Decreased femoral head-neck offset: a possible risk factor for ACL injury

Radiographic Cam Morphology of the Hip May Be Associated with ACL Injury of the Knee: A Case-Control Study

Purpose

To evaluate femoral and acetabular morphology in patients who underwent anterior cruciate ligament reconstruction (ACLR).

Methods

A retrospective review of a prospectively collected ACL registry was performed to identify patients with pelvis radiographs before undergoing either primary or revision ACLR between January 2010 and August 2020. Alpha angle (AA), head-neck offset ratio (HNOR), lateral center edge angle (LCEA), and crossover sign (COS) were measured on the operative side. Values were compared to a negative control group that did not significantly differ in age, sex, or body mass index. Univariate analysis and Pearson’s correlation coefficient were used to compare groups with significance defined as P < .05.

Results

In total, 114 patients were included (ACL, n = 38; control, n = 76). Eleven primary and 27 revision ACL reconstructions were identified. The mean AA in patients undergoing primary ACL reconstruction was higher than control (67.45° ± 11.30° vs 51.5° ± 10.8°, P < .001). A significantly elevated AA was also found in those undergoing revision ACL surgery (61.8° ± 7.51° vs 51.5° ± 10.8°, P < .001). In addition, the HNOR was significantly lower in the ACL group (0.12 ± 0.03 vs 0.14 ± 0.04, P = .0304). Acetabular morphology was similar between groups (LCEA, ACL 31.97° ± 5.04° vs control 30.01° ± 5.17°, P = .0549; COS, ACL 9 of 38 (23.7%) vs control 18 of 76 (23.7%), P = 1.00).

Conclusion

An association exists between radiographic cam morphology of the hip and patients who previously underwent ACLR.

Level of Evidence

III, retrospective comparison study.

Is restricted hip movement a risk factor for anterior cruciate ligament injury?

Restricted hip movement along with femoroacetabular impingement (FAI) has been reported to be an important risk factor in anterior cruciate ligament (ACL) injury. We performed a literature review assessing the evidence that FAI, or restricted hip movement, contributes to the likelihood of sustaining an ACL injury to provide an evidence-based and comprehensive update on the relationship between these pathologies. Studies were divided into three categories: clinical studies, radiological studies and cadaveric studies. Clinical studies primarily assessed the limitations to hip movement in patients with ACL injury, and numerous studies of this kind have demonstrated a relationship between restricted movement and ACL injury. Radiological studies have been able to demonstrate a higher number of bony hip abnormalities in patients with ACL injury. However, due to variable results within these studies, it is unclear which kinds of bony abnormality are specifically associated with an increased risk of ACL injury. Cadaveric studies have demonstrated that peak ACL relative strain was inversely related to the range of internal rotation of the femur, thus providing a potential mechanism for this relationship. In conclusion, clinical and radiological studies have established a correlation between restricted hip and ACL injury, but have been unable to demonstrate an increased risk of future ACL injury in individuals with restricted hip movement. Future prospective cohort studies are necessary to confirm this. Additionally, these findings highlight the need for a thorough clinical assessment of the hip when assessing patients with an ACL injury.

Effect of prior ipsilateral lower extremity surgery on 2-year outcomes following hip arthroscopy for femoroacetabular impingement syndrome

The purpose of this study was to determine the influence of prior lower extremity surgery on patient reported outcomes following hip arthroscopy for femoroacetabular impingement syndrome (FAIS). Consecutive patients who underwent hip arthroscopy for FAIS and a prior history of ipsilateral lower extremity surgery were identified and matched 2:1 by age, gender, and body mass index (BMI) to controls without a history of lower extremity surgery. The minimal clinically important difference (MCID) and patient acceptable symptomatic state (PASS) were calculated for HOS–ADL, HOS–SS, and mHHS. Preoperative and 2-year postoperative patient reported outcomes of both groups were compared, and logistic regression was performed to determine whether lower extremity surgery influenced achieving MCID and PASS. A total of 102 patients (24.94%) with prior history of ipsilateral lower extremity surgery were identified. Ipsilateral orthopaedic knee surgery accounted for more than half (53.92%) of all prior surgeries. Patients with a history of ipsilateral lower extremity surgery had significant lower 2-year PROs, satisfaction, and greater pain when compared to patients without lower extremity surgery (P < 0.001 all). A history of ipsilateral lower extremity surgery was a negative predictor of achieving MCID for HOS–ADL and HOS–SS, as well as PASS for HOS–ADL, HOS–SS, and mHHS (P < 0.001 all).

In conclusion, patients with prior lower extremity surgery were found to have inferior outcome scores and a lower likelihood of achieving clinically significant outcome improvement compared to patients without a history of lower extremity surgery at two years postoperatively.

Is There an Association Between Noncontact Anterior Cruciate Ligament Injuries and Decreased Hip Internal Rotation or Radiographic Femoroacetabular Impingement? A Systematic Review

PURPOSE

To perform a systematic review to determine if there is (1) an association between decreased hip internal rotation and anterior cruciate ligament (ACL) tear rates; (2) an association between radiographic femoroacetabular impingement (FAI) and ACL tear rates; and (3) biomechanical evidence demonstrating increased strain in the ACL of patients with decreased hip internal rotation.

METHODS

A systematic review was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies investigating relationships between hip motion, hip radiographs, and ACL tear were sought. Studies with Levels of evidence I-IV were eligible for inclusion. Study methodology/evidence were evaluated using Methodological Index for Non-Randomized Studies (MINORS), Strengthening the Reporting of Observational Studies in Epidemiology (STROBE), and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria.

RESULTS

Eleven studies were analyzed (2 cadaveric in vitro models, 8 clinical studies measuring hip internal rotation (2 concurrently assessing radiographic FAI), and 1 clinical study assessing radiographic FAI alone). Mean MINORS, STROBE, and GRADE for the studies was 82.4%, 20.9 out of 22, and "low," respectively. A total of 959 subjects (84.8% male; mean age 23.6 ± 3.8 years) were analyzed. Overall, 378 subjects sustained 427 ACL tears (399 primary ACL ruptures, 28 reruptures). Six of 8 clinical studies identified a significant association between limited rotation (internal rotation [IR; loss greater than 10°-20°], external rotation [ER], or combined IR + ER [loss greater than 20°]) and ACL tears. Two studies found an association between ACL ruptures and radiographic cam/pincer impingement. Two cadaveric models found a significant association between ACL strain and limited hip internal rotation.

CONCLUSIONS

This systematic review identified a significant association between ACL tear and both limited hip rotation and radiographic FAI.

LEVEL OF EVIDENCE

Level IV, systematic review of Levels II-IV studies.

Diminished femoral head-neck offset and the restricted hip range of motion suggesting a possible role in ACL injuries

PURPOSE

Femoroacetabular impingement may be associated with anterior cruciate ligament (ACL) injuries. The purpose of this study was to determine the head-neck offset, as measured by 45° Dunn's view alpha angles, in patients with ACL injuries compared to control subjects.

METHODS

In this retrospective study, 140 consecutive non-professional athletes with primary ACL ruptures confirmed with knee arthroscopy and 100 consecutive patients with non-ACL injury were enrolled. Hip range of motion was assessed in lower extremities in all participants, and alpha angle was calculated according to 45° Dunn's view radiographs.

RESULTS

There is not any difference in age, gender distribution, height, weight, and BMI between groups. Internal rotation, abduction, and adduction of the hip were significantly decreased in ACL-injured patients comparing with control subjects (p < 0.001). ACL-injured patients had also a significantly higher alpha angle comparing to the control individuals (p < 0.001). The mean of alpha angle in the ACL-injured patients was 56.1 (SD 10.1) and in the non-ACL-injured group was 49.3 (SD 9.4).

CONCLUSIONS

The patients in ACL-injured group showed a significant restriction in hip range of motion and also a diminished femoral head-neck offset suggesting a possible role of these findings in the outcome assessed.

LEVEL OF EVIDENCE

III.

Does decrease in hip range of motion interfere in frontal plane leg alignment in teenage soccer players?

INTRODUCTION

This study determines cross-sectional changes in transverse plane hip range of motion (ROM) in teenager soccer athletes and non-athletes and correlates these measures with changes in frontal plane leg alignment (varus-valgus alignment).

EVIDENCE ACQUISITION

This was a comparative cross-sectional study with non-random convenience sampling.

EVIDENCE SYNTHESIS

Participants were recruited from a major professional soccer club and two local state-run schools in southern Brazil. A total of 396 male participants aged 9-18 years were assessed, 183 soccer players (athlete group; mean age, 13.3 ± 2.7 years) and 213 students (non-athlete group; mean age 14.4 ± 2.5 years). Hip internal rotation (IR) and external rotation (ER) and frontal plane leg alignment were measured in all participants. Changes in transverse plane hip ROM and frontal plane leg alignment were determined. Mean IR was 20.7° ± 5.8° in athletes versus 32.8° ± 2.9° in non-athletes, and mean ER was 36.5° ± 7.4° in athletes versus 46.7° ± 4.8° in non-athletes. Overall, IR was decreased in the athlete group compared to the non-athlete group (P < 0.001). Mean IR and ER were significantly lower in older athletes (P < 0.001), while only ER was significantly lower in older non-athletes (P < 0.001). Varus leg alignment was prevalent at all ages in the athlete group (71.0%, P = 0.153). In the non-athlete group, the occurrence of varus leg alignment was higher in older participants (P = 0.001). Lower mean IR was correlated with more severe varus leg alignment in the athlete group (rs = 0.19; P = 0.009).

CONCLUSIONS

We found a lower hip ROM, particularly in IR, in teenager soccer players according to the enhancement age group from the sample. But varus alignment of the leg was also prevalent in this group and comes before hip abnormalities started to be detected.

Assessment of the alpha angle and mobility of the hip in patients with noncontact anterior cruciate ligament injury

PURPOSE

To evaluate the alpha angle of the hip in patients with noncontact anterior cruciate ligament (ACL) injury and compare it with patients without injury. In addition, external and internal rotation of the hip was assessed and correlated with the alpha angle.

METHODS

The alpha angle of the ipsilateral hip was assessed in 41 subjects with non-contact ACL tear and compared with 39 subjects with no tear. The external and internal rotation of the ipsilateral hip was also evaluated.

RESULTS

The alpha angle was larger in subjects with noncontact ACL injury. The mean was 70.31° (±13.92°) compared with 58.55° (±13.95°) in the control group (p < 0.001). The groups were similar when considering the external, internal, and sum of rotation of the ipsilateral hip. There was no correlation between the alpha angle and decreased rotational range of motion of the hip in either group (p > 0.05).

CONCLUSION

Patients with noncontact ACL injury presented a greater alpha angle when compared with the group without tear. There was no difference in the rotational mobility of the hip between groups, nor was there a correlation between the increase in the alpha angle and the decrease in the rotational mobility of the hip.

Editorial Commentary: The Hip Bone's Connected to the Knee Bone, but Correlation Does Not Equal Causation-The Association of Hip Motion, Femoroacetabular Impingement, and Anterior Cruciate Ligament Injury

Patients with anterior cruciate ligament (ACL) injury had significantly less hip rotational motion (internal rotation [IR] and sum of IR and external rotation) than control subjects without ACL tears. For each hip IR increase of 10°, the odds of sustaining an ACL rupture decreased by a factor of 0.419. Although this investigation does not prove (causation) that loss of hip rotational motion causes an ACL tear, it does continue to complement the growing and evolving literature base showing an upstream or downstream association (correlation) of decreased hip motion on adjacent structures.

Restricted Hip Rotation Is Correlated With an Increased Risk for Anterior Cruciate Ligament Injury

PURPOSE

The primary purpose was to compare ipsilateral hip internal rotation (IR) in male and female athletes with or without an anterior cruciate ligament (ACL) tear. A secondary purpose was to compare radiographic markers of femoroacetabular impingement (FAI) in patients with or without an ACL tear.

METHODS

In this prospective case-control study, based on a power analysis, a convenience sample of 25 ACL-injured and 25 control patients matched by age and gender were examined over 14 months. The ACL injury group included preoperative patients 12-40 years old with an ACL rupture within the previous 3 months with no prior lower extremity injuries, ligamentous laxity, or arthralgias. Controls included patients presenting with an upper extremity complaint with no history of knee injury. In the outpatient clinic, hip axial rotation range of motion was measured with a goniometer on physical examination and hip radiographs were evaluated for morphologic variations consistent with FAI. Univariate analysis of variance was used to examine differences between groups.

RESULTS

Each group had 13 males and 12 females, average ages of 22.8 ± 7.2 years (ACL group) versus 24.5 ± 7.9 years (controls; P = .439). The average sum of hip rotation (internal plus external) in patients with an ACL tear was 60.3 ± 12.4° compared with 72.6 ± 17.2° in controls (P = .006). ACL-injured patients had decreased hip IR compared with controls, with respective mean measurements of 23.4 ± 7.6° versus 30.4 ± 10.4° (P = .009). For every 10° increase in hip IR, the odds of having an ACL tear decreased by a factor of 0.419 (P = .015).

CONCLUSIONS

Risk of ACL injury is associated with restricted hip IR, and as hip IR increases, the odds of having an ACL tear decreases. In addition, ACL injury is associated with FAI in a generalized population of male and female athletes, although causality cannot be determined and most ACL-injured patients do not exhibit hip complaints.

LEVEL OF EVIDENCE

Level II, prognostic, prospective cohort study.

Range of motion and radiographic analysis of the hip in patients with contact and non-contact anterior cruciate ligament injury

PURPOSE

To compare the range of motion (ROM) and radiography of the hip joints in male patients with contact anterior cruciate ligament (ACL) injury and non-contact ACL injury.

METHODS

ROM of the ipsilateral hip was evaluated in 35 male patients with contact ACL injury (contact group) and compared to that of 45 male patients with a non-contact ACL injury (non-contact group). Radiographic evaluation of hip joints was also performed to assess the presence of cam and pincer-type deformity .

RESULTS

ROM of the hip joint was statistically higher in patients with contact ACL injury. The average sum of hip rotation in the non-contact group was 66.1 ± 8.4° compared to 79.4 ± 10.6° for the contact group (p < 0.001). Seventy-seven per cent of patients in the non-contact group had a sum of hip rotation <70° and 93 % had <80°, compared to17.1 and 42.9 % in the contact group (p < 0.001). Prevalence of cam or pincer deformity was similar in the groups. Cam or pincer deformity was not more frequent in patients with limited ROM of the hip.

CONCLUSION

Individuals with contact ACL injury had greater ROM of the hip joints than those with non-contact ACL injury. The presence of cam or pincer deformity was similar in both groups and was not related to decreased ROM of the hip joints. These findings may assist the surgeons to identify new risk factors for non-contact ACL injury and, additionally, develop prevention program of injury.

LEVEL OF EVIDENCE

III.

Abnormal hip physical examination findings in asymptomatic female soccer athletes

PURPOSE

Examination of the hip provides information regarding risk for pre-arthritic hip disorders, knee injuries, and low back pain. The purpose of this study was to report a hip screening examination of asymptomatic female soccer athletes and to test the hypothesis that these findings vary by competition experience.

METHODS

Asymptomatic females from a youth soccer club, a college, and a professional team were evaluated. Passive hip range of motion, hip abduction strength, and hip provocative tests were assessed. Data were compared for the grade/middle school, high school, college, and professional athletes.

RESULTS

One hundred and seventy-two athletes with a mean age of 16.7 ± 5 years (range 10-30) participated. Professional athletes had less flexion (HF) for both hips (p < 0.0001) and less internal rotation (IR) for the preferred kicking leg (p < 0.05) compared to all other groups. Grade/middle school athletes had more external rotation in both hips as compared to all other groups (p < 0.0001). For the preferred kicking leg, collegiate athletes had less hip abduction strength as compared to other groups (p < 0.01). Positive provocative hip tests were found in 22 % of all players and 36 % of the professionals. In professionals, a positive provocative test was associated with ipsilateral decreased HF (p = 0.04).

CONCLUSION

Asymptomatic elite female soccer athletes with the most competition experience had less bilateral hip flexion and preferred kicking leg IR than less-experienced athletes. Positive provocative hip tests were found in 22 % of athletes. Future studies are needed to show whether these findings link to risk for intra-articular hip or lumbar spine and knee disorders.

LEVEL OF EVIDENCE

III.

Does limited internal femoral rotation increase peak anterior cruciate ligament strain during a simulated pivot landing?

BACKGROUND

Many factors contributing to anterior cruciate ligament (ACL) injury risk have been investigated. Recently, some ACL-injured individuals have presented with a decreased range of hip internal rotation compared with controls. The pathomechanics of why decreased hip range of motion increases risk of ACL injury have not yet been studied.

HYPOTHESIS

Peak relative strain of the anteromedial bundle of the ACL (AM-ACL) during a simulated single-leg pivot landing is inversely related to the available range of internal femoral rotation.

STUDY DESIGN

Controlled laboratory study.

METHODS

A series of pivot landings were simulated in 10 female and 10 male human knee specimens with a testing apparatus that applied a 2-bodyweight impulsive load, inducing knee compression, flexion moment, and internal tibial torque. The range of internal femoral rotation was (1) locked at ~0°, (2) limited with a hard stop to ~7°, (3) limited with a hard stop to ~11°, or (4) free, with rotation resisted by 2 springs to simulate the resistance of the active hip rotator muscles to stretch. The AM-ACL strain was quantified with a differential variable reluctance transducer. A linear mixed model was used to determine whether a significant linear relation existed between peak AM-ACL relative strain and range of internal femoral rotation.

RESULTS

Peak AM-ACL relative strain was inversely related to the available range of internal femoral rotation (R (2) = 0.91; P < .001), with strain increasing 1.3% for every 10° decrease in rotation; this represented a 20% increase in peak relative strain, given an average range of femoral rotation of 15° upon landing in healthy athletes.

CONCLUSION

Peak AM-ACL relative strain was inversely proportional to the available range of internal femoral rotation during simulated single-leg pivot landings.

CLINICAL RELEVANCE

Decreased range of internal femoral rotation results in greater ACL strain and may therefore increase the susceptibility to ACL rupture with athletic cutting and pivoting activities. Screening for a limited range of hip internal rotation should therefore become a component of not only ACL injury prevention programs but also evaluation protocols for those with ACL injuries and/or reconstructions.

Prevention of anterior cruciate ligament injuries in sports. Part I: systematic review of risk factors in male athletes

PURPOSE

The purpose of this study was to report a comprehensive literature review on the risk factors for anterior cruciate ligament (ACL) injuries in male athletes.

METHODS

All abstracts were read and articles of potential interest were reviewed in detail to determine on inclusion status for systematic review. Information regarding risk factors for ACL injuries in male athletes was extracted from all included studies in systematic fashion and classified as environmental, anatomical, hormonal, neuromuscular, or biomechanical. Data extraction involved general characteristics of the included studies (type of study, characteristics of the sample, type of sport), methodological aspects (for quality assessment), and the principal results for each type of risk factor.

RESULTS

The principal findings of this systematic review related to the risk factors for ACL injury in male athletes are: (1) most of the evidence is related to environmental and anatomical risk factors; (2) dry weather conditions may increase the risk of non-contact ACL injuries in male athletes; (3) artificial turf may increase the risk of non-contact ACL injuries in male athletes; (4) higher posterior tibial slope of the lateral tibial plateau may increase the risk of non-contact ACL injuries in male athletes.

CONCLUSION

Anterior cruciate ligament injury in male athletes likely has a multi-factorial aetiology. There is a lack of evidence regarding neuromuscular and biomechanical risk factors for ACL injury in male athletes. Future research in male populations is warranted to provide adequate prevention strategies aimed to decrease the risk of this serious injury in these populations.

Association between Femoral Anteversion and Lower Extremity Posture upon Single-leg Landing: Implications for Anterior Cruciate Ligament Injury

[Purpose] Increased femoral anteversion may occur with hip internal rotation and valgus knee alignment upon landing and is considered a risk factor for anterior cruciate ligament injury. We examined the relationship between femoral anteversion and joint motion and muscle activity of the lower extremity in terms of the risk factors for anterior cruciate ligament injury. [Subjects] Sixteen healthy females were divided on the basis of femoral anteversion into low and high groups. [Methods] Femoral anteversion was assessed using Craig's test. We performed kinematic analysis and measured the electromyography activity of the lower extremity upon left single-leg landing. [Results] The high group had a significantly lower hip flexion angle and higher knee flexion and valgus angles than the low group. The rectus femoris showed significantly greater electromyography activities in the high group than in the low group. [Conclusion] These results suggest that increased femoral anteversion results in lower hip flexion angle, higher knee valgus alignment, and greater rectus femoris muscle activity, leading to anterior tibial displacement upon single-leg landing. Increased femoral anteversion may be a potential risk factor for anterior cruciate ligament injury.