coverage.

CONCLUSIONS

This systematic review indicates that improved patient-reported outcomes can be obtained with hip arthroscopy in the treatment of concomitant mild acetabular dysplasia and FAI at a minimum 2-year follow-up.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and Level IV studies.

Hip Joint Capsular Anatomy, Mechanics, and Surgical Management

➤Hip joint capsular ligaments (iliofemoral, ischiofemoral, and pubofemoral) play a predominant role in functional mobility and joint stability. ➤The zona orbicularis resists joint distraction (during neutral positions), and its aperture mechanism stabilizes the hip from adverse edge-loading (during extreme hip flexion-extension). ➤To preserve joint function and stability, it is important to minimize capsulotomy size and avoid disrupting the zona orbicularis, preserve the femoral head size and neck length, and only repair when or as necessary without altering capsular tensions. ➤It is not fully understood what the role of capsular tightness is in patients who have cam femoroacetabular impingement and if partial capsular release could be beneficial and/or therapeutic. ➤During arthroplasty surgery, a femoral head implant that is nearly equivalent to the native head size with an optimal neck-length offset can optimize capsular tension and decrease dislocation risk where an intact posterior hip capsule plays a critical role in maintaining hip stability.

Anterior Capsule Reconstruction of the Native Hip: A Technique Guide

This is a technique guide for open anterior capsule reconstruction in unstable native hips due to Ehlers-Danlos syndrome. Ehlers-Danlos syndrome is a connective tissue disease that predisposes an individual to hypermobility of their soft tissues and recurrent subluxations and dislocations of their joints. This may lead to constant instability, guarding of the hip, and subsequent arthritic changes and poor quality of life. We demonstrate anterior capsule reconstruction of the hip using an Achilles tendon allograft performed through a direct anterior approach to the hip (Heuter's approach). This technique guide outlines in detail the surgical steps required to accomplish this reconstructive procedure. Furthermore, a narrated surgical video is provided that clearly depicts the anticipated result of the increased constrained provided to the hip from the anterior capsule reconstruction using an Achilles tendon allograft.

Tension-free closure with capsular lengthening in mini posterior total hip replacement

PURPOSE:

Choice of the best mini invasive surgical approach for total hip replacement remains a controversial topic. The posterior approach is traditionally associated with a higher dislocation rate and the obligation of postoperative restrictions. Soft tissue repair reduces the risk of dislocation yet, posterior closure it is often challenging because of capsular and external rotator contractures. In this article, an original procedure of capsular lengthening and tension-free closure is described and the results of a retrospective single surgeon series of minimally invasive posterior total hip replacement (THR) with capsular repair are presented.

METHODS:

A total of 925 mini posterior total hip replacements performed between 2009 and 2015 were retrospectively reviewed. 2 original types of capsulorrhaphy to decrease tension of the repaired tissues were employed. Absence of posterior envelope stretch during flexion and internal rotation was confirmed intraoperatively with a dynamic test. No postoperative restrictions were used.

RESULTS:

Capsular lengthening with 1 of the described techniques was required in over 50% of cases for a tension-free closure. 3 patients dislocated in the 867 reviewed procedures (0.35%), 1 requiring revision for instability (0.11%).

CONCLUSIONS:

This soft tissue repair technique after mini posterior approach THR is technically easy, provides a tension-free closure and a low dislocation rate.

Hip capsular thickness correlates with range of motion limitations in femoroacetabular impingement

PURPOSE

Femoroacetabular impingement (FAI) is a clinical entity of the hip causing derangements in range of motion, pain, gait, and function. Computer-assisted modeling and clinical studies suggest that patients with FAI have increased capsular thickness compared to those without.A retrospective chart review was performed to assess relationships between capsular thickness, hip range of motion, and demographic factors in patients with FAI.

METHODS

Local Research Ethics Board approval was obtained to extract electronic medical records for 188 patients at a single institution who had undergone hip arthroscopy. Procedures were performed from 2009 to 2017 by a single, fellowship-trained, board-certified sports medicine orthopaedic surgeon. Inclusion criteria were preoperative hip range of motion testing, positive clinical impingement testing, and magnetic resonance imaging (MRI) of the affected hip. Patient demographics, hip range of motion, and time to surgery were recorded. MRIs were reviewed by a board-certified musculoskeletal radiologist blinded to clinical data. Maximum thickness of the anterior hip capsule was measured in axial, axial oblique, and sagittal oblique sequences. Anterior capsular thickness was also measured at the level of the femoral head-neck junction in axial sequences (axial midline).

RESULTS

Axial midline capsular thickness was negatively correlated with hip flexion (r = - 0.196, p = 0.0042) and internal rotation (r = - 0.143, p = 0.0278). Significant differences were seen between genders in axial midline thickness (5.3 ± 1.4 mm males/4.8 ± 1.3 mm females, p = 0.0079), flexion (113° ± 18° males/120° ± 17° females, p = 0.0029), and internal rotation (23° ± 13° males/29° ± 12° females, p = 0.0155). Significant differences also existed between side affected in flexion (116° ± 17° right/119° ± 17° left, p = 0.0396) and internal rotation (26° ± 12° right/29° ± 13° left, p = 0.0029). Positive correlation was observed between axial oblique capsular thickness and flexion (r = 0.2345) (p = 0.0229).

CONCLUSIONS

Increased anterior hip capsular thickness at the femoral head-neck correlates with limitations in hip range of motion in FAI. The strength of this relationship may be affected between pathologies, genders, and affected side. Pathologic thickening of the hip capsule may contribute to restricted hip mobility on clinical examination, and elucidation of this relationship may provide guidance into capsular management during hip arthroscopy.

LEVEL OF EVIDENCE

4, retrospective case series.

Arthroscopic Treatment of Iliopsoas Snapping in Patients With Radiographic Acetabular Dysplasia Using Iliopsoas Fractional Lengthening and Capsular Plication

PURPOSE

The purpose of this study was to evaluate the greater than 2-year patient-reported outcomes (PROs) and patient satisfaction of patients who were treated with hip arthroscopy for snapping iliopsoas tendons that were painful with concomitant acetabular dysplasia and who underwent iliopsoas lengthening for symptomatic iliopsoas tendon snapping with concomitant capsular plication and treatment of hip impingement. Secondary measures included observation of the change in the Tönnis grade at greater than 2 years' follow-up.

METHODS

Between July 2009 and December 2011, data on patients with a lateral center-edge angle (LCEA) of less than 25° (range, 19°-24°) who underwent hip arthroscopy with central-compartment iliopsoas fractional lengthening and capsular plication were prospectively collected and retrospectively reviewed. Interportal capsular repair was performed using between 2 and 5 simple sutures. Patients also underwent procedures to treat hip impingement pathology. All patients had preoperative and minimum 2-year postoperative PRO measures: modified Harris Hip Score, Hip Outcome Score-Activities of Daily Living subscale, Hip Outcome Score-Sports-Specific subscale, and Non-arthritic Hip Score. The visual analog scale score and patient satisfaction with surgery (from 0 to 10) were also collected. Radiographs were analyzed preoperatively and at latest follow-up to assess progression of the Tönnis grade.

RESULTS

We analyzed 32 patients who met the inclusion criteria (30 female and 2 male patients; mean age, 25 years). The mean LCEA and anterior center-edge angle were 21.6° and 25.5°, respectively. Four patients required revision arthroscopy for labral retears. Among the 28 patients who did not undergo revision surgery, the modified Harris Hip Score, Hip Outcome Score-Activities of Daily Living subscale, Hip Outcome Score-Sports-Specific subscale, and Non-arthritic Hip Score improved from 68.7 to 83.5, from 64.9 to 86.6, from 71.6 to 86.7, and from 52.6 to 75.8, respectively (P < .001). The visual analog scale score improved from 5.6 preoperatively to 1.9 at latest follow-up (P < .001). The mean patient satisfaction rating was 8.0. There was no radiographic progression of the Tönnis grade at final follow-up.

CONCLUSIONS

This study showed that patients with an LCEA of less than 25° and associated painful iliopsoas snapping can be treated by addressing concomitant pathology and performing central-compartment fractional lengthening of the iliopsoas tendon with concomitant capsular plication and have high satisfaction, improvement in PROs, and improved pain scores, without significant progression of osteoarthritis.

LEVEL OF EVIDENCE

Level IV, case series.

Should the Capsule Be Repaired or Plicated After Hip Arthroscopy for Labral Tears Associated With Femoroacetabular Impingement or Instability? A Systematic Review

PURPOSE

To critically evaluate the existing literature on hip capsule biomechanics, clinical evidence of instability, and outcomes of capsular management to answer the following question: Should the capsule be repaired or plicated after hip arthroscopy for labral tears associated with femoroacetabular impingement or instability?

METHODS

We used PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines to find articles using PubMed and Embase. Included studies were Level I through V studies and focused on hip capsule biomechanics, postarthroscopic instability, and clinical outcomes. Articles were excluded if they discussed treatment of the hip capsule during arthroplasty, dislocations without a history of arthroscopy, and pre-existing conditions. The Methodological Index for Non-randomized Studies (MINORS) was used for quality assessment of clinical outcome studies.

RESULTS

A total of 34 articles were included: 15 biomechanical studies, 9 instability case reports, and 10 outcome studies. There is consensus from biomechanical studies that the capsule is an important stabilizer of the hip and repairing it provides better stability than when unrepaired. Case reports of instability have raised concerns about capsular management during the index procedure to decrease the complications associated with this problem. Furthermore, outcome studies suggest that there may be an advantage of capsular closure versus capsulotomy during hip arthroscopy for nonarthritic patients.

CONCLUSIONS

Short-term outcome studies suggest that capsular closure is safe and effective in nonarthritic patients undergoing hip arthroscopic procedures and may yield superior outcomes compared with unrepaired capsulotomy. Moreover, biomechanical evidence strongly supports the role of capsular repair in maintaining stability of the hip. In patients with stiffness or inflammatory hip disorders, a release may be appropriate. In patients who have signs and symptoms of instability, there is existing evidence that capsular plication may be associated with significant improvement in patient-reported outcomes. Although the multiple procedures performed in combination with capsular treatment present confounding variables, current evidence appears to support routine capsular closure in most cases and to support capsular plication in cases of instability or borderline dysplasia.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II through IV studies.

Outcomes of Hip Arthroscopy in Competitive Athletes

PURPOSE

To evaluate the minimum 2-year postoperative clinical outcomes and the rate of return to sports in athletes who underwent capsular plication for the treatment of ligamentous laxity and/or borderline dysplasia during hip arthroscopy for the treatment of femoroacetabular impingement and labral pathology.

METHODS

Since 2008, data were prospectively collected on patients who underwent hip arthroscopy for the treatment of femoroacetabular impingement and/or labral tears. Inclusion criteria were as follows: athlete at the high school, collegiate, or professional levels preoperatively, underwent capsular plication, and preoperatively recorded patient-reported outcome scores including modified Harris hip score (mHHS), nonarthritic athletic hip score (NAHS), hip outcome score-sports-specific subscale (HOS-SSS), and visual analog scale (VAS). Exclusion criteria were as follows: <16 years old, preoperative Tönnis grade >1, and previous hip conditions. Sports activity and competitive levels were collected at a minimum of 2 years postoperatively.

RESULTS

Fifty-one hips (49 patients) met the inclusion criteria, and 41 hips (39 patients) had minimum 2-year follow-up (80.4% follow-up). Mean mHHS increased from 67.1 preoperatively to 83.5 (P < .0001). Mean NAHS increased from 66.8 to 88.8 (P < .0001). Mean HOS-SSS improved from 46.8 to 80.1 (P < .0001). Mean VAS decreased from 5.1 to 1.7 (P < .0001). Thirty-five (85.4%) hip arthroscopies allowed the patients to return to sports at follow-up. Thirty-four (82.9%) hip arthroscopies allowed the patients to maintain their competitive physical abilities at follow-up.

CONCLUSIONS

Patient-reported outcomes and VAS in athletes significantly improved at a minimum of 2 years after capsular plication as a part of hip arthroscopy addressing varying pathologies. In addition, most patients returned to sports at similar or higher competitive levels. These results suggest that capsular plication is a favorable treatment option in athletes with ligamentous laxity and/or borderline dysplasia.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Screw Fixation of Os Acetabuli: An Arthroscopic Technique

An os acetabuli (OA) increases the contact area and surface area of the acetabulum and is important to maintain congruity of the hip joint. Thus preservation of this ossicle is important to prevent loss of contact area and ensure containment of the femoral head. We describe an all-arthroscopic approach to the fixation of OA with a compression screw. Initially, the fibrous tissue is debrided between the acetabular rim and the OA, a guidewire is placed through the OA up to the acetabular rim, and a screw is inserted over the wire. Compression of the OA is achieved with bone-to-bone contact. This technique prevents loss of femoral head coverage, reducing the risk of subluxation and subsequent osteoarthritis.

Hip Capsular Closure: A Biomechanical Analysis of Failure Torque

BACKGROUND

Hip capsulotomy is routinely performed during arthroscopic surgery to achieve adequate exposure of the joint. Iatrogenic instability can result after hip arthroscopic surgery because of capsular insufficiency, which can be avoided with effective closure of the hip capsule. There is currently no consensus in the literature regarding the optimal quantity of sutures upon capsular closure to achieve maximal stability postoperatively. Purpose/Hypothesis: The purpose of this study was to determine the failure torques of 1-, 2-, and 3-suture constructs for hip capsular closure to resist external rotation and extension after standard anterosuperior interportal capsulotomy (12 to 3 o'clock). Additionally, the degree of external rotation at which the suture constructs failed was recorded. The null hypothesis of this study was that no significant differences with respect to the failure torque would be found between the 3 repair constructs.

STUDY DESIGN

Controlled laboratory study.

METHODS

Nine pairs (n = 18) of fresh-frozen human cadaveric hemipelvises underwent anterosuperior interportal capsulotomy, which were repaired with 1, 2, or 3 side-to-side sutures. Each hip was secured in a dynamic biaxial testing machine and underwent a cyclic external rotation preconditioning protocol, followed by external rotation to failure.

RESULTS

The failure torque of the 1-suture hip capsular closure construct was significantly less than that of the 3-suture construct. The median failure torque for the 1-suture construct was 67.4 N·m (range, 47.4-73.6 N·m). The median failure torque was 85.7 N·m (range, 56.9-99.1 N·m) for the 2-suture construct and 91.7 N·m (range, 74.7-99.0 N·m) for the 3-suture construct. All 3 repair constructs exhibited a median 36° (range, 22°-64°) of external rotation at the failure torque.

CONCLUSION

The most important finding of this study was that the 2- and 3-suture constructs resulted in comparable biomechanical failure torques when external rotation forces were applied to conventional hip capsulotomy in a cadaveric model. The 3-suture construct was significantly stronger than the 1-suture construct; however, there was not a significant difference between the 2- and 3-suture constructs. Additionally, all constructs failed at approximately 36° of external rotation.

CLINICAL RELEVANCE

Re-establishing the native anatomy of the hip capsule after hip arthroscopic surgery has been reported to result in improved outcomes and reduce the risk of iatrogenic instability. Therefore, adequate capsular closure is important to restore proper hip biomechanics, and postoperative precautions limiting external rotation should be utilized to protect the repair.

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 hip capsuloligamentous reconstruction with Achilles allograft following gross hip instability post-arthroscopy

The increasing use of hip arthroscopy has led to further development in our understanding of hip anatomy and potential post-operative complications. Iatrogenic gross hip instability following hip arthroscopy is a concerning complication described in recent orthopaedic literature. Post-arthroscopy hip instability is thought to be multifactorial, related to a variety of patient, surgical and post-operative factors. Given its infrequency, there is scarcity of literature describing appropriate surgical management and operative technique for addressing this instability. This study reports a case of gross hip instability following hip arthroscopy, describing a novel technique of management through anterior hip capsuloligamentous reconstruction with Achilles tendon allograft. Level of evidence V, Case Study.

Microinstability of the hip: a previously unrecognized pathology

BACKGROUND

Hip microinstability is an established diagnosis; however, its occurrence is still debated by many physicians. Diagnosis of hip microinstability is often challenging, due to a lack of specific signs or symptoms, and patients may remain undiagnosed for long periods. This may lead to early manifestation of degenerative joint disease. Consequently, careful patient and family history must be obtained and diagnostic imaging should follow. After a thorough clinical evaluation of the patient with suspected hip microinstability, the physician should focus on how to improve symptoms and functionality in daily and sports activities.

PURPOSE

The purpose of this review article was to give a current update regarding this diagnosis and to provide a complete diagnostic approach in order to effectively treat hip microinstability.

METHODS

We reviewed the literature on the diagnosis, the non-operative and operative indications for the treatment of this complex and often misdiagnosed pathology.

CONCLUSION

Conservative treatment is considered the best initial approach, though, surgical intervention should be considered if symptoms persist or other hip pathology exists. Successful surgical intervention, such as hip arthroscopy, should focus on restoring the normal anatomy of the hip joint in order to regain its functionality. The role of the hip joint capsule has gained particular research interest during the last years, and its repair or reconstruction during hip arthroscopy is considered necessary in order to avoid iatrogenic hip microinstability. Various capsular closure/plication techniques have been developed towards this direction with encouraging results.

LEVEL OF EVIDENCE

V.

The Stress-Strain Data of the Hip Capsule Ligaments Are Gender and Side Independent Suggesting a Smaller Contribution to Passive Stiffness

Background

The ligaments in coherence with the capsule of the hip joint are known to contribute to hip stability. Nevertheless, the contribution of the mechanical properties of the ligaments and gender- or side-specific differences are still not completely clear. To date, comparisons of the hip capsule ligaments to other tissues stabilizing the pelvis and hip joint, e.g. the iliotibial tract, were not performed.

Materials & Methods

Hip capsule ligaments were obtained from 17 human cadavers (9 females, 7 males, 13 left and 8 right sides, mean age 83.65 ± 10.54 years). 18 iliofemoral, 9 ischiofemoral and 17 pubofemoral ligaments were prepared. Uniaxial stress-strain properties were obtained from the load-deformation curves before the secant elastic modulus was computed. Strain, elastic modulus and cross sections were compared.

Results

Strain and elastic modulus revealed no significant differences between the iliofemoral (strain 129.8 ± 11.1%, elastic modulus 48.8 ± 21.4 N/mm²), ischiofemoral (strain 128.7 ± 13.7%, elastic modulus 37.5 ± 20.4 N/mm²) and pubofemoral (strain 133.2 ± 23.7%, elastic modulus 49.0 ± 32.1 N/mm²) ligaments. The iliofemoral ligament (53.5 ± 15.1 mm²) yielded a significantly higher cross section compared to the ischiofemoral (19.2 ± 13.2 mm²) and pubofemoral (15.2 ± 7.2 mm²) ligament. No significant gender- or side-specific differences were determined. A comparison to the published data on the iliotibial tract revealed lower elasticity and less variation in the ligaments of the hip joint.

Conclusion

Comparison of the mechanical data of the hip joint ligaments indicates that their role may likely exceed a function as a mechanical stabilizer. Uniaxial testing of interwoven collagen fibers might lead to a misinterpretation of the mechanical properties of the hip capsule ligaments in the given setup, concealing its uniaxial properties. This underlines the need for a polyaxial test setup using fresh and non-embalmed tissues.

Arthroscopic Capsular Reconstruction of the Hip With Acellular Dermal Extracellular Matrix: Surgical Technique

Atraumatic instability of the hip has become an increasingly studied occurrence in recent years. There are several established surgical techniques that help restore stability of the native hip joint. In some cases, these procedures are not an option. As the phenomenon has become recognized more frequently, a greater number of revision surgeries are warranted in patients with ligamentous laxity. A durable solution for irreparable microinstability needs to be formulated to address this vulnerable patient demographic. We describe the surgical technique for capsular reconstruction with acellular dermal extracellular matrix.

Anatomic Hip Capsular Reconstruction With Separate Suture Anchors

The number of reports on the use of capsule suturing techniques during hip arthroscopy has increased in the last few years because of the important function played by the iliofemoral ligament (IFL). This study describes an arthroscopic technique whereby the hip capsule is opened by a limited vertical dissection of both the capsule itself and the IFL from their footprint on the acetabular rim, and the capsulolabral junction and the IFL's deep fibers are released. After the intra-articular procedure, the capsule is closed through 2 to 4 side-to-side sutures in the vertical arm of the capsulotomy and 1 to 2 suture anchors with sutures are passed through either side of the capsular confluence. This technique prevents a full transverse section of the IFL and allows complete capsular closure through reconstruction of the capsular footprint.

Hip Capsular Reconstruction Using Dermal Allograft

Because hip arthroscopic procedures are increasing in number, complications related to the operation itself are starting to emerge. Whereas the capsule has been recognized as an important static stabilizer for the hip, it has not been until recently that surgeons have realized the importance of its preservation and restoration. Disruption of the capsule during arthroscopic procedures is a potential contributor to postoperative iatrogenic hip instability. In cases of a symptomatic deficient capsule, a capsular reconstruction is mandatory because instability may lead to detrimental chondral and labral changes. The purpose of this report was to describe our technique for arthroscopic hip capsular reconstruction using dermal allograft.

Capsular Management in Hip Arthroscopy: An Anatomic, Biomechanical, and Technical Review

Hip arthroscopy has become an increasingly utilized surgical technique for the treatment of the young, active patients with hip pain. The clinical outcomes of hip arthroscopy in this patient population have been largely successful; however, there is increasing interest in the contribution of hip capsule in postoperative clinical and functional outcomes. The structure and function of the normal hip capsule will be reviewed. Capsular contributions to hip stability will be discussed in the setting of hip arthroscopy with an emphasis on diagnosis-based considerations. Lastly, clinical outcomes following hip arthroscopy will be discussed as they relate to capsular management.

Arthroscopic capsule reconstruction in the hip using iliotibial band allograft

The hip capsule has been identified as an important static stabilizer of the hip joint. Despite the intrinsic bony stability of the hip socket, the capsule plays a key role in hip stability, particularly at the extremes of motion, and the iliofemoral ligament is the most important stabilizer in extension and external rotation. Patients who do not undergo capsular closure or plication may continue to complain of hip pain and dysfunction postoperatively, likely because of microinstability or muscle invagination into the capsular defect, and high-resolution magnetic resonance imaging or magnetic resonance arthrography will identify the capsular defect. Seen primarily in the revision setting, capsular defects can cause recurrent stress at the chondrolabral junction. An attempt at secondary closure can be challenging because of capsular limb adherence to the surrounding soft tissues. Therefore reconstruction may be the only possible surgical solution for this problem. We describe our new surgical technique for arthroscopic hip capsular reconstruction using iliotibial band allograft.