Hip Capsule Research Articles

A rare case of para-articular chondroma of the hip joint in an adolescent

Extraskeletal chondromas are unusual benign skeletal tumors which do not arise from the bone or perisoteum. They are predisposed to occur in adults usually around the knee joint. We report a rare form of Extraskeletal chondroma arising from the outer layer of the capsule of the hip joint in an adolescent male which was excised surgically and it turned out to be a para-articular chondroma of the hip joint. In conclusion, ESPAOC lesions are extremely rare. It requires a thorough clinical examination and radiographic investigation to diagnose these tumors. The treatment is surgical excision of the tumor mass. A total excision might not be possible in all patients such as ours. In these cases, the part of the tumor causing symptomatic disconcern might be excised to allow functional range of movements of the affected joint.

Microinstability of the hip: a previously unrecognized pathology.

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

Effect of soft-tissue impingement on range of motion during posterior approach Total Hip Arthroplasty: an in vivo measurement study

Purpose: While implant impingement and bony impingement have been recognized as causes of poor outcomes in total hip arthroplasty (THA), reports of soft-tissue impingement are rare. To clarify the issue, the effect of anterior capsule resection on hip range of motion (ROM) was quantitatively measured in vivo during posterior approach THA using a CT-based hip navigation system.Materials and methods: For 47 patients (51 hips), hip ROM was measured intraoperatively before and after resection of the anterior hip capsule, and the difference was compared.Results: Resection of the anterior hip capsule brought about an average 6° increase of ROM in the direction of flexion with internal rotation and did not markedly change ROM in other directions.Conclusions: During THA through a posterior approach, soft-tissue impingement by the anterior hip capsule can occur. Clinically, we expect that resection of the anterior hip capsule can reduce the risk of posterior instability without increasing the risk of anterior instability.

Biomechanical Effects of Capsular Shift in the Treatment of Hip Microinstability

Background: A capsular shift procedure has been described for the treatment of hip instability; however, the biomechanical effects of such a shift are unknown. Purpose: To create a cadaveric model of hip capsule laxity and evaluate the biomechanical effects of a capsular shift used to treat hip instability on this model. Study Design: Controlled laboratory study. Methods: Eight cadaveric hips with an average age of 58.5 years were tested with a custom hip testing system in 6 conditions: intact, vented, instability, capsulotomy, side-to-side repair, and capsular shift. To create the hip model, the capsule was stretched in extension under 35 N·m of torque for 1 hour in neutral rotation. Measurements included internal and external rotation with 1.5 N·m of torque at 5 positions: 5° of extension and 0°, 15°, 30°, and 45° of flexion for each of the above conditions. The degree of maximum extension with 5 N·m of torque and the amount of femoral distraction with 40 N and 80 N of force were measured. Statistical analysis was performed by use of repeated-measures analysis of variance with Tukey post hoc analysis. Results: The instability state significantly increased internal rotation at all flexion angles and increased distraction compared with the intact state. The capsulotomy condition resulted in significantly increased external rotation and internal rotation at all positions, increased distraction, and maximum extension compared with the intact state. The side-to-side repair condition restored internal rotation back to the instability state but not to the intact state at 5° of extension and 0° of flexion. The capsular shift state significantly decreased internal rotation compared with the instability state at 5° of extension and 0° and 15° of flexion. The capsular shift and side-to-side repair conditions had similar effects on external rotation at all flexion-extension positions. The capsular shift state decreased distraction and maximum extension compared with the instability state, but the side-to-side repair state did not. Conclusion: The hip capsular instability model was shown to have significantly greater total range of motion, external rotation, and extension compared with the intact condition. The greatest effects of capsular shift are seen with internal rotation, maximum extension, and distraction, with minimal effect on external rotation compared with the side-to side repair state. Clinical Relevance: The biomechanical effects of the capsular shift procedure indicate that it can be used to treat hip capsular laxity by decreasing extension and distraction with minimal effect on external rotation.

Biomechanics of the Hip Capsule and Capsule Management Strategies in Hip Arthroscopy.

Recent advances in our understanding of the function of the hip capsule have clarified its importance to normal hip function and kinematics. The iliofemoral ligament is the primary stabilizing structure for controlling anterior translation and external rotation of the hip, and is violated by the arthroscopic interportal capsulotomy. Microinstability of the hip occurring after surgical trauma remains a poorly defined clinical entity. In certain at-risk populations, capsular repair should be considered as part of an arthroscopic hip procedure to achieve optimal outcomes and avoid iatrogenic instability (dislocation or microinstability). Despite a lack of conclusive evidence-based indications, we recommend capsular repair in the settings of borderline hip dysplasia (or dysplastic variants such as increased femoral anteversion), hip hypermobility, connective tissue disorders, and traumatic or atraumatic instability. With careful attention to arthroscopic capsular management, adequate exposure can be achieved and reproducibly allow for an effective capsular repair when indicated.

The Anthropoid Crista Trochanterica and the Hip Joint Capsule.

The tubercle on the posterior aspect of the femoral neck (the crista trochanterica) has been repeatedly remarked upon because of its presence in early fossil apes, yet the function of this tubercle has eluded researchers. The prevailing explanation for the tubercle is that it relates to a strong ischiofemoral ligament, although none of the hypotheses for this bony projection have been systematically evaluated. This study surveyed 41 extant anthropoid species (n = 267 individuals) for the presence of a crista trochanterica. The soft tissue structures of the hip joint were then dissected and described for a sample of anthropoid cadavers (n = 14) in order to evaluate different hypotheses related to function of this tubercle. This study confirmed that the crista trochanterica is found in most cercopithecoids and platyrrhines, and is not present in great apes. The tubercle is rarely present in hylobatids, contrary to prior reports. The ischiofemoral ligament is not usually well-developed in anthropoids and does not fully explain the crista trochanterica morphology, although all cadavers displayed a well-developed zona orbicularis running along the posterior aspect of the joint capsule. The hip joint capsule itself inserted along the crista trochanterica in some individuals, typically those with an elongate crista trochanterica, but was highly variable in regards to the position of the tubercle. The hypotheses for the crista trochanterica are considered within the context of these findings, although the exact function of the tubercle remains unresolved.

Technique to treat iliopsoas irritation after total hip replacement: Thickening of articular hip capsule through an abridged direct anterior approach

Iliopsoas irritation due to acetabular cup component impingement following total hip arthroplasty (THA) is usually treated by infiltration or by distal iliopsoas tenotomy in case of recurrence; however, this can result in an active flexion deficit of the thigh. To prevent this complication, we developed an original technique that we performed between 2012 and 2014 in patients with recurrent impingement following extraarticular corticosteroid injections. This included 5 patients (mean age: 64 [53–75] years old) in whom we performed an ambulatory bursectomy by the Hueter approach and placed a polyglactin 910 (Vicryl™) mesh plate on the entire anterior hip capsule. After a mean follow-up of 12months (9–29months), anterior pain had decreased in all patients with improvement and an increase in the Oxford-12 (mean: 15 points [10–19]), Merle d’Aubigné (mean: 2.5 points [1–5]) and Harris (mean: 18 points [10–29]) scores. No flexion deficits were observed. An infected postoperative hematoma had to be drained but was cured at follow-up. This simple procedure provides satisfactory results and preserves THA function. It does not jeopardize future procedures and is an alternative option in case of unsuccessful conservative treatment.

The Use of Superselective Arteriography in the Evaluation of the Influence of Intracapsular Hip Joint Pressure on the Blood Flow of the Femoral Head

Objective: We aimed to analyze the intracapsular pressure of the hip joint following femoral neck fracture and its relationship to the position of the hip or to traction and (using superselective arteriography) to evaluate the blood supply to the femoral head and the influence of traction and hip position on the blood supply. Subjects and Methods: Twenty-six cases of fresh Garden type I-III femoral neck fractures were enrolled. After being placed in the neutral position, in internal rotation or with traction of 3 and 5 kg, respectively, intracapsular manometric changes were measured. Eight cases underwent superselective arteriography of the medial circumflex femoral artery and its branches under the manometric changes of the hip joint capsule. Results: Twenty-four to 48 h after the injury, the intracapsular pressure was significantly higher on the fractured side than on the normal side. The mean pressure was 28.41 ± 9.339 mm Hg in fully extended hips in the neutral position, 79.92 ± 12.80 mm Hg in internally rotated hips, 51.39 ± 15.41 mm Hg in hips with 3 kg of traction and 64.81 ± 13.56 mm Hg in hips with 5 kg of traction. The arteriographic findings revealed that traction and internal rotation reduced the perfusion of the femoral head at the medial circumflex femoral artery and its branches, and also negatively influenced venous reflux. Conclusion: Traction and internal rotation both caused the intracapsular pressure of the hip joint to rise considerably, which reduced the femoral head perfusion and impeded venous reflux. This could lead to avascular necrosis of the femoral head.

Arthroscopic Capsular Repair for Symptomatic Hip Instability After Previous Hip Arthroscopic Surgery

Background: Management of the hip capsule has been a topic of recent debate in hip arthroscopic surgery. Postoperative instability after hip arthroscopic surgery has been reported and can lead to poor outcomes. Purpose: To determine the outcome of patients diagnosed with symptomatic instability after hip arthroscopic surgery at a minimum of 12 months and 24 months after revision surgery for capsular repair. Study Design: Case series; Level of evidence, 4. Methods: In a cohort of approximately 1100 patients who underwent hip arthroscopic surgery, 33 patients (33 hips) developed symptomatic instability requiring a revision surgery. Two patients suffered anterior dislocations following their initial surgery. Radiographs were reviewed to evaluate for acetabular dysplasia. Three patients were lost to follow-up and 10 patients were excluded as they were <1 year out from the revision surgery. A total of 20 patients (18 female, 2 male) completed a preoperative and postoperative modified Harris Hip Score (mHHS) and Hip Outcome Score (HOS) at a minimum of 12 months. Eleven of these patients had a minimum follow-up of 24 months. All patients filled out a Likert scale of perceived improvement in physical ability at final follow-up. Results: The mean age of the patients was 29.7 years (range, 15.2-55.5 years). The mean lateral center-edge angle was 25°, and the mean acetabular index was 7° before revision. All patients underwent interportal capsulotomy during the index arthroscopic procedure. After their index arthroscopic procedures, patients had minimal improvement at a mean of 19.1 months postoperatively on the mHHS (from 57.1 to 57.6; P = .423), HOS-Activities of Daily Living (ADL) (from 62.7 to 66.4; P = .260), and HOS-Sports (from 42.0 to 39.1; P = .800). For the patients with a minimum 1-year follow-up after revision surgery (n = 20; mean follow-up, 21.3 months), the mean mHHS (from 57.6 preoperatively to 85.8 at final follow-up; P < .001), HOS-ADL (from 66.4 to 85.7; P < .001), and HOS-Sports (from 39.1 to 79.8; P < .001) all improved significantly. The results were similar when looking at only the patients with a minimum 2-year follow-up after revision surgery (n = 11; mean follow-up, 26.1 months); the mean mHHS (from 56.0 preoperatively to 91.5 at final follow-up; P = .001), HOS-ADL (from 68.3 to 89.9; P = .009), and HOS-Sports (from 35.7 to 87.9; P = .001) all improved significantly. When comparing patients with isolated capsular repair to those with additional procedures performed, there were no differences between the groups (all P > .05). At final follow-up, all but 1 patient had improved overall physical ability levels. Conclusion: Revision hip arthroscopic surgery for capsular repair in patients with symptomatic instability after hip arthroscopic surgery provides good functional outcomes at a minimum of 1 and 2 years postoperatively.

The envelope of passive motion allowed by the capsular ligaments of the hip

Laboratory data indicate the hip capsular ligaments prevent excessive range of motion, may protect the joint against adverse edge loading and contribute to synovial fluid replenishment at the cartilage surfaces of the joint. However, their repair after joint preserving or arthroplasty surgery is not routine. In order to restore their biomechanical function after hip surgery, the positions of the hip at which the ligaments engage together with their tensions when they engage is required. Nine cadaveric left hips without pathology were skeletonised except for the hip joint capsule and mounted in a six-degrees-of-freedom testing rig. A 5Nm torque was applied to all rotational degrees-of-freedom separately to quantify the passive restraint envelope throughout the available range of motion with the hip functionally loaded. The capsular ligaments allowed the hip to internally/externally rotate with a large range of un-resisted rotation (up to 50±10°) in mid-flexion and mid-ab/adduction but this was reduced towards the limits of flexion/extension and ab/adduction such that there was a near-zero slack region in some positions (p<0.014). The slack region was not symmetrical; the mid-slack point was found with internal rotation in extension and external rotation in flexion (p<0.001). The torsional stiffness of the capsular ligamentous restraint averaged 0.8±0.3Nm/° and was greater in positions where there were large slack regions. These data provide a target for restoration of normal capsular ligament tensions after joint preserving hip surgery. Ligament repair is technically demanding, particularly for arthroscopic procedures, but failing to restore their function may increase the risk of osteoarthritic degeneration.

Supercapsular percutaneously-assisted total hip arthroplasty: radiographic outcomes and surgical technique.

The supercapsular percutaneously-assisted total hip (SuperPATH(®)) approach for total hip arthroplasty (THA) was developed to promote early mobilization and greater range of motion, physiologic gait kinematics and improved pain control. The superpath approach is a hybrid of the Superior Capsulotomy (SuperCap(®)) approach and the percutaneously assisted total hip (PATH(®)) technique. Postoperative radiographs of 66 consecutive patients from the first 100 patients who underwent the SuperPATH approach were analysed by an independent third party for component position and seating, femoral offset and leg length. A detailed description of preoperative and postoperative preparation, soft tissue dissection, preparation of the femoral canal and acetabulum, and implant positioning is also provided with figures to illustrate. All components in this case series were well seated and position deemed optimal. Leg lengths were measured to within 5 mm of the contralateral side and mean acetabular abduction angle was 40.13° (SD 6.30°). Through preservation of the external rotators, hip capsule, and abductor integrity, the SuperPATH approach for THA maximally preserves the surrounding soft tissue envelope. Implant position was optimal within the 'learning curve' of the first 100 cases for described THA safe zones. Long term outcome data for the SuperPATH approach are being collected as part of an ongoing study to compare to favourable short and mid-term results.

Atraumatic Hip Instability in Patients With Joint Hypermobility

Atraumatic hip instability is a recently described source of hip pain and disability. Hip instability may be caused by bony dysplasia, benign or inherited joint hypermobility syndromes, or iatrogenic damage to the hip capsule during arthroscopy. A thorough understanding of hip capsular anatomy is essential to the management of instability, and is reviewed in this study. In addition, the essential historical, clinical, and radiographic findings of atraumatic hip instability are presented. Critical concepts include early referral in the presence of inherited joint hypermobility syndromes, the use of validated criteria for detection of benign joint hypermobility, and systematic efforts to understand the cause of instability before initiating treatment. Although nonoperative measures can successfully treat atraumatic hip instability, surgical intervention is often warranted, and the technical principles of hip capsular plication are described in detail.

Capsular Suspension Technique for Hip Arthroscopy

Hip arthroscopy has recently become a common procedure to treat central and peripheral hip pathology. Capsulotomies are necessary in these procedures, and negotiating adequate visualization, as well as capsular preservation, is a challenge. We describe a capsular suspension technique that allows for adequate visualization of the central and peripheral compartments while facilitating preservation of the native hip capsule. This technique eliminates the need for additional personnel for retraction, potentially decreases iatrogenic hip injury, eliminates the need for excessive capsular debridement, and allows for capsular closure under minimal tension.

Biomechanical Effect of Capsular Shift in the Treatment of Hip Microinstability. Creation and Testing of a Novel Hip Instability Model

Objectives:The objective of the study was to create a cadaveric model of hip capsule laxity and evaluate the biomechanical effects of a capsular shift used to treat hip instability on this model.Methods:Eight fresh frozen cadaveric hips, average age 58.5, were tested with a custom hip jig. To create the hip laxity model, the capsule was stretched in extension under 35Nm of torque for 1 hour in neutral rotation. Specimens went through a series of six testing conditions: intact, vented, stretched, capsulotomy, side to side repair, and capsular shift. Specimens were tested in internal (IR) and external (ER) rotational range of motion under 1.5 Nm of torque at 5 positions: 5° extension, 0°, 15°, 30° and 45° flexion. Maximum extension was measured at 5Nm torque, and femoral distraction under 40N and 80N of force. Following creation of the instability model, capsulotomy was performed just distal to and in line with the labrum from 12 o’clock to 4 o’clock through the entire substance of the iliofemoral ligament. Capsulotomies underwent two repairs, including a 1 cm capsular shift technique and side to side repair using #2 vicryl. Statistical analysis was performed using repeated measures ANOVA with TUKEY post-hoc analysis.Results:Analysis of the “stretched” state showed significantly increased IR at 5° ext, 0° flex, 15° flex, and 30° flex and increased distraction at 40N and 80N as compared to intact (Figure 1)(Table 1). Max extension increased by 6.6° between intact and stretched, however this was not statistically significant. Capsulotomy condition significantly increased ER and IR from intact at all flexion-extension positions. Furthermore, capsulotomy increased distraction at 40N and 80N, as well as max extension, as compared to intact. The repair restored IR back to the stretched state but not to the intact state at 5° ext and 0° flex (19.6° vs 24.5° and 21.8° vs 26.4°, respectively). The capsular shift significantly decreased IR compared to stretched state at 5° ext, 0°, and 15° flex, and at 5° ext and 0° compared to the vented state. Capsular shift restricted IR significantly more than repair at 5° ext, 0° flex, and 15° flex. Capsule shift and repair had similar effects on ER. Distraction distance at 40N and 80N was greater in the repair compared to the shift but this was not statistically significant. The capsular shift decreased distraction as compared to the stretched state but the repair did not. Maximum extension was significantly reduced back to the intact/vented state from the laxity state in the capsular shift but not in the repair.Conclusion:The instability model (stretched) was shown to have significantly greater range of motion, extension, and distraction than the intact condition. The greatest effects of capsular shift are seen with internal rotation, extension, and distraction with minimal effect on external rotation. The biomechanical effects of the capsular shift procedure in hip laxity patients show that its use can safely treat pathologic hip capsular laxity.

A Matched-Pair Controlled Study of Arthroscopic Psoas Tenotomy with Minimum 2-Year Follow-Up

Objectives:It is unknown whether pateints undergoing tenotomy for painful internal snapping at the time of hip arthroscopy can expect equivalent functional outcome to patients undergoing hip arthroscopy without tenotomy. The contribution of the psoas tendon and hip capsule to hip stability is also currently debated. The purpose of this matched study is to (1) compare two-year outcome scores in a study group who underwent psoas tenotomy to a matched control group who did not have a psoas tenotomy, and (2) perform a subgroup analysis of the study group comparing capsular repair to capsular release.Methods:Between April of 2008 and December of 2012, we prospectively collected data and reviewed 694 hip arthroscopies with a minimum 2 year follow up. A total of 243 patients had undergone psoas tenotomy and comprised the study group available for matching. After a power analysis was performed we matched 50 patients in the control group to 50 patients in the study group. A subgroup analysis of the study group was then performed based on the capsular treatment performed. Twenty five patients who underwent capsular release were compared to 25 patients who underwent capsular repair. The protocol included pre- and post-operative administration of four hip-specific patient-reported outcome (PRO) tools, the visual analog scale (VAS), and patient satisfaction scores.Results:Both the study group (n=50) and control group (n=50) demonstrated a statistically significant improvement in patient-reported outcome (PRO) scores and pain scores at 2-year follow up (p<0.05). No statistical differences in PRO scores, pain scores, or patient satisfaction was observed at 2-years between the study group and the control group as well as between the capsular repair and capsular release subgroups.Conclusion:In patients with painful internal snapping and psoas impingement lesions arthroscopic psoas tenotomy appears to result in similar two-year outcomes to patients not undergoing psoas tenotomy at the time of labral treatment. We were unable to detect a significant role for capsular closure at the time of psoas tenotomy; however, this requires further study.

Development and first validation of a simplified CT-based classification system of soft tissue changes in large-head metal-on-metal total hip replacement: intra- and interrater reliability and association with revision rates in a uniform cohort of 664 arthroplasties.

After implantation of a metal-on-metal total hip arthroplasty (MoM THA), a large incidence of pseudotumor formation has been described recently. Several centers have invited patients for follow-up in order to screen for pseudotumor formation. The spectrum of abnormalities found by CT in MoM THA patients can be unfamiliar to radiologists and orthopedic surgeons. Previously, a CT five-point grading scale has been published. In this paper, a simplification into a three-point classification system gives insight in the morphological distinction of abnormalities of the postoperative hip capsule in MoM implants in relation to the decision for revision. The reliability of this simplified classification regarding intra- and interrater reliability and its association with revision rate is investigated and discussed. All patients who underwent MoM THA in our hospital were invited for screening. Various clinical measures and CT scan were obtained in a cross-sectional fashion. A decision on revision surgery was made shortly after screening. CT scans were read in 582 patients, of which 82 patients were treated bilaterally. CT scans were independently single read by two board-certified radiologists and classified into categories I-V. In a second meeting, consensus was obtained. Categories were subsequently rubricated in class A (categories I and II), B (category III), and C (categories IV and V). Intra- and inter-radiologist agreement on MoM pathology was assessed by means of the weighted Cohen's kappa. Categorical data were presented as n (%), and tested by means of Fisher's exact test. Continuous data were presented as median (min-max) and tested by means of Mann-Whitney U test (two group comparison) or Kruskal-Wallis test (three group comparison). Logistic regression analysis was performed in order to study independence of CT class for association with revision surgery. Univariate statistically significant variables were entered in a multiple model. All statistical analysis was performed two-tailed using alpha 5% as the significance level. In total, 664 scores from 664 MoM hips obtained by two observers were available for analyses. Interobserver reliability for the non-simplified version (I-V) was κw = 0.71 (95% CI: 0.62-0.79), which indicates good agreement between the two musculoskeletal radiologists. Intra- and interobserver reliability for the simplified version (A-C) were respectively κw 0.78 (95% CI: 0.68-0.87), and κw = 0.71 (95% CI: 0.65-0.76). This indicates good agreement within and between the two observers. The simplified A-C version is significantly associated with revision exclusively due to MoM pathology, in both patients with unilateral MoM THA (p < 0.001) and patients with bilateral MoM THA (p < 0.044). The simplified A-C version is associated with several clinical measures. In patients with unilateral MoM THA, with or without contralateral THA, in situ time (p < 0.008), cobalt and chromium (p < 0.001) were statistically significant. In patients with bilateral MoM, cobalt (p < 0.001) and chromium (p < 0.027) were statistically significant. Revision is significantly associated with cup size (p < 0.001), anteversion of the cup (p < 0.004), serum ion levels of cobalt and chromium (p < 0.001) and the adapted classification system (p < 0.001). In univariate logistic regression analysis on revision, cup, anteversion of the cup, cobalt-chromium ion serum levels, and the simplified (A-C) CT category system were statistically significant. The simplified (A-C) CT category system was an independent associate of revision, in several multiple logistic regression models. The presented simplified CT grading system (A-C) in its first clinical validation on 48- and 64-multislice systems is reliable, showing good intra- and interrater reliability and is independently associated with revision surgery.

Microinstability of the hip-it does exist: etiology, diagnosis and treatment.

Symptomatic hip microinstability is now recognized as a potential cause of pain and disability in young patients. Causes of hip microinstability include underlying bony or soft tissue abnormalities and iatrogenic injuries of the hip capsule; however, many patients lack a clear underlying etiology. Treatment usually begins with an extensive course of non-operative management with an emphasis on activity modification and physical therapy. Surgical intervention should focus on treatment of the underlying cause as well as any associated intra-articular pathology. In many cases, arthroscopic suture plication can be considered when bony deficiency is not the cause. In this article, we will review the spectrum of symptomatic hip microinstability with a focus on the relevant anatomy, etiology, diagnosis and various treatment options.

Anatomy of the hip capsule and pericapsular structures: A cadaveric study.

The anatomical literature contains relatively little qualitative or quantitative information regarding the anatomy of the hip joint capsule and its relationship to the surrounding pericapsular structures. We aimed to provide a detailed description of the anatomy of these relationships in a cadaveric study. Dissections of 11 nonpaired, fresh-frozen cadaveric hips were performed, documenting capsular dimensions and attachments to pericapsular structures including the rectus femoris, gluteus minimus, iliocapsularis, and piriformis and short external rotator muscles. Tendon footprints of these pericapsular muscles were measured, as well as their distance from reproducible bony landmarks. The thickest portion of the hip capsule is posterosuperiorly and superiorly near its acetabular origin, while the thinnest portion is posteriorly and posteroinferiorly near its femoral insertion. The piriformis has no capsular contribution; however, the reflected head of the rectus femoris, gluteus minimus, iliocapsularis, and external rotator tendons all demonstrate consistent capsular adhesions. There are complex associations among these structures, yet the surrounding layers of the capsule are confluent in predictable relationships. Knowledge of the intricate relationship between the hip capsule and pericapsular structures presented here will be useful for surgeons as they perform the precise and specific capsular releases required by various operative procedures. This study also provides information that can lead to further biomechanical, radiographic, and clinical studies on these structures.

Biomechanical Evaluation of Capsulotomy, Capsulectomy, and Capsular Repair on Hip Rotation

To determine the effect of different types of capsulotomies on hip rotational biomechanical characteristics. Seven fresh-frozen cadaveric hip specimens were thawed and dissected, leaving the hip capsule and labrum intact. The femur was transected and potted, and each specimen was placed in a custom loading apparatus that allowed for adjustment of flexion, extension, and axial rotation of the femur. Six reflective infrared markers were attached to the specimens to track the motion of the femoral head with respect to the acetabulum in real time, and external rotation was produced by applying a torque of 10 Nm to the hip specimens. Data analysis was performed using the 3-dimensional position of the markers in space. The specimens were tested in neutral flexion and 40° of flexion in the following capsular states: intact, interportal capsulotomy, T-capsulotomy, repaired capsulotomy, and capsulectomy. Paired t tests and analysis of variance were used with an α value of .05 set as significant. With the hip in neutral flexion, there was increased external rotation with a T-capsulotomy (91.1° ± 20.3°, P= .029) and capsulectomy (91.9° ± 19.6°, P= .015) compared with the intact hip (83.2° ± 20.5°). After complete repair of the T-capsulotomy (87.4° ± 20.6°), there was no significant difference in external rotation compared with the intact hip. No significant differences were seen between groups at 40° of hip flexion. A T-capsulotomy showed significantly increased external rotation versus the intact and interportal capsulotomy states. The repaired T-capsulotomy restored the rotational profile back to the native state. Many methods of capsular treatment during hip arthroscopy exist. Capsulotomy and capsulectomy do not restore the external rotation restraint of the hip back to its native state.

A New Technique in Revision Hip Arthroplasty for Vancouver B Periprosthetic Fractures

We describe a new revision technique for Vancouver B periprosthetic hip fractures that leaves the original acetabular components in situ and causes minimal damage to the hip capsule. Twenty-eight patients, average age 79, with Vancouver B periprosthetic fracture had femoral component revision using