Assessment of cam morphology of the hip with ultra sound imaging by physical therapists is reliable and valid

Ultrasound Demonstrates Potential in Identify Proximal Femoral Morphology Before and After Cam Resection: A Cadaveric Study

PURPOSE

(1) To compare alpha angles measured on fluoroscopy with those measured on ultrasound pre- and postosteoplasty and (2) to determine whether ultrasound can adequately assess cam deformity correction.

METHODS

Twelve full-body specimens (20 hips) were analyzed. Images using fluoroscopy and ultrasound were captured of the operative hip with the hip in 6 consistent positions: 3 views in hip extension (neutral [N], 30° internal rotation [IR], and 30° external rotation [ER]) and 3 views in hip flexion of 50° (neutral [F-N], 40° external rotation [F-ER40], and 60° external rotation [F-ER60]). A curved-array ultrasound transducer probe was used with the transducer placed in line with the femoral neck to evaluate the proximal femoral morphology. An open femoral osteoplasty using an anterior approach was performed. Fluoroscopy and ultrasound were again used to capture images with the hip in the same 6 positions. Bland-Altman plots were used to determine whether fluoroscopic and ultrasound alpha angles agreed at each position. Independent t-tests were used to compare the alpha angles between the 2 modalities at each position, and paired t-tests were used to compare preoperative and postoperative alpha angles at each position.

RESULTS

No significant differences between the alpha angle on fluoroscopy and ultrasound at all 6 positions were appreciated preosteoplasty. The mean preoperative alpha angle on ultrasound in each position was as follows: N (55.4° ± 5.9° vs 43.0° ± 2.1°), IR (55.1° ± 5.3° vs 43.9° ± 5.5°), ER (58.6° ± 5.6° vs 42.8° ± 3.0°), F-N (53.9° ± 5.5° vs 41.6° ± 3.3°), F-ER40 (55.5° ± 4.6° vs 41.5° ± 2.7°), and F-ER60 (57.9° ± 6.5° vs 41.2° ± 4.2°). The mean preoperative and postoperative alpha angle on fluoroscopy in each position were as follows: N (56.0 ± 12.8° vs 43.1 ± 2.1°), IR (54.1 ± 13.4° vs 41.9 ± 2.9°), ER (61.2 ± 11.0° vs 44.2 ± 1.9°), F-N (57.9 ± 10.6° vs 44.0 ± 2.3°), F-ER40 (59 ± 8.2° vs 42 ± 2.2°), and F-ER60 (55 ± 7.6° vs 41.1 ± 2.6°). Postosteoplasty, there was no significant difference between the mean alpha angle on fluoroscopy versus ultrasound in any position except F-N (44.0 ± 2.3 vs 41.6 ± 3.3, P = .015). Bland-Altman plots showed a high level of agreement between alpha angle values on fluoroscopy and ultrasound at all positions pre- and postosteoplasty. There was a significant reduction in alpha angle measured on ultrasound and fluoroscopy at each position following osteoplasty. There were no significant differences in the delta of the pre- and postosteoplasty alpha angle measurements between fluoroscopy and ultrasound.

CONCLUSIONS

Ultrasound is a useful tool for assessing a cam deformity in patients with femoroacetabular impingement syndrome and for determining adequate resection of a cam deformity intraoperatively.

CLINICAL RELEVANCE

Due to the inherent limitations and risks of the fluoroscopy, it is worth evaluating other nonionizing imaging modalities. Ultrasound has potential to be an accessible, cost-effective, and safe imaging modality that lacks radiation and is commonly used for intra-articular hip injections and dynamic examination of the hip.

Ultrasound Can Determine Joint Distraction During Hip Arthroscopy but Fluoroscopic-Guided Portal Placement Is Superior

Purpose

To compare joint distraction measured on ultrasound (US) with joint space width (JSW) measured on fluoroscopy in hip arthroscopy and to determine whether ultrasound guidance is as safe and effective as fluoroscopy, the current gold standard, for establishing arthroscopic portals.

Methods

Cadaveric whole-body specimens were positioned supine and subjected to 60 lbs. of unilateral axial traction using a distal femoral Steinman pin. Joint distraction was measured via JSW on fluoroscopic and ultrasound images. A single, fellowship-trained orthopaedic surgeon established anterolateral arthroscopy portals via ultrasound or fluoroscopic guidance in a randomized sequence. Total procedure time, number of times the spinal needle pierced the capsule, and iatrogenic chondral or labral injury were recorded.

Results

Twelve full-body specimens (20 hips) underwent distraction, and 17 hips underwent portal placement with fluoroscopic (n = 8) or ultrasound (n = 9) guidance. JSW measured on ultrasound was significantly less laterally (13.0 vs 9.2 mm, P < .001), apically (16.7 vs 9.2 mm, P < .001), and medially (17.9 vs 9.2 mm, P < .001). Successful portal entry was achieved in every specimen. Average procedure time was 133 ± 51 seconds for the fluoroscopy group and 371 ± 260 seconds for the ultrasound group (P = .026). Fluoroscopic guidance required significantly less needle insertion attempts at 1.13 compared with 3.33 attempts for ultrasound (P = .022). Labral damage was greater in the ultrasound group at 66.67% compared with 12.50% for fluoroscopy (P = .0497).

Conclusions

Joint distraction measured on ultrasound can be used to subjectively determine if the joint is adequately distracted in hip arthroscopy. Ultrasound-guided portal placement was associated with more needle insertion attempts, iatrogenic injury of the labrum, and overall procedure time in comparison to fluoroscopic guidance.

Clinical Relevance

Fluoroscopy is the gold standard to confirm adequate joint distraction, aid in establishing arthroscopy portals, and evaluate resection of the femoral head during hip arthroscopy but exposes the patient to ionizing radiation, requires additional operators in the operating room, and involves the need for a heavy lead shield. Alternatives to fluoroscopy are needed, but ultrasound has not proven superior in our cadaveric model.

The EFSUMB Guidelines and Recommendations for Musculoskeletal Ultrasound - Part II: Joint Pathologies, Pediatric Applications, and Guided Procedures

The second part of the Guidelines and Recommendations for Musculoskeletal Ultrasound (MSUS), produced under the auspices of EFSUMB, following the same methodology as for Part 1, provides information and recommendations on the use of this imaging modality for joint pathology, pediatric applications, and musculoskeletal ultrasound-guided procedures. Clinical application, practical points, limitations, and artifacts are described and discussed for every joint or procedure. The document is intended to guide clinical users in their daily practice.