A new pelvic tilt detection device: roentgenographic validation and application to assessment of hip motion in professional ice hockey players

A Sensor-Based Screening Tool for Identifying High Pelvic Mobility in Patients Due to Undergo Total Hip Arthroplasty

There is increasing evidence that pelvic mobility is a critical factor to consider in implant alignment during total hip arthroplasty (THA). Here, we test the feasibility of using an inertial sensor fitted across the sacrum to measure change in pelvic tilt, and hence screen for patients with high pelvic mobility. Patients (n = 32, mean age: 57.4 years) due to receive THA surgery participated in the study. Measures of pelvic tilt were captured simultaneously using the device and radiograph in three functional positions: Standing, flexed-seated, and step-up. We found a strong correlation between the device and radiograph measures for the change in pelvic tilt measure from standing to flexed-seated position (R² = 0.911); 75% of absolute errors were under 5 degrees. We demonstrated that the device can be used as a screening tool to rapidly identify patients who would benefit from more detailed surgical planning of implant positioning to reduce future risks of impingement and dislocation.

Hip biomechanics

As the primary link between the trunk and the lower limb, the hip joint plays an important role in the generation and transmission of forces during routine activities of daily living and athletic activities alike. This joint is characterized by an extraordinary amount of inherent bony stability, with differences in osseous anatomy significantly impacting the biomechanical properties of the human hip. These biomechanical principles have important implications relative to the diagnosis and surgical treatment of structural hip abnormalities, and the physical demands placed on the hip joint during athletic activities may predispose to injury or other chronic pathologic processes.

Reliability limits of the modified Thomas test for assessing rectus femoris muscle flexibility about the knee joint

CONTEXT

The modified Thomas test is commonly used in the clinical setting to assess flexibility about the thigh region.

OBJECTIVE

To evaluate the clinical reliability of the modified Thomas test for evaluating the flexibility of the rectus femoris muscle about the knee joint.

DESIGN

Descriptive laboratory study using a test-retest design.

SETTING

Institution-based clinical orthopaedic setting.

PATIENTS OR OTHER PARTICIPANTS

Fifty-seven individuals between the ages of 18 and 45 years with no history of trauma participated. Of those, 54 completed the study.

INTERVENTION(S)

Three Board-certified athletic therapists with an average of 12.67 years of sport medicine expertise assessed rectus femoris flexibility using pass/fail and goniometer scoring systems. A retest session was completed 7 to 10 days later.

MAIN OUTCOME MEASURE(S)

Parametric and nonparametric tests were used to compare participants' test-retest results.

RESULTS

Chance-corrected kappa values (intrarater x = 0.40, 95% confidence interval [CI] = 0.30, 0.54; interrater x = 0.33, 95% CI = 0.23, 0.41) indicated generally poor levels of reliability for pass/fail scoring. Intraclass correlation coefficient (ICC) values (intrarater x = 0.67, 95% CI = 0.55, 0.76; interrater x = 0.50, 95% CI = 0.40, 0.60) indicated fair to moderate levels of reliability for goniometer data. Measurement error values (standard error of measurement = 7 degrees , method error = 6 degrees , and coefficient of variation = 13%) and Bland-Altman plots (with 95% limits of agreement) further demonstrated the degree of intrarater variance for each examiner when conducting the test.

CONCLUSIONS

These results call into question the statistical reliability of the modified Thomas test and provide clinicians with important information regarding its reliability limits when used to clinically assess flexibility of the rectus femoris muscle about the knee joint in a physically active population. More research is needed to ascertain the variables that may confound the statistical reliability of this orthopaedic technique.

A new tilt on pelvic radiographs: a pilot study

AIM

The aim of this study was to evaluate pelvic tilt on commonly performed measurements on radiography in primary protrusio acetabuli and developmental dysplasia of the hip.

MATERIALS AND METHODS

A dry assembled pelvis and spine skeleton was positioned in an isocentric skull unit and films exposed with increasing degrees of angulation of pelvic tilt. The films were then read by two independent readers for seven different measurements used to evaluate the hips and acetabular: acetabular line to ilioischial line, teardrop appearance, intercristal/intertuberous ratio, co-ordinates of femoral head, centre edge angle, acetabular depth/width ratio and acetabular angle.

RESULTS

There was so much variation in the protrusio results that no formal recommendation of any standard radiographic test can be given. Only the inter tuberous distance is not effected by pelvic tilt. The acetabular angles for developmental dysplasia of the hip showed the most potential with pelvic tilt below 15 degrees.

CONCLUSION

As pelvic tilt increases, measurements used in protusio become unreliable, and computed tomography/magnetic resonance imaging are probably going to be more accurate as one can directly visualise pelvic intrusion. We recommend a lateral view to assess the degree of pelvic tilt in patients with protrusion to ensure these measurements are valid.

Dynamic trunk stabilization: a conceptual back injury prevention program for volleyball athletes

The sport of volleyball creates considerable dynamic trunk stability demands. Back injury occurs all too frequently in volleyball, particularly among female athletes. The purpose of this clinical commentary is to review functional anatomy, muscle coactivation strategies, assessment of trunk muscle performance, and the characteristics of effective exercises for the trunk or core. From this information, a conceptual progressive 3-phase volleyball-specific training program is presented to improve dynamic trunk stability and to potentially reduce the incidence of back injury among volleyball athletes. Phase 1 addresses low-velocity motor control, kinesthetic awareness, and endurance, with the clinician providing cues to teach achievement of biomechanically neutral spine alignment. Phase 2 focuses on progressively higher velocity dynamic multiplanar endurance, coordination, and strength-power challenges integrating upper and lower extremity movements, while maintaining neutral spine alignment. Phase 3 integrates volleyball-specific skill simulations by breaking down composite movement patterns into their component parts, with differing dynamic trunk stability requirements, while maintaining neutral spine alignment. Prospective research is needed to validate the efficacy of this program.

Pelvifemoral rhythm during unilateral hip flexion in standing

OBJECTIVE

To quantify pelvifemoral rhythm during unilateral hip flexion in standing subjects, under different degrees of resistance.

DESIGN

Descriptive and correlational.

BACKGROUND

Pelvic rotation contributes to the change in hip flexion angle while individuals are supine. Degree of contribution in standing has not been described.

METHODS

Pelvic and femoral motions, relative to vertical, were documented while 14 subjects performed three trials of standing unilateral hip flexion, both with and without a 4.53 kg ankle weight. Pelvic and thigh segments were marked with reflective spheres, and motion was captured by video analysis.

RESULTS

Pelvic rotation contributed 18.1% of the change in hip flexion angle. Pelvic rotation occurred throughout the movement. Neither presence of external resistance nor direction of movement significantly changed this contribution.

CONCLUSIONS

A strong relationship exists between pelvic rotation and hip flexion in standing subjects.

RELEVANCE

Hip flexion, while standing, is a common element of many functional activities. Knowledge of the pelvic contribution increases our understanding of hip and lumbar spine motion during standing activities.

Hip and groin injuries in athletes

Although athletic injuries about the hip and groin occur less commonly than injuries in the extremities, they can result in extensive rehabilitation time. Thus, an accurate diagnosis and well-organized treatment plan are critical. Because loads of up to eight times body weight have been demonstrated in the hip joint during jogging, presumably even greater loads can occur during vigorous athletic competition. The available imaging modalities are effective diagnostic tools when selected on the basis of a thorough history and physical examination. Considerable controversy exists as to the cause and optimal treatment of groin pain in athletes, or the so-called "sports hernia." There has also been significant recent attention focused on intraarticular lesions that may be amenable to hip arthroscopy. This article briefly reviews several common hip and groin conditions affecting athletic patients and highlights some newer topics.

The association of hip strength and flexibility with the incidence of adductor muscle strains in professional ice hockey players

This prospective study was conducted to determine whether hip muscle strength and flexibility play a role in the incidence of adductor and hip flexor strains in National Hockey League ice hockey team players. Hip flexion, abduction, and adduction strength were measured in 81 players before two consecutive seasons. Thirty-four players were cut, traded, or sent to the minor league before the beginning of the season. Injury and individual exposure data were recorded for the remaining 47 players. Eight players experienced 11 adductor muscle strains, and there were 4 hip flexor strains. Preseason hip adduction strength was 18% lower in the players who subsequently sustained an adductor muscle strain compared with that of uninjured players. Adduction strength was 95% of abduction strength in the uninjured players but only 78% of abduction strength in the injured players. Preseason hip adductor flexibility was not different between players who sustained adductor muscle strains and those who did not. These results indicate that preseason hip strength testing of professional ice hockey players can identify players at risk of developing adductor muscle strains. A player was 17 times more likely to sustain an adductor muscle strain if his adductor strength was less than 80% of his abductor strength.