Effects of repeated squat movements on the results of Craig’s test to determine hip anteversion/retroversion

Abstract

[Purpose] Craig’s Test can be used to measure femoral anteversion/retroversion in lieu of expensive and invasive clinical imaging. It is currently unknown if Craig’s Test is reliable before and after exercises that require substantial active hip joint motion. This study sought to evaluate the consistency of Craig’s Test before and after a squatting exercise. [Participants and Methods] Thirty-eight participants (18 females, 20 males) underwent Craig’s Test before and after a squatting protocol. Craig’s Test was repeated 3 times per leg and averaged to achieve a “pre” and “post” score. Scores were compared for the complete sample, females, and males, on both the right and left legs. [Results] All individual comparisons indicated significant differences between pre- and post-squatting Craig’s Test scores for the combined sample, females, and males, on both the right and left legs. [Conclusion] These data suggest Craig’s Test is sensitive to changes in soft tissue extensibility that accompanies exercises that elicit large active range of motion at the hip joint. Thus, an active warm-up involving movements or stretches requiring large ranges of motion at the hip joint are recommended before performing Craig’s Test to determine hip anteversion/retroversion alignment.

INTRODUCTION

Malalignments in hip anteversion-retroversion have been associated with various pathologies of the lower extremity such as hip osteoarthritis^1,2,3), patellofemoral cartilage degradation⁴⁾, hip impingement^{5, 6)}, and knee osteoarthritis⁷⁾. Anteversion-retroversion of the whole hip joint is a complex combination of rotational alignments of both the acetabulum and proximal femur and is associated with the passive range of motion possible at the hip joint⁸⁾. Therefore, accurately determining the alignment of the hip joints is extremely important in identifying those at risk of developing various lower limb pathologies and developing interventions to prevent and treat these pathologies.

The determination of the anteversion-retroversion alignment of the hip joint is difficult, even when using complex and invasive imaging technologies^{9, 10)}. Determining the alignment of the acetabulum and proximal femur non-invasively is not currently possible; however, Craig’s Test has been commonly used to measure femoral anteversion and has been shown to be a highly reliable test across both trained raters and different days^11,12,13,14). Further, Craig’s Test shows moderate agreement with magnetic resonance imaging for measuring femoral anteversion, with intraclass correlation coefficients of 0.67–0.69¹³⁾. This test is thought to measure the alignment of the bony anatomy, but it is possible that the mobility of the soft tissues around the hip joint (e.g., joint capsule, muscles, etc.) could influence the results of Craig’s Test. It is well known that movement, including stretching and dynamic activity, can increase tissue extensibility¹⁵⁾. However, it is currently unknown what effect the soft tissues around the hip joint have on Craig’s Test; therefore, this study sought to examine the results of Craig’s Test before and after squatting exercises requiring large ranges of motion at the hip joint. We hypothesized that Craig’s Test would indicate greater femoral anteversion following a dynamic squatting exercise.

PARTICIPANTS AND METHODS

Thirty-eight participants volunteered for this study (Table 1). Participants reported being free from lower limb pathologies or having either an injury or a surgical history within the 6 months prior to participating. All study procedures were approved by the University of Arkansas for Medical Sciences (UAMS) Institutional Review Board (IRB # 297864), and all participants read and signed a written informed consent before participating in the study.

Table 1. Participant characteristics.

	All Participants (n=38)	Female (n=18)	Male (n=20)
Age (years)	30.7 ± 5.3	32.4 ± 4.9	29.2 ± 5.2
Height (cm)	174.4 ± 9.7	167.7 ± 6.9	180.4 ± 7.8
Mass (kg)	74.7 ± 15.9	67.4 ± 14.1	81.7 ± 14.7

All values are presented as mean ± SD.

Participants wore tight fitting spandex shorts and shirt for all testing to allow for easy identification of key anatomical landmarks. Two sets of three repetitions of Craig’s Test were done on each leg for each participant by a single, experienced clinician, one set before doing the squat exercises, and one set immediately after. The clinician performing Craig’s Test, an orthopaedic clinical specialist board-certified physical therapist with 6.5 years of clinical experience in outpatient orthopaedic practice, was blinded to the results of each test. The Craig’s Test procedure utilized was modified based on recommendation presented in Choi and Kang¹²⁾. Figure 1 shows the testing procedure. A plumb line, created by hanging a string from the ceiling with a weight tied to the end, was used to identify the vertical orientation of the tibia (string positioned to bisect the patella to the mid-malleolar line) in the starting position (Fig. 1A). While laying prone on a treatment table, the participant’s knee was flexed to 90 degrees and an instrumented digital inclinometer (Lafayette, IN, USA) was placed on the lateral malleolus was then zeroed in this position by a second clinical research assistant, a physical therapist with 1.5 years of clinical experience in outpatient orthopaedic practice. The tibia was then rotated until the most prominent position of the greater trochanter was palpated by the first clinician that performed the Craig’s Tests. The difference of angle from the initial vertical position was noted by a separate research assistant (Fig. 1B).

Fig. 1.

Craig’s Test experimental procedures modified from Choi and Kang¹²⁾. (A) Shows the set-up position with the participant’s tibia aligned with a plumb line hung from the ceiling. (B) Shows measurement of the difference between starting position using digital inclinometer.

Following the initial set of Craig’s Tests, participants performed 6 sets of squats (22 total squats) with heels raised on a 5 cm high block where they were asked to squat “as low as they could comfortably control” on every repetition: (1) 5 bilateral squats with the feet pointed straight ahead, (2) 5 bilateral squats with the feet toed out, (3) 3 single leg squats on the right leg with the foot positioned straight, (4) 3 single leg squats on the left leg with the foot toed out, (5) 3 single leg squats with the foot positioned straight, (6) 3 single leg squats on the left leg with the foot toed out. The order of the squats was randomized, and volitional rest was provided between sets. Craig’s Test was then repeated after these squats and the removal of the motion tracking markers.

The three trials on each leg were averaged together to give one Craig’s Test score for each leg both before and after squatting. SPSS software v31 was used to perform six paired sample t-tests on the right and left legs separately, for males, females, and the combined sample, to compare before and after squatting with a significance level of p<0.05.

RESULTS

Average Craig’s Test results are reported in Table 2. In all comparisons, Craig’s Test results indicated greater anteversion angles after the squatting exercise compared the results before squatting (all participants: left leg: p<0.001, right leg p<0.001). For males, 12/20 (60%) participants demonstrated greater anteversion of the left leg after squatting, and 13/20 (65%) demonstrated greater anteversion of the right leg after squatting (p=0.040 and p=0.019, respectively). For female participants, 15/18 (83%) for the left leg and 14/18 (78%) for the right leg demonstrated greater anteversion via increased Craig’s Test scores after squatting (p<0.001 and p=0.001, respectively). Figure 2 shows the pre-post measurements for all participants.

Table 2. Craig’s test results pre-squat and post-squat for the right and left leg.

	Right Leg			Left Leg
	Pre-squat	Post-squat	Sig.	Pre-squat	Post-squat	Sig.
All Participants (n=38)	23.1 ± 9.3	25.4 ± 9.9	*	21.9 ± 8.2	24.3 ± 9.2	*
Male (n=20)	18.3 ± 5.4	19.9 ± 6.7	*	17.6 ± 6.2	19.0 ± 6.1	*
Female (n=18)	28.4 ± 9.9	31.5 ± 9.4	*	26.7 ± 7.5	30.1 ± 8.5	*

All values are presented in degrees (^o) as mean ± SD. *=significance difference between pre-squat and post-squat (p<0.05). Sig.: significance.

Fig. 2.

Craig’s Test Scores for the left and right leg before and after the squatting protocol for all participants.

DISCUSSION

This study examined the Craig’s Test before and after squatting exercises requiring large ranges of motion at the hip joint. Consistent with our hypothesis, we measured greater femoral anteversion angles, via Craig’s Test, on both limbs following the squatting exercises. These findings suggest any tightness in soft tissues around the hip joint can potentially alter the results of Craig’s Test in determining femoral anteversions/retroversion. It has previously been reported that Craig’s Test is a measure of bony structure/alignment of the femur/hip joint¹⁶⁾; however, the current findings indicate there may be other factors at play in the results of this clinical test.

Hip rotational restrictions are relatively common in various athletic populations^17,18,19) and are thought to result from anatomical restrictions and/or tightness in the soft tissues (e.g., musculature, capsule, ligaments) surrounding the hip joint. In line with the sensory theory of muscle extensibility²⁰⁾, it can be hypothesized that performing several squats requiring a large active range of motion at the hip, could stretch these soft tissues, resulting in altered Craig’s Test results in the majority of study participants after the squatting movements. Indeed, previous investigations have reported increased joint range of motion after a single bout of stretching, perhaps due to enhanced sensory perceptions^{21, 22)}. Since all the participants in this study were healthy and had no musculoskeletal pain, we hypothesize that any restrictions these individuals may have had in their hip would most likely be related to tightness in the soft tissues and not severe anatomical abnormalities.

Although this study focused on changes in Craig’s Test measurements pre- and post-squatting, the findings are limited by the homogenous population of healthy young adults. An additional limitation of this study is that the pelvis was not stabilized externally during Craig’s Test and we did not use a goniometer to confirm the knee was flexed to 90 degrees throughout the test. Future studies should include larger samples with additional age groups and populations and consider stratifying participants based on their femoral alignment. Investigations including comparisons to clinical imaging before and after activity and establishing a minimal clinically important difference would help strengthen the clinical utility of Craig’s Test.

A strength of this study is that a single rater completed all Craig’s Tests, thereby reducing the likelihood of inter-rater inconsistencies. Further, our single, trained rater’s perception of endpoint resistance during the Craig’s Test was likely influenced by the aforementioned tissue extensibility. Therefore, based on these data, we recommend some form of warm-up involving movements requiring large ranges of motion at the hip joint before performing Craig’s Test to determine hip anteversion/retroversion alignment.

Funding and Conflict of interest

None.