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.

The Hip-Spine Effect: A Biomechanical Study of Ischiofemoral Impingement Effect on Lumbar Facet Joints.

PURPOSE: To assess the relation between ischiofemoral impingement (IFI) and lumbar facet joint load during hip extension in cadavers. METHODS: Twelve hips in 6 fresh T1-to-toes cadaveric specimens were tested. A complete pretesting imaging evaluation was performed using computed tomography scan. Cadavers were positioned in lateral decubitus and fixed to a dissection table. Both legs were placed on a frame in a simulated walking position. Through a posterior lumbar spine approach L3-4 and L4-5 facet joints were dissected bilaterally. In addition, through a posterolateral approach to the hip, the space between the ischium and the lesser trochanter was dissected and measured. Ultrasensitive, and previously validated, piezoresistive force sensors were placed in lumbar facet joints of L3-4 and L4-5. Lumbar facet loads during hip extension were measured in native hip conditions and after simulating IFI by performing lesser trochanter osteotomy and lengthening. Four paired t-tests were performed comparing normal and simulated IFI on the L3-L4 and L4-L5 facet joint loads. RESULTS: After simulating IFI, mean absolute differences of facet joint load were 10.8 N (standard error of the mean [SEM] ±4.53, P = .036) for L3-4 at 10° of hip extension, 13.71 N (SEM ±4.53, P = .012) for L3-4 at 20° of hip extension, 11.49 N (SEM ±4.33, P = .024) for L4-5 at 10° of hip extension, and 6.67 N (SEM ±5.43, P = .245) for L4-5 at 20° of hip extension. A statistically significant increase in L3-4 and L4-5 lumbar facet joint loads of 30.81% was found in the IFI state as compared with the native state during terminal hip extension. CONCLUSIONS: Limited terminal hip extension due to simulated IFI significantly increases L3-4 and L4-5 lumbar facet joint load when compared with non-IFI native hips. CLINICAL RELEVANCE: This biomechanical study directly links IFI to increased lumbar facet loads and supports the clinical findings of IFI causing lumbar pathology. Assessing and treating (open or endoscopic) hip disorders that limit extension could have benefit in patients with concomitant lower back symptoms.

Is there a relationship between psoas impingement and increased trochanteric retroversion?

The concept of psoas impingement secondary to a tight or inflamed iliopsoas tendon causing impingement of the anterior labrum during hip extension has been suggested. The purpose of this study was to assess the relationship between the lesser trochanteric version (LTV) in symptomatic patients with psoas impingement as compared with asymptomatic hips. The femoral neck version (FNV) and LTV were evaluated on axial magnetic resonance imaging, as well as the angle between LTV and FNV. Data from 12 symptomatic patients and 250 asymptomatic patients were analysed. The mean, range and standard deviations were calculated. Independent t-tests were used to determine differences between groups. The lesser trochanteric retroversion was significantly increased in patients with psoas impingement as compared with asymptomatic hips (-31.1° SD ± 6.5 versus -24.2° ± 11.5, P < 0.05). The FNV (9° ± 8.8 versus 14.1° ± 10.7, P > 0.05) and the angle between FNV and LTV (40.2° ± 9.7 versus 38.3° ± 9.6, P > 0.05) were not significantly different between groups. In conclusion, the lesser trochanteric retroversion is significantly increased in patients with psoas impingement as compared with asymptomatic hips.

Iliopsoas tendon insertion footprint with surgical implications in lesser trochanterplasty for treating ischiofemoral impingement: an anatomic study.

The objective of this study was to describe the footprint location of the iliopsoas tendon on the lesser trochanter to clarify the surgical implications of the lesser trochanterplasty for treating ischiofemoral impingement. Ten non-matched, fresh-frozen, cadaveric hemipelvis specimens (average age, 62.4 years; range, 48-84 years; 7 male and 3 female) were included. Registered measures included bony parameters of the lesser trochanter (lesser trochanteric area, distances from the tip to the base in a coordinate system, height and area) and tendinous iliopsoas footprint descriptions (areas and detailed location). The mean height of the lesser trochanter was 13.1 (SD ± 1.8) mm, with female having a smaller lesser trochanter on average (11.3, SD ± 2.0). A double tendinous footprint was found in 7 (70%) specimens. The average area of the single- and double-footprint was 211.2 mm(2) and 187.9 mm(2), respectively. An anterior cortical area with no tendinous insertion on the anterior aspect of lesser trochanter was present in all specimens and measured 4.9 mm (SD ± 0.6) on average. The mean ratio between the bald anterior wall and the lesser trochanter height was 38% (SD ± 0.05). The iliopsoas tendon footprint is double (psoas and iliacus) in most cases and is located on the anteromedial tip of the lesser trochanter. A bald anterior wall on the bottom of the lesser trochanter indicates that a partial or total lesser trochanterplasty for increasing the ischiofemoral space without detaching partially or entirely the iliopsoas tendon is improbable.

Diagnostic accuracy of clinical tests for sciatic nerve entrapment in the gluteal region.

PURPOSE: The purpose of this study was to determine the diagnostic accuracy of the straight leg raise (SLR), active piriformis, and seated piriformis stretch tests in identifying individuals with sciatic nerve entrapment. METHODS: Thirty-three individuals (female = 25 and male = 8) with a mean age of 43 years (range 15-64; SD ± 11 years) were included in the study. Twenty-three subjects had endoscopic findings of sciatic nerve entrapment. Ten subjects without entrapment during endoscopic assessment were used as a control group. The results of the SLR, active piriformis, and seated piriformis stretch tests were retrospectively reviewed for each subject and compared between both groups. The accuracy of these tests for the endoscopic finding of sciatic nerve entrapment was determined by calculating the sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio. RESULTS: The SLR had sensitivity of 0.15, specificity of 0.95, positive likelihood ratio of 3.20, negative likelihood ratio of 0.90, and diagnostic odds ratio of 3.59. The active piriformis test had sensitivity of 0.78, specificity of 0.80, positive likelihood ratio of 3.90, negative likelihood ratio of 0.27, and diagnostic odds ratio of 14.40. The seated piriformis stretch test had sensitivity of 0.52, specificity of 0.90, positive likelihood ratio of 5.22, negative likelihood ratio of 0.53, and diagnostic odds ratio of 9.82. The most accurate findings were obtained when the results of the active piriformis test and seated piriformis stretch test were combined, with sensitivity of 0.91, specificity of 0.80, positive likelihood ratio of 4.57, negative likelihood ratio of 0.11, and diagnostic odds ratio of 42.00. CONCLUSIONS: The active piriformis and seated piriformis stretch tests can be used to help identify patients with and without sciatic nerve entrapment in the deep gluteal region.

Physiological changes as a result of hip arthroscopy performed with traction.

PURPOSE: To evaluate the physiological effects of hip arthroscopy using traction on venous blood flow, nerve conduction, soft-tissue injury, fibrinolysis, and patient pain. METHODS: Thirty subjects were prospectively analyzed in an institutional review board-approved study. The visual analog scale pain score, creatine phosphokinase (CPK)-MM level, and D-dimer test were obtained preoperatively, postoperatively, and 5 days postoperatively. Doppler ultrasound (group A) (n = 15) of femoral and popliteal venous blood flow and somatosensory evoked potentials (SSEPs) (group B) (n = 15) of the posterior tibial nerve and superficial peroneal nerve were monitored intraoperatively. RESULTS: Mean operation and traction times were 131.7 and 27.3 minutes, respectively. During traction (mean, 57.7 lb), decreased blood flow was determined at the popliteal vein (15 of 15 subjects) and femoral vein (4 of 15 subjects). Blood flow returned to baseline after traction in all subjects. Mean CPK-MM levels were 86.0 ± 29.6 mU/mL preoperatively, 232.1 ± 224.6 mU/mL postoperatively, and 138.1 ± 109.3 mU/mL at 5 days postoperatively. The number of subjects positive for D-dimer was 7 preoperatively, 12 postoperatively, and 21 at 5 days postoperatively. SSEPs showed a greater than 50% decrease in amplitude on the operative (8 of 15) and nonoperative (9 of 15) limbs. No significant correlations were determined between visual analog scale pain score, body mass index, CPK-MM level, traction time, or operating room time. CONCLUSIONS: Doppler ultrasound showed decreased blood flow of the popliteal vein with traction, which returned to normal after traction. SSEPs showed changes with and without traction on operative and nonoperative legs. Consideration should be given for knee flexion of the contralateral leg after traction to protect nerve function. Hip arthroscopy resulted in an increase in a positive D-dimer test from immediately postoperatively to postoperative day 5. There is variability in the soft-tissue damage with hip arthroscopy, which is independent of time (<2 hours), body mass index, or pain. Traction affects the vascular and neurologic structures of the operative and nonoperative extremity independent of time. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Effects of filtering methods on muscle and fat cross-sectional area measurement by pQCT: a technical note.

Peripheral quantitative computed tomography (pQCT) is most commonly used for bone density and morphology assessment of the limbs, but it can also be used for soft tissue area quantification by segmenting regions representing different tissues. Scanning and analyzing cross-sectional areas of larger thighs present a special challenge due to increased statistical noise created from fewer detected x-ray photons. The purpose of this technical note is to compare total, muscle and fat cross-sectional area (CSA) measurements of the midthigh with Stratec 3000 pQCT scans using no filter, a weak smoothing filter and a strong smoothing filter to CSA measurements of midthigh MRI scans analyzed by Image J, a public domain image processing program. Nine healthy men and women participated in this study. CSAs did not differ significantly between MRI and strongly filtered pQCT images with per cent differences ranging from -3.1% for muscle to +6.5% for fat. The per cent difference in muscle CSA values between MRI and pQCT with the weak filter (-24.0 ± 38.0%) or no filter (-44.9 ± 22.7%) was strongly related to total thigh CSA (r = 0.78-0.92, p < 0.05). We propose that the midthigh can be assessed for soft tissue area measurements with pQCT, provided that strong smoothing filter is utilized.

Leptin, fat mass, and bone mineral density in healthy pre- and postmenopausal women.

The purpose was to examine relationships between age, fat mass, and bone mineral density (BMD) with resting leptin levels in premenopausal and postmenopausal women. Young (aged 18-30 yr, n=30) and estrogen-deficient postmenopausal (aged 55-75 yr, n=43) women were recruited. Total body and segmental fat mass and bone-free lean body mass (BFLBM) and total body, lumbar spine, and proximal femur BMD were assessed using dual-energy X-ray absorptiometry. Serum-resting, fasted leptin levels were measured by Immunoradiometric Assay (IRMA), and leptin-to-fat mass ratios were calculated. Young and older women had similar amounts of BFLBM, but older women had greater (p<0.05) amounts of fat mass and 35% higher leptin levels. Age differences in leptin concentrations were no longer significant after controlling for fat mass. Older women had significantly (p<0.05) lower hip BMD values. Age was negatively related (r=-0.29, p<0.05) to leptin:trunk fat ratio. Increases in fat mass, not menopause per se, contributes to higher leptin levels in older women. Relationships between leptin and BMD may be age dependent.

The endoscopic treatment of sciatic nerve entrapment/deep gluteal syndrome.

PURPOSE: The purpose of this study was to investigate the historical, clinical, and radiographic presentation of deep gluteal syndrome (DGS) patients, describe the endoscopic anatomy associated with DGS, and assess the effectiveness of endoscopic surgical decompression for DGS. METHODS: Sciatic nerve entrapment was diagnosed in 35 patients (28 women and 7 men). Portals for inspection of the posterior peritrochanteric space (subgluteal space) of the hip were used as well as an auxiliary posterolateral portal. Patients were treated with sciatic nerve decompression by resection of fibrovascular scar bands, piriformis tendon release, obturator internus, or quadratus femoris or by hamstring tendon scarring. Postoperative outcomes were evaluated with the modified Harris Hip Score (MHHS), verbal analog scale (VAS) pain score, and a questionnaire related specifically to sciatic hip pain. RESULTS: The mean patient age was 47 years (range, 20 to 66 years). The mean duration of symptoms was 3.7 years (range, 1 to 23 years). The mean preoperative VAS score was 6.9 ± 2.0, and the mean preoperative MHHS was 54.4 ± 13.1 (range, 25.3 to 79.2). Of the patients, 21 reported preoperative use of narcotics for pain; 2 continued to take narcotics postoperatively (unrelated to initial complaint). The mean time of follow-up was 12 months (range, 6 to 24 months). The mean postoperative MHHS increased to 78.0 and VAS score decreased to 2.4. Eighty-three percent of patients had no postoperative sciatic sit pain (inability to sit for >30 minutes). CONCLUSIONS: Endoscopic decompression of the sciatic nerve appears useful in improving function and diminishing hip pain in sciatic nerve entrapment/DGS.

Effects of combined whole-body vibration and resistance training on muscular strength and bone metabolism in postmenopausal women.

Whole-body vibration (WBV) has been shown to be osteogenic in animal models; however, its application in humans is not clear. The purpose of this study was to examine the effects of an 8-month program involving WBV plus resistance training on bone mineral density (BMD) and bone metabolism in older postmenopausal women. Fifty-five estrogen-deficient postmenopausal women were assigned to a resistance training group (R, n=22), a WBV plus resistance training group (WBVR, n=21), or a control group (CON, n=12). R and WBVR performed upper and lower body resistance exercises 3 days/week at 80% 1 Repetition Maximum (1RM). WBVR received vibration (30-40 Hz, 2-2.8 g) in three different positions preceding the resistance exercises. Daily calcium intake, bone markers (Bone alkaline phosphatase (Bone ALP); C-terminal telopeptide of Type I collagen (CTX), and BMD of the spine, dual femur, forearm, and total body (DXA) were measured at baseline and after the intervention. At baseline, there were no significant group differences in strength, BMD, or bone marker variables. After 8 months of R or WBVR, there were no significant group or time effects in Bone ALP, CTX, or total body, spine, left hip or right trochanter BMD. However, right total hip and right femoral neck BMD significantly (p<0.05) decreased in all groups. A group x time interaction (p<0.05) was detected at radius 33% BMD site, with CON slightly increasing, and WBVR slightly decreasing. R and WBVR significantly (p<0.05) increased 1RM strength for all exercises, while CON generally maintained strength. WBVR had significantly (p<0.05) greater percent increases in muscular strength than R at 4 months for lat pull down, seated row, hip abduction and hip adduction and at 8 months for lat pull down, hip abduction and hip adduction. Bone metabolism in postmenopausal women was not affected by resistance training either with or without WBV. In contrast, the addition of WBV augmented the positive effects of resistance training on muscular strength in these older women.

Evaluation of the hip.

The evaluation of the hip has evolved over generations of orthopedic surgeons. A number of diagnostic tests have been described for specific pathologies that include a common base of maneuvers. A consistent hip examination is conducted to screen the hip, back, abdominal, neurovafscular, and neurologic systems and to find any comorbidities that often exist with complex hip pathology. Provided is a comprehensive evaluation of the hip with proposed descriptions of traditional tests along with provocative maneuvers. Through the use of a common set of diagnostic procedures and terminology, there will be improvement in the accuracy of diagnostic exams for determining hip pathology.

Whole-body vibration augments resistance training effects on body composition in postmenopausal women.

UNLABELLED: Age-related changes in body composition are well-documented with a decrease in lean body mass and a redistribution of body fat generally observed. Resistance training alone has been shown to have positive effects on body composition, however, these benefits may be enhanced by the addition of a vibration stimulus. OBJECTIVE: The purpose of this study was to determine the effects of 8 months of resistance training with and without whole-body vibration (WBV) on body composition in sedentary postmenopausal women. METHODS: Fifty-five women were assigned to resistance only (RG, n=22), vibration plus resistance (VR, n=21) or non-exercising control (CG, n=12) groups. Resistance training (3 sets 10 repetitions 80% strength) was performed using isotonic weight training equipment and whole-body vibration was done with the use of the power plate (Northbrooke, IL) vibration platform for three times per week for 8 months. Total and regional body composition was assessed from the total body DXA scans at baseline (pre) and after 8 months (post) of training. RESULTS: In the VR group, total % body fat decreased from pre- to post-time points (p<0.05), whereas, the CG group had a significant increase in total % body fat (p<0.05). Both training groups exhibited significant increases in bone free lean tissue mass for the total body, arm and trunk regions from pre to post (p<0.05). CG did not show any changes in lean tissue. CONCLUSION: In older women, resistance training alone and with whole-body vibration resulted in positive body composition changes by increasing lean tissue. However, only the combination of resistance training and whole-body vibration was effective for decreasing percent body fat.

Relationships between body composition, muscular strength, and bone mineral density in estrogen-deficient postmenopausal women.

The purpose of this study was to examine relationships between muscular strength, body composition, and bone mineral density (BMD) in untrained postmenopausal women who are not on hormone replacement therapy (HRT). Fifty-five women (age: 63.3+/-0.6yr) completed menstrual history, physical activity, and calcium intake questionnaires. Total and regional body composition and total body, anteroposterior lumbar spine, nondominant forearm, and right proximal femur BMD were measured using dual-energy X-ray absorptiometry (DXA) (GE Lunar Prodigy, Prodigy enCORE software version 10.50.086, Madison, WI). Participants performed strength tests for 3 upper body and 5 lower body resistance exercises. Women with a relative skeletal muscle mass index (RSMI) value less than 5.45 kg/m(2) were defined as a sarcopenia group (SAR). SAR had significantly (p < 0.05) lower total body and forearm BMD compared with those who were not sarcopenic. BMD sites were significantly correlated with upper body strength (UBS) and lower body strength (LBS) (r = 0.28-0.50, p < 0.01), with the strength of relationship being site specific. Strength and fat mass (FM) significantly predicted total body BMD (R(2) = 0.232-0.241, p < 0.05), FM variables predicted spine BMD (R(2) = 0.109-0.140, p < 0.05), and LBS and RSMI predicted hip BMD sites (R(2) = 0.073-0.237, p < 0.05). Body composition variables failed to significantly predict LBS. In conclusion, the contribution of body composition and strength variables to BMD varied by site as FM was more important for total body, forearm and spine BMD, and LBS exerted greater influence on the hip sites.

The function of the hip capsular ligaments: a quantitative report.

PURPOSE: Our purpose was to analyze the anatomy and quantitative contributions of the hip capsular ligaments. METHODS: The stabilizing roles of the medial and lateral arms of the iliofemoral ligament, pubofemoral ligament, and ischiofemoral ligament were examined in 12 matched pairs of fresh-frozen cadaveric hips (6 male and 6 female hips). The motion at the hip joint was measured in internal and external rotation through ranges of motion from 30 degrees flexion to 10 degrees extension along a neutral swing path. The motion was standardized by use of frame stabilization and motion tracking. RESULTS: There is a clear and consistent ligamentous pattern within the hip corresponding to a distinct function and contribution to internal and external rotation. On releasing the ischiofemoral ligament, the greatest gain in range of motion was that of internal rotation. The largest increase of motion by releasing the pubofemoral ligament was observed in external rotation, especially during extension. The release of the medial and lateral arms of the iliofemoral ligament each gave the greatest increase of motion in external rotation, with the lateral arm release providing more range of motion in flexion and in a neutral position. The lateral arm release also showed a significant motion increase in internal rotation, primarily in extension. CONCLUSIONS: The ischiofemoral ligament controls internal rotation in flexion and extension. The lateral arm of the iliofemoral ligament has dual control of external rotation in flexion and both internal and external rotation in extension. The pubofemoral ligament controls external rotation in extension with contributions from the medial and lateral arms of the iliofemoral ligament. Together, these findings can have significant clinical applications. CLINICAL RELEVANCE: When abnormal muscular and osseous pathology can be eliminated as a cause of instability or restrictive range of motion, the understanding of the independent functions of the hip ligaments will aid in defining accurate assessment and nonsurgical and arthroscopic treatment techniques.

Muscle-Bone Interactions Across age in Men.

This study examined the relationship of muscular strength and lean tissue with age-related patterns in bone mineral density (BMD) in men 20-81 years of age. Subjects were assigned to one of three age groups, Young Men (YM), (n = 25, 20-39 yrs), Middle-aged Men (MM) (n = 24, 40-59 yrs), and Older Men (OM) (n = 23, 60-81 yrs). Isotonic and isokinetic strength was assessed for the quadriceps and hamstrings muscle groups. DXA (Lunar DPX-IQ) was used to measure spine, hip, and total body BMD and body composition. OM had significantly lower (p < 0.05) total lean body mass (LBM) than MM and lower leg lean mass (LM) than YM and MM. OM had significantly lower (p < 0.01) BMD than YM and MM at the femoral neck and total hip sites and a higher proportion of OM were osteopenic and osteoporotic at the total hip site. Isotonic and isokinetic strength for both muscle groups was positively related (p < 0.05) with the hip BMD sites (r = 0.38-.67). Leg LM also was positively related to hip BMD (r = 0.37-.58). Multiple Regression analyses determined that age and lean mass (LBM or leg LM) were significant predictors (p < 0.05) of femoral neck, and total hip BMD, while lean mass (LBM or leg LM) was a significant predictor (p < 0.05) of BMD at the spine and trochanter sites. Isotonic and isokinetic leg strength variables were significant predictors (p < 0.05) of the total body, total hip and trochanter BMD. In conclusion, leg strength, leg LM, and total LBM were significant predictors of BMD in men, independent of age. These findings emphasize the importance of maintaining lean body mass for the bone health of aging men. Key PointsOsteoporosis is an important health problem for men.Bone mineral density for the hip was lower in older men compared to their younger and middle-age counterparts. There were age group differences in the prevalence of osteopenia and osteoporosis for the total hip BMD site.Muscular strength and bone-free lean body mass were significant predictors of hip BMD, independent of age, thus reinforcing the importance of contractile forces on skeletal health.Maintenance of muscle mass and strength should be encouraged in aging men for the reduction of osteoporosis risk.