Femoroacetabular dislocations are typically associated with high-energy trauma, such as motor vehicle accidents, and are often accompanied by fractures of the acetabulum, femoral head, and femoral neck. While rare, these injuries can occur during routine sporting activity. The majority of hip dislocations occur in a posterior direction (Fig. 15.3). With or without associated fractures, rapid reduction of the dislocation is paramount in order to decrease the risk of osteonecrosis. Mehlman’s longitudinal study of pediatric dislocations found a 20-fold increase in the rate of osteonecrosis when reduction was delayed more than 6 h [7]. Osteonecrosis of the femoral head is one of the most feared complications of a hip dislocation as it is difficult to treat, and rates vary widely in the literature [8].

Reduction may first be attempted with appropriate sedation and analgesia through a variety of traction maneuvers. Failure may necessitate reduction under general anesthesia or an open reduction. Dislocations with associated fractures, such as those to the acetabulum or femoral head, should be treated urgently; most commonly, this involves open reduction and internal fixation . If appropriate resources are not available at the initial treating facility, strong consideration should be given to referral to a facility with experience and personnel to definitively treat both the dislocation and any associated injuries. After reduction, advanced imaging, including magnetic resonance imaging (MRI) and/or CT, should be used to verify a concentric reduction, assess for occult fractures, evaluate for any loose bodies incarcerated within the joint, and define associated chondral or labral injuries. A high rate of intra-articular pathology has been documented after traumatic hip dislocations. Fractures are typically treated with open procedures, while loose bodies and chondral or labral injuries are amenable to arthroscopic treatment [9, 10]. Follow-up MRI at 3 months is recommended by some to detect early signs of osteonecrosis [8].

Reduced hips without associated fractures have typically been treated with immobilization in young children for 3–4 weeks and weight-bearing restrictions in older patients for 6–12 weeks. Good outcomes have been observed in children, however older athletes may have more difficulty returning to high-level sports. Patients with traumatic hip dislocations are more likely to have pre-existing impingement morphology and increased acetabular retroversion, which may predispose them to a posterior dislocation event and could make recovery after a dislocation more difficult [11].

Recognition of hip instability as a cause of hip pain and dysfunction has grown over the last several years. Instability of the hip can be classified as either traumatic or atraumatic. Traumatic hip instability results from an acute event that damages the osseous or soft-tissue structures of the hip leading to a transient loss of concentric femoroacetabular reduction. An initial traumatic instability event may lead to persistent subacute subluxation or micro-instability episodes due to capsular attenuation or compromise of the dynamic periarticular stabilizers. If a trial of conservative treatment does not resolve instability symptoms, surgical intervention may be necessary to address the offending pathology.

Surgical treatment may be directed at contributions to instability from bony architecture, the hip joint capsule, or other soft-tissue structures in any combination. As arthroscopic hip surgery continues to grow in popularity, it is important to recognize that instability can also be the result of an overzealous capsulotomy performed during prior hip arthroscopy. While some postulate that strategic capsulotomy or capsulectomy may be a therapeutic treatment for hip stiffness, intra-operative capsulotomies disrupt important capsuloligamentous stabilizers. In recent years, a more judicious approach towards capsular management has been adopted and capsular repair has gained support. Various capsular repair methods have been described, but no consensus exists regarding their efficacy or necessity [12].

Atraumatic instability is believed to result from repetitive microtrauma, which eventually leads to capsular attenuation and chondrolabral pathology [12]. Posterior instability in an athlete has also been shown to demonstrate a strong relationship with FAI morphology. According to this proposed mechanism, anatomic conflict between the femoral head/neck junction and the acetabulum may cause the femoral head to lever posteriorly out of the acetabulum [13, 14]. The joint may also be susceptible to atraumatic instability due to acetabular dysplasia (DDH), Legg–Calvé–Perthes disease , or systemic conditions that result in ligamentous laxity such as Marfans or Ehlers–Danlos syndromes, as well as patients who have undergone bariatric surgery [15]. Treatment is highly dependent on the specific pathology, though it is important to understand the limitations and dangers of arthroscopic treatment for patients with dysplastic morphology. Surgical options to address capsular laxity include thermal capsulorraphy or suture plication [16]. Bony abnormalities, such as FAI or DDH, are treated with targeted decompression of the offending structures or rotational osteotomy to provide further structural support. Hip arthroscopy alone is contraindicated in patients with significant DDH.

Proximal femoral fractures are rare in sports and usually are associated with high-energy trauma. Femoral neck fractures represent a surgical emergency and may have catastrophic long-term consequences if not treated in a timely manner. Concomitant injury to the tenuous vascular supply increases the risk of femoral head osteonecrosis. The causal relationship between time to reduction and osteonecrosis is less established than what is seen with traumatic hip dislocations. Furthermore, the type of fracture and quality of reduction may also have important prognostic implications for an athlete’s long-term outcome. Capsular decompression after reduction and fixation has been advocated to decrease intra-articular pressure on the femoral head vascular supply [17]. Surgical stabilization is the mainstay of treatment for traumatic hip fractures, and a variety of fixation methods can be employed, depending on the specific fracture pattern and associated injuries. Typically, femoral neck fractures are stabilized with either multiple cannulated screws placed from lateral to medial across the fracture site or with a sliding hip screw and side-plate construct [18]. More distally, fractures of the intertrochanteric and subtrochanteric region can be treated with a variety of implants including sliding hip screws, cephalomedullary nails, and plate and screw constructs depending on fracture characteristics and surgeon preference.

In contrast to traumatic fractures, stress or fatigue fractures are overuse injuries. These are typically encountered among athletes who increase their training regimen, especially runners . Military personnel are also at risk due to the intensity of their conditioning. Appropriate imaging can be obtained to accurately confirm a suspected diagnosis. While many lesions may not be apparent on plain radiographs, MRI offers high sensitivity for stress fractures or stress reactions in addition to anatomic specificity [19]. MRI findings may include edema within the bone or a distinct fracture line. Certain stress fractures, including tension-sided fractures of the femoral neck, are at a higher risk for progression or displacement and may be treated more aggressively [20]. Lower risk stress fractures, such as those of the pubic ramus, can be treated with activity modifications. The clinician should be aware of and address contributing factors such as leg-length discrepancies or malalignment, femoroacetabular impingement, or acetabular dysplasia, which may alter hip joint arthrokinematics and place excess stress on adjacent structures. It is important to explore and treat any underlying metabolic bone disorders, patterns of nutritional insufficiency, and systemic medical disorders, as these may predispose athletes to stress fractures [21]. The female athlete triad represents a common spectrum of metabolic and nutritional compromise that can occur in the presence of over-training, placing an athlete at an increased risk for injuries of attrition.

Missed femoral neck fractures can lead to disastrous consequences if not treated appropriately and in a timely fashion. Thus, the index for suspicion for these injuries should be high and the threshold for obtaining advanced diagnostic imaging should be low [22]. Diagnosis typically includes the use of radiographs and MRI. Multiple classification systems have been described, most of which discriminate between compression and tension-sided lesions and displaced fractures. Displaced fractures are generally a surgical emergency. These are treated with anatomic reduction followed by fixation with either cannulated lag screws or a sliding hip screw [23]. Non-displaced compression-sided fractures (found on the medial or inferior aspect of the femoral neck) are more inherently stable and may be treated with limited weight-bearing for 6–12 weeks if they are less than 50 % of the width of the neck. Fracture line extension beyond 50 % of the width of the neck warrants consideration for internal fixation. Most authors advocate fixation of tension-sided injuries, however successful conservative treatment with close follow-up has been reported [24]. Failure of non-operative treatment is an indication for operative intervention (Fig. 15.4). For non-displaced fractures, surgical stabilization often includes percutaneous placement of two or three cannulated lag screws across the femoral neck or a sliding hip screw and side-plate construct followed by a period of restricted weight-bearing. Patients with compression-sided injuries treated operatively may be able to progress weight-bearing earlier or even immediately, depending on their relative stability [25]. Complications after surgical stabilization include those related to hardware irritation and periarticular soft-tissue disruption during fixation, therefore, an attempt at non-operative treatment is preferable when possible.

Muscle strains of the hip and pelvis are among the most common injuries an athlete can sustain in this anatomic region. They often occur during eccentric contractions and are more common in muscles that cross two joints. They occur most frequently at the myotendinous junction , but are also seen in the muscle belly [1]. In addition to clinical examination, advanced imaging may be helpful in both determination of the diagnosis and the prognosis. Plain radiographs may detect avulsion fractures. MRI can offer further detail regarding the nature of the soft-tissue injury, and the degree of injury seen on MRI has been shown to correlate with time until return to activities [26].

Treatment initially consists of non-steroidal analgesics and local measures to reduce hemorrhage and edema, including ice, elevation, and compression. NSAIDs are also considered to prevent heterotopic ossification or myositis ossificans. Range of motion and then strengthening are progressively introduced as pain improves [1]. Occasionally, however, surgical intervention is required. Following failure of functional rehabilitation, patients with chronic pain from tears of the proximal rectus femoris musculotendinous junction have been shown to respond favorably to excision of their scar tissue [27]. Others have reported success after unilateral or bilateral adductor tenotomies for chronic groin pain from adductor tendinopathy in athletic populations [28–30]. Recently introduced non-surgical modalities such as instrumented or manual myofascial treatments or Active Release Technique (ART) have gained popularity for the treatment of periarticular myofascial scarring, connective tissue adhesions, or soft-tissue contractures that may develop as sequelae of muscular sprains or strains [31].

Avulsion fractures are less common in skeletally mature athletes . These occur in the same manner as their corresponding soft-tissue injury, and could occur at any muscular attachment with sufficient force. Displacement is limited by periosteum and surrounding fascia. These have been reported to occur with low energy trauma in patients with underlying malignancy, notably around the lesser trochanter [32]. Surgical treatment may be indicated when there is greater than 2 cm of displacement and the fragment is large enough for fixation, or if conservative management fails to allow healing [1].

Injuries to the proximal hamstring tendon complex have gained attention in recent years. These injuries commonly occur suddenly with the leg in a position of hip flexion and knee extension. Partial and full thickness injuries to any one of the three tendons of the proximal hamstring complex have been described. Surgical intervention is generally recommended for patients with an avulsion of at least two tendons, retraction greater than 2 cm, and for those with the desire to resume high-demand physical activity. Failure of conservative treatment may also constitute an appropriate indication for operative repair. A growing body of evidence now supports surgical repair for partial thickness, full thickness, and chronic full thickness tears [33]. The anatomic footprint of the proximal hamstring has been extensively cataloged in recent reports [34]. Advanced imaging, such as MRI, can be an invaluable tool to confirm the diagnosis of a proximal hamstring injury and grade the extent of the pathology. Surgical repair is conducted through an open longitudinal incision for a large retracted tear or chronic tear with nerve entrapment. When the tear is small or partial thickness, surgical repair may be accomplished through a transverse subgluteal incision, which is more cosmetic. Arthroscopic repair techniques have also been described and early reports reflect good and excellent outcomes with minimal soft-tissue morbidity [35]. Limited results reported in the literature have been generally good with regard to return to sport and strength for both full and partial thickness tears [36, 37].

Femoroacetabular impingement (FAI ) is an increasingly recognized source of pain and functional impairment in active individuals. It is believed to result from morphologic alterations of the acetabulum and/or proximal femur (Fig. 15.5), which can lead to pathologic anatomic conflict, labral and chondral injuries, and synovitis. FAI has been causally linked to the progressive development of early onset osteoarthritis (OA) of the hip, though this is somewhat controversial [38].

Imaging is helpful for the diagnosis of FAI and for surgical planning, but it is important to note that FAI is a dynamic phenomenon and may occur in the absence of significant radiographic deformity in positions of extreme hip motions, such as those encountered during martial arts and dancing [39]. The presence of significant OA on weight-bearing radiographs is a poor prognostic indicator of clinical outcomes following arthroscopic hip surgery. While diagnoses can be made provisionally with plain radiographs, MRI and CT are more sensitive for uncovering more subtle abnormalities, gaining a more sound understanding of the global pathomorphology of the joint, and diagnosing associated pathologies prior to surgery [40].

Surgical intervention is indicated when symptomatic FAI does not respond to an appropriate period of rest, activity modifications, and non-steroidal anti-inflammatory medications. Thorough pre-operative workup should be conducted to fully characterize the bony morphology of the joint as well as the degree of labral and chondral pathology that is present. Initially, open surgical hip dislocation was described to safely access symptomatic pathology within the central and peripheral aspects of the hip joint [41]. More recently, arthroscopic techniques have been increasingly utilized to address symptomatic FAI as well as synovial, labral, and chondral disease [3]. Bozic et al. reported a 600 % increase in the incidence of hip arthroscopies performed by orthopedic surgeons undergoing board certification between 2006 and 2010 [42], while Colvin et al. found an 18-fold increase in the number of hip arthroscopies performed during a study period of 1999 to 2009 [43]. Though preferable to many surgeons, it is important to recognize the limitations of arthroscopy. Cam deformities are typically most severe at the anterosuperior head–neck junction of the proximal femur, which is readily accessible by arthroscopic means. Lesions that extend posteriorly approach the lateral retinacular vessels of the posterolateral neck, and thus they are less accessible and the dissection is more dangerous. Complex lesions , such as deformities from pre-existing Legg–Calvé–Perthes or slipped capital femoral epiphysis (SCFE), may also be difficult to adequately treat arthroscopically. Often these more global pathologies, rotational deformities, or abnormalities of version need to be treated concomitantly and require a more aggressive open approach [44].

Regardless of whether an open or arthroscopic approach is used to access the joint, goals for thorough FAI treatment involve bony decompression and stabilization of associated labral and chondral injuries. Treatmen t typically involves some combination of a femoral head–neck osteochondroplasty, acetabular rim osteoplasty, labral repair or debridement, and acetabular chondroplasty. Less frequently, an acetabular osteotomy may be indicated for more significant global acetabular retroversion or volume deficiency. Dynamic examination under fluoroscopic or arthroscopic visualization can be used to confirm appropriate resection of bony deformities prior to the conclusion of the procedure [3, 45].

Outcomes following both open and arthroscopic hip surgery are generally favorable [46, 47]. Factors associated with improved outcomes include the absence of significant OA [48], labral repair versus debridement [49], and proper recognition and complete treatment of associated bony pathology [50]. In the absence of significant OA, age should not be a deterrent to arthroscopy [51]. Arthroscopy should be avoided in patients with evidence of dysplasia, as surgery may lead to iatrogenic instability and accelerate degenerative progression in certain cases [52].

The acetabular labrum is a fibrocartilaginous ring that surrounds the bony acetabulum. It deepens the hip socket, maintains the intra-articular fluid-film layer, and creates a negative pressure seal within the joint. Free nerve endings have been found throughout the labrum, but are most densely located at the anterosuperior aspect [53].

Acetabular labral injuries can occur with or without underlying bony abnormalities, such as FAI. Labral pathology rarely results from acute injuries, including major trauma as well as minor twisting events or falls. More commonly, labral damage occurs as part of a global attritional process, such as OA. Labral injuries tend to result from a shearing mechanism and are typically oriented perpendicular to the articular surface at the chondrolabral junction or within the substance of the labral tissue in cases of degenerative pathology. They are often associated with adjacent acetabular chondral lesions [3], and most pathology is found in the anterosuperior quadrant [54]. When a labral tear is suspected, confirmatory MRI or MRA can be used to verify the diagnosis (Fig. 15.6). The addition of arthrography may enhance visualization of labral or chondral pathology and aid in pre-operative planning [55]. Ultrasonography can be used to detect labral pathology, paralabral cysts, and adjacent injuries within the periarticular soft tissues and may present an alternative imaging modality to aid in formulating an accurate diagnosis.

The natural history of labral pathology is poorly defined, and a course of non-operative treatment is usually initiated before considering more invasive options. A high rate of chondral and labral pathology has been demonstrated in populations of asymptomatic volunteer subjects, strengthening the importance of an appropriate course of non-operative treatment prior to considering surgical intervention [56]. Conservative treatment includes some combination of activity modification, physical therapy, and anti-inflammatory medications. Intra-articular anesthetic or anti-inflammatory injections are commonly used for pain mapping and to improve diagnostic accuracy. A positive response to an intra-articular injection may have prognostic importance when used to predict outcomes following arthroscopic hip surgery [57, 58]. Intra-articular cortisone injections may be limited long-term benefit, however, when employed in a therapeutic role [59].

Hip arthroscopy is becoming a popular tool to access the joint and treat labral, chondral, or synovial pathology (Fig. 15.7). After appropriate arthroscopic visualization, the labrum is debrided of any nonviable tissue using arthroscopic shavers, biters, or radiofrequency ablation. Any remaining tissue that can be repaired is reattached to the underlying bone using suture anchors. Prior to suture repair, the acetabular rim is often freshened or trimmed to remove any areas of focal overcoverage and expose a bleeding bone surface, which may optimize the biologic healing response. Sutures may be passed through the labrum in a mattress fashion or around the damaged tissue in a looped configuration [3]. The arthroscopic treatment of labral pathology has been shown to yield favorable and durable results, however the presence of significant OA has been shown to be a poor prognostic factor and increases the chance of conversion to arthroplasty [60].

Labral reconstruction is utilized when severe injury or previous debridement has left the acetabular rim devoid of a functioning labrum. Various graft choices, including allograft and autograft, have been reported in the literature [61]. Both open and arthroscopic methods are described [62]. Biomechanical [63]. and short-term functional results [61, 64]. show promise, but long-term follow-up has yet to be reported.

The concept of femoroacetabular impingement has evolved to include patterns of bony impingement that occur between anatomic regions outside the intra-articular space. The so-called extra-articular impingement can cause pain and loss of function in athletes. In contrast to intra-articular impingement, extra-articular pathology encompasses a number of much less common conditions, and treatment strategies are evolving. Abnormal bony contact and soft-tissue compression are responsible for symptoms. Various etiologies include psoas impingement, subspine impingement, ischiofemoral impingement, and greater trochanter/pelvic impingement [65].

Psoas impingement (PI) involves atypical labral wear in the direct anterior position secondary to compression or traction from the adjacent iliopsoas tendon. These distinct labral tears are found anterior and inferior (3 o’clock or 9 o’clock) to the typical location caused by intra-articular impingement. This pattern of impingement may cause anterior hip pain over the iliopsoas at the level of the anterior joint line and pain with hip flexion. Initial treatment may include activity modifications and focused rehabilitation. Refractory symptoms can be treated with image guided iliopsoas injections or arthroscopic fractional lengthening of the i liopsoas tendon along with appropriate labral and chondral treatment [66].

Subspine impingement (SSI) occurs when there is abnormal contact between the distal femoral neck and the undersurface of the anterior inferior iliac spine (AIIS) . Prominence of the AIIS can be secondary to prior apophyseal or rectus avulsions, periacetabular osteotomies, acetabular retroversion, or developmental variants. SSI typically manifests as pain with hip flexion, limited hip flexion range of motion, and pain directly over the AIIS. Failure of conservative management, including rest and injections, can be treated with arthroscopic subspine decompression, which has been shown to improve both pain and functional symptoms [67].

Ischiofemoral impingement (IFI) is a less commonly reported form of extra-articular impingement and is caused by static or dynamic narrowing of the area between the ischial tuberosity or posterior acetabular rim laterally and the lesser trochanter or posterior greater trochanter medially. It can be associated with the sequelae of Perthes disease or otherwise morphologically abnormal hips. Surgical treatment involves open resection of the often-prominent lesser trochanter [68].

Greater trochanteric/pelvic impingement (GTPI) results from abnormal contact between the greater trochanter and the ilium, and is also often associated with abnormal hip morphology . Pain occurs with the hip in abduction and extension. Numerous open surgical treatments including osteotomies of the greater trochanter and acetabulum, rotational osteotomy, or arthroscopic decompression have been described [65].

Coxa saltans, or “snapping hip,” is an audible and potentially painful snapping about the hip during motion. It has multiple distinct etiologies. External snapping hip is caused by pathologic thickening or contracture of the posterior one-third of the iliotibial (IT) band or from pathologic translation of the gluteus maximus over the posterolateral border of the greater trochanter. Internal snapping hip results from translation of the psoas tendon over the femoral head, iliopectineal eminence, or the AIIS. Intra-articular snapping can be caused by loose bodies or labral pathology [69].

Treatment for coxa saltans depends on the severity and duration of symptoms. Most cases are minimally symptomatic, especially in athletic populations who can develop snapping due to the demands of repetitive training. Activity modification, anti-inflammatory medications, local injections, and focused hip and pelvic rehabilitation are effective strategies for most patients. When these measures fail, surgical intervention is indicated. Mechanical symptoms originating from an intra-articular source are typically due to an unstable labral tear or chondral flap. Arthroscopy is an effective tool used to address the offending pathology, which is typically due to an unstable labral tear or chondral flap [70].

Internal snapping hip can be treated by lengthening or release of the iliopsoas tendon. Traditionally, an open approach was described to lengthen the tendinous portion using multiple transverse incisions. Lengthening can be made at the level of the femoral head or the pelvic brim [69]. Arthroscopic techniques have become more popular with technical evolutions in hip arthroscopy [71]. Arthroscopic fractional lengthening can be performed at the level of the lesser trochanter using fluoroscopic assistance, or through a transcapsular window under direct arthroscopic visualization inside the joint. Arthroscopic lengthening offers the potential advantages of a less invasive approach and fewer complications compared with open techniques [72].

External snapping is typically treated with open or endoscopic trochanteric bursectomy with fractional lengthening of the thickened portion of the IT band or gluteus maximus. Multiple lengthening procedures have been described, including open Z-plasties, transverse releases, cruciate incisions, and tenodesis procedures [73, 74]. Attention should be paid to abnormal morphology or malalignment, such as coxa vara, which may predispose patients to this condition [75]. More recently, endoscopic techniques have emerged in the literature with promising short-term results. Endoscopic options utilize various strategies to relax or release the contracted portion of the IT band or gluteus maximus tendon [76, 77].

Reproducible tenderness over the greater trochanter can be due to numerous pathologies of the peritrochanteric space including trochanteric bursitis, abductor tearing, external coxa saltans, or even referred intra-articular pain [78]. The gluteus medius and minimus , which comprise the majority of the hip abductor complex, have been described as the “rotator cuff of the hip.” Inflammation or scarring of the overlying trochanteric bursa can also lead to chronic pain and dysfunction. Much like the shoulder, there is a high prevalence of asymptomatic tendinopathy and tearing that advance with age [3, 79]. Both MRI and musculoskeletal ultrasonography (MSUS) are highly accurate imaging modalities to characterize the extent of abductor disease [80, 81].