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Subspine Hip Impingement: An Unusual Cause of Hip Pain in an Elite Weightlifter

Nabhan, Dustin C. DC; Moreau, William J. DC; McNamara, Shannen C. BS; Briggs, Karen K. MPH; Philippon, Marc J. MD

doi: 10.1249/JSR.0000000000000291
Extremity and Joint Conditions: Case Report

Anterior hip pain can be difficult to diagnose due to the many pathologies and overlapping pain patterns that exist in the hip region. Clinical findings of pain at the anterior inferior iliac spine with passive hip flexion, proximal quadriceps pain and weakness, and painful impingement tests of the hip may be indicative of subspine hip impingement. This report describes the diagnosis and treatment of anterior hip pain, including subspine impingement and femoroacetabular impingement in an elite weightlifter. This case also describes how with the correct diagnosis and treatment, the athlete returned to play to her previous level of sport 11 months after a complex hip injury.

1Clinical Research and Multidisciplinary Care, United States Olympic Committee, Colorado Springs, CO; 2Sports Medicine, United States Olympic Committee, Colorado Springs, CO; 3Center for Outcomes-Based Orthopaedic Research, Steadman Philippon Research Institute, Vail, CO

Address for correspondence: Karen K. Briggs, MPH, Steadman Philippon Research Institute, Vail, CO; E-mail: karen.briggs@sprivail.org.

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Introduction

The evaluation of anterior hip pain can be a diagnostic dilemma for the sports medicine clinician. Patients with femoroacetabular impingement (FAI) and labral tears often take greater than 2 yr, visits to four health care providers, try three types of treatment, and spend approximately $2,500.00 before an accurate diagnosis is made (10). Although advances in diagnostic imaging, arthroscopy, and clinical education have added to the toolbox of the sports medicine physician, the complex regional anatomy and pain referral patterns to the hip can be challenging to navigate (4,6,16,22). Diagnosis of hip pathology can be especially challenging because both intraarticular and extraarticular pathologies may be involved (1,6,16,19,22).

Subspine impingement (SSI), also called anterior-inferior iliac spine (AIIS) impingement is an extraarticular impingement of the femoral neck with a hypertrophic AIIS (3,7,8,11,13,15,18,21). Extreme or repetitive hip flexion results in impingement of the soft tissues of the anterior hip, commonly the deep fibers of the direct head of the rectus femoris tendon, the anterior joint capsule, and the anterior acetabular labrum. Hypertrophy of the AIIS has been described secondary to chronic avulsion injury of the rectus femoris tendon or developmental AIIS prominence (8,11). It is common for patients to have a combination of cam and pincer FAI and AIIS hypertrophy (8,17).

Patients with SSI present clinically with painful and often limited active and passive hip flexion (11,15). The patient may attempt to abduct and externally rotate the hip during hip flexion to avoid contacting the femoral neck to the AIIS, because limited hip internal rotation can occur secondary to variants in AIIS anatomy (9). The patient may describe a history of hip flexor or quadriceps-related pathology, including previous avulsion injury of the quadriceps (8,11).

This report describes the clinical decision-making process and treatment of an elite athlete with SSI resulting from a partial avulsion of the direct head of the rectus femoris with a concurrent linear tear of the acetabular labrum. The purpose of this case report is to describe different pathologies that can be related to anterior hip pain and to demonstrate how effective diagnosis and treatment can allow an elite athlete to return to sport and prior performance level.

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Case Presentation

A 21-yr-old female weightlifter presented with acute anterior hip and groin pain after an injury sustained while back squatting. The athlete described a painful pop in the anterior hip while at the bottom of a back squat with a load of 117 kg. On initial presentation, the athlete was ambulatory with a significant limp and described the hip flexion phase of gait to be the most painful.

On physical examination, marked tenderness to the AIIS and proximal rectus femoris was noted. Hip active range of motion was full for abduction, adduction, and extension; however, flexion above 90 degrees could not be performed due to hip pain. Rotation ranges of motion of the hip were full and nonpainful in the neutral position. The patient could not perform an active straight leg raise due to anterior hip pain localized to the proximal rectus femoris. Knee extension was painful, with 4/5 strength with manual muscle testing. Orthopedic examination at the time of injury was limited due to pain with hip flexion above 90 degrees of motion.

A working diagnosis of a proximal rectus femoris strain was made. Musculoskeletal ultrasonography of the anterior hip and pelvic radiographs was obtained to determine the extent of pathology and to rule out osseous involvement. No joint effusion was present. The visible portion of the anterior labrum was intact. Examination of the proximal rectus femoris tendon showed cortical irregularity at the distal aspect of the anterior inferior iliac spine measuring 1.2 cm, cortical irregularity at the femoral head neck junction measuring 1.1 cm, and an anechoic cleft within the substance of the rectus femoris tendon (Figs. 1 and 2). Power Doppler showed imaging was consistent with increased blood flow at this location. This examination confirmed rectus femoris proximal tendon partial tear, with sonographic findings suggestive of previously existing tendinosis.

Figure 1

Figure 1

Figure 2

Figure 2

Conservative management was initiated. This program consisted of protection of the injury with a hip spica wrap and 50% weight bearing with axillary crutches, gentle range of motion, quadriceps isometrics, massage, and cryotherapy with compression. Over the next 14 d, with the addition of formal physical therapy, the patient regained the ability to perform an active straight leg raise with minimal discomfort and was able to ambulate without assistance. However, on repeat examination, hip flexion range of motion above 90 degrees elicited significant pain. Special tests also were provocative (Table). Pain when twisting over her hip, such as getting in and out of a car, was noted. A noncontrast 3 T magnetic resonance imaging (MRI) of the hip was performed and was positive for a detached labral tear (Fig. 3A), chondral thinning along the anterolateral weight-bearing aspect of the acetabulum, and a proximal rectus femoris strain with possible avulsion at the anterior inferior iliac spine (Fig. 3B). The alpha angle measured 57 degrees, the center edge angle 28 degrees, and femoral anteversion 3 degrees. Radiographs demonstrated mixed type FAI with alpha angle greater than 55 (17), positive crossover sign, and an element of SSI (Fig. 4). Based on these findings and the lack of improvement, the patient was referred to an orthopaedic surgeon, and hip arthroscopy was recommended.

Table

Table

Figure 3

Figure 3

Figure 4

Figure 4

At hip arthroscopy, a bruised labrum was identified at the point of contact with the cam lesion. The labrum failed to maintain a seal with the femoral head (Fig. 5). A bur was used to restore the femoral head-neck offset. Limited rim trimming was performed to remove the pincer lesion. A bur also was used to decompress the low AIIS and area of SSI. A chondral defect of the acetabulum was treated with chondroplasty. The labral tear was repaired using three anchors (20).

Figure 5

Figure 5

Postsurgical rehabilitation began with stationary bike and isometrics strengthening of the trunk and hip. Rehabilitation recommendations included flat foot weight bearing (20 pounds of pressure) for 3 wk, abduction of 0 to 45 degrees for 2 wk, wearing a brace while ambulating for 3 wk, 10 to 45 degrees of continuous passive motion for 4 wk, and avoiding the hip at 90 degrees of flexion. The patient was able to return to full sport participation 5 months after surgery. At 11 months, she was able to compete at 100% of her prior level.

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Discussion

This case describes the natural history and clinical decision-making process in a patient with SSI of the hip. Anterior hip pain can be a challenging complaint for the sports medicine physician (4,22). SSI is a relatively new diagnostic entity with limited description in the literature (2,3,11,19,21). Symptoms of atypical impingement in the hip (such as SSI) are frequently nonspecific, and therefore imaging can play a vital role in the diagnosis of SSI and other causes for extraarticular impingement (11,14,21). Clinical findings of pain at the AIIS with passive hip flexion, proximal quadriceps pain and weakness, and painful impingement tests of the hip may be indicative of the presence of SSI (8,11,19). Arthroscopic treatment for SSI along with treatment of a labral tear and mixed type FAI allowed an elite athlete to return to a previous level of sports participation.

The symptoms of SSI include anterior hip pain with flexion, pain with palpation of the anterior inferior iliac spine, limited hip range of motion, and little relief with an intraarticular anesthetic injection (3,11,19,21). SSI usually occurs in male patients who are under the age of 30 yr (21). Other studies have shown that patients treated for SSI have improved motion and function and return to activity (8,11).

This patient also presented with a tear of the deep fibers of the rectus femoris, which is a common site of injury (6). Strains of the hip flexor can occur during unusual muscle contraction or during times of high-velocity hip flexion (6,21). Symptoms of a hip flexor strain have been reported as the feeling of a severe pop and instant pain in the anterior hip (6). Avulsions of the proximal rectus femoris and AIIS are rare and usually occur in adolescents or high impact sports (5).

Although most cases reported in the literature describe SSI as occurring secondary to chronic injury, the patient in this case had acute onset of pain in the quadriceps during a squat and a subsequent finding of labral tear. The authors propose the acute quadriceps tear injury occurred due to anterior pelvic tilt with squatting and chronic attrition to the deep fibers of the rectus secondary to repetitive squatting with a congenitally hypertrophic AIIS. As a result of the acute tear, the athlete then fell deeper into the squat, resulting in an acute anterior labral tear.

A comprehensive physical examination, anterior posterior (AP) and cross table lateral radiographs and high-resolution MRI of the hip can be useful in making a correct diagnosis (14). Musculoskeletal ultrasound may be used for evaluation of the proximal quadriceps tendon and superficial soft tissues of the anterior hip. Management of SSI should begin with physical therapy. Physical therapy may include hip strengthening with avoidance of hip flexion greater than 70 degrees (12). Exercises to control anterior pelvic tilt protect the proximal rectus tendon from impingement injury leading to tendinopathy; however, more research is needed. Failure to respond to physical therapy is indication for referral to an orthopedic surgeon with training in hip arthroscopy. Surgical approaches to SSI may include trimming of the bone based on the area of damage caused by the impingement.

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Conclusion

This is a case of SSI with associated FAI and a labral tear. The main diagnostic tools used included a comprehensive physical examination, radiographs, and a 3-T MRI. This case provides beneficial information for other health care providers in diagnosing and treating this unusual and challenging injury. The patient was able to return to elite weightlifting at 100% her prior level 11 months after surgery. With the proper diagnosis and treatment, an athlete with these injuries can return to competitive sports after comprehensive care.

MJP recieves royalties form Smith & Nephew, Arthrosurface, Bledsow, ConMed Livatec, and DonJoy. MJP is a stockholder in Arthrosurface, MJP Innovations, LLC, and MIS. Research support received from Ossur, Arthrex, Siemens, Smith & Nephew, and Vail Valley Medical Center.

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