Panel discusses new types and treatments for hip impingement

Femoroacetabular impingement has been a topic of substantial interest and investigation. Classically described as an anterolateral bump at the femoral head-neck region (cam femoroacetabular impingement) and focal or global acetabular over coverage (pincer femoroacetabular impingement), fresh concepts and controversies have emerged. I have sought the input of an esteemed panel to discuss some new and unusual types of femoroacetabular impingement and extra-articular hip impingement.

Dean K. Matsuda, MD
Moderator

Dean K. Matsuda, MD: Before we delve into newer types of hip impingement, what are your thoughts regarding the treatment of global pincer femoroacetabular impingement (FAI), i.e., coxa profunda and acetabuli protrusio?

Robert T. Trousdale, MD: Global impingement occurs in two clinical scenarios, either coxa profunda or acetabuli protrusio which is defined by the magnitude of how profound the global over-coverage is. Coxa profunda is defined as the ilioischial line crossed by the floor of the acetabulum, and protrusio is defined by the fact that the medial part of the femoral head is medial to the ilioischial line. Both of those conditions, in my mind, should be treated nonsurgically initially. There are a lot of etiological causes with these deformities. If the nonoperative things have failed and if the pain is bad enough to warrant surgical intervention, then one should assess the status of the articular cartilage closely. If the cartilage is in poor shape, those patients are probably best treated with a total joint replacement (TJR). If the cartilage is in good shape and the pain appears to be mechanical in nature, in my mind, these are best treated with an open surgical dislocation.

Even well-versed arthroscopists have a difficult time treating the posterior compartment of the hip joint. We treat these patients with global rim resection and labral reconstruction and/or reattachment depending on the status of the labrum. In light of the fact that the coverage is global, typically pelvic osteotomies have a limited role for those patients.

Christopher M. Larson, MD: Global over-coverage is observed more frequently in women and is typically associated with a lateral center edge angle (LCEA) greater than 40° with “global” anterior, lateral and posterior acetabular over-coverage. Focal over-coverage, on the other hand, is most frequently anterior acetabular over-coverage, often in the setting of cranial acetabular retroversion, with normal lateral (LCEA 25° to 40°) and normal posterior coverage (negative posterior wall sign [PWS]).

Although focal anterior over-coverage can be predictably managed with an arthroscopic approach, the ideal surgical treatment and approach for global pincer-type FAI is controversial. For profunda hips, arthroscopic and open global rim resections can be performed but these are more challenging arthroscopically and require experience. The posterior rim resection is the most challenging portion arthroscopically and can be facilitated with a short period of increased traction and establishment of a posterolateral portal.

Protrusio is a much more complex pathomorphology and is often associated with proximal femoral-sided deformities (i.e., coxa vara). Although some cases of protrusio can be managed by an experienced arthroscopist, I believe it is most predictably managed with an open approach in most cases. If the lunate fossa and sourcil are relatively normal, then rim resection is an option which can be done via surgical hip dislocation or by an experienced hip arthroscopist. If the lunate fossa is large and associated with a shorter sourcil, rim resections should be avoided in order to prevent increased medial femoroacetabular contact pressures. Pelvic and or femoral-sided osteotomies might be most appropriate in this situation.

Matsuda: The classic cam deformity was described as an anterolateral bump. How has our understanding and treatment of cam FAI evolved?

Larson: Cam morphology is a 3-D deformity, and the extent is variable between patients. Anteromedial extension (Figures 1a and 1b) can occur to or beyond the medial synovial fold (MSF)/vessels and often extends distally along the MSF. The medial femoral neck can contact the anterior rim and/or anterior inferior iliac spine (AIIS) in flexion and flexion/internal rotation (IR) positions. Femoral resections along the MSF region may be critical to maximize straight hip flexion and IR clearance postoperatively.

Trousdale: The classic cam deformity has been well-described in the literature. The natural history of this deformity is not well elucidated. Recently, at this year’s American Academy of Orthopaedic Surgeons Annual Meeting, the Salt Lake City group documented that this deformity is common in senior athletes and, interestingly, these active athletes do not all develop arthritis. This emphasizes the need to treat these patients nonsurgically initially. Joint salvage surgery should only be entertained in symptomatic patients and in patients with viable cartilage. The fact that a lot of the senior athletes do not develop end-stage hip arthritis re-emphasizes the role for nonsurgical management, at least initially, in these patients. That, of course, is different in patients who have major structural problems at a relatively young age. There might be some justification in being more aggressive in that patient population.

Matsuda: How does one diagnose and treat posterior FAI? Can posterior cam deformity be treated arthroscopically or should it be done via open surgical dislocation?

Trousdale: Posterior cam impingement certainly occurs. The natural history of posterior impingement is not known. If nonoperative treatment has failed and there is viable articular cartilage, these patients are best treated with probably an open surgical dislocation. If the cartilage is damaged and if the nonoperative treatment has failed, they are best treated with a TJR.

Larson: Posterolateral cam deformity that extends beyond the lateral retinacular vessels and is visible on an AP radiograph can be managed with an arthroscopic approach with experience. Hip extension and, in some cases, traction allows the surgeon to resect the deformity beyond the lateral vessels while staying proximal to them. Directly posterior cam deformities that are visualized on lateral radiographs are not predictably accessed arthroscopically, and although uncommon, are best managed with a surgical dislocation when symptomatic.

Matsuda: How does femoral version affect FAI and what is your preferred treatment?

Hal D. Martin, DO: The hip functions in an optimal balance between instability and impingement in three planes of hip motion dependent on the osseous, capsulolabral, musculotendinous, neurovascular structures and kinematic chain. FAI is one side of the equation and can co-exist with instability in a single case, which depends on all structure levels, especially 3-D osseous femoroacetabular geometry. Decreased femoral anteversion or acetabular version is subject to rim overload or impingement. Conversely, excessive acetabular anteversion or femoral version greater than 30° is subject to instability.

The language of dynamic or static overload has been introduced by Kelly and colleagues to explain the relationship between the femur and acetabulum. Usually, the acetabular labral rim can be shaped without labral take down in cases of -5° or less of femoral version and has been determined to produce confirmed favorable outcomes with ranges of femoral version +5° to 20°.

Cases of non-compensated retroversion greater than or equal to 5° with adequate acetabular orientation are treated by de-rotational osteotomy at a single femoral level. De-rotational osteotomies may be performed using recently published closed intramedullary (Figure 2) or more established open techniques. Compensated femoral retroversion requires consideration of the bimalleolar and tibial torsion, and the entire lower leg biomechanical axis.

Trousdale: Femoral version does affect the range of motion (ROM) of the hip and secondary impingement. It is important to define whether the version abnormality is proximal to the trochanteric line or if the torsional abnormality is distal to the intertrochanteric line. Most of these patients who have mild version abnormalities can be treated nonsurgically, but if they have marked abnormality of foot progression angle and it is documented that the version is markedly abnormal, I would treat these patients with an open de-rotation osteotomy. The location of that osteotomy is probably best served in the location where the deformity is located. If there is an anteversion issue that is proximal to the lesser trochanter, I would do an intertrochanteric osteotomy. If it is a torsional problem distal to the lesser trochanter, I would do a subtrochanteric de-rotation osteotomy.

Matsuda: What is subspine impingement? How is it diagnosed and treated?

Larson: Subspine impingement occurs when the AIIS contacts the anterior and/or medial femoral neck with flexion/internal rotation and straight hip flexion, respectively. This can be secondary to a prior AIIS apophyseal avulsion deformity, prior rectus femoris rupture with ossification of the proximal tendon, prior periacetabular osteotomy (PAO) with overcorrection or seen in the setting of acetabular retroversion with a developmentally prominent AIIS. In addition, hyperflexibility athletes (dancers, gymnasts or hockey goalies) can have subspine impingement secondary to supraphysiologic ROM requirements. The AIIS can be prominent anteriorly and/or distally, and the false profile radiograph and 3-D CT scans best depict the deformity.

A distal extension to or beyond the acetabular rim anteriorly is considered abnormal. These patients typically have pain with straight forward hip flexion, often TTP over the AIIS that recreates the presenting symptoms, and capsular/labral ecchymosis in the region of the AIIS at the time of surgery. When symptomatic, subspine decompression can be predictably performed arthroscopically and a window made in the anteromedial capsule can help facilitate these decompressions and still allow for capsular repair at the conclusion of the procedure when desired.

Matsuda: What is ischiofemoral impingement (IFI)? Do you prefer decompression with osteoplasty of the lesser trochanter or the lateral ischium?

Larson: I rarely encounter symptomatic IFI in patients, and my approach is based on the deformity/pathology. If secondary to prior ischial apophyseal avulsion deformity, I excise the ischial deformity open followed by repair of the hamstrings (Figures 3a and 3b). If the ischium is normal and the proximal femur has relatively normal version and neck shaft angle, I decompress the lesser trochanter with an endoscopic technique anteriorly (psoas bursal approach). In two cases, I have seen cortical hypertrophy of the ischial tuberosity with hamstring tearing and performed an open hamstring takedown, ischial decompression, hamstring repair and endoscopic lesser trochanteric decompression. If there is excessive coxa valga and femoral anteversion/torsion, I would consider a de-rotational femoral osteotomy.

Martin: IFI is not a radiographic diagnosis. Symptomatic IFI presents as pain lateral to the ischium correlated to the IFI test (reproducible pain lateral to the ischium in terminal hip extension, neutral abduction, alleviated by hip abduction and terminal hip extension) and increased pain with long stride walking lateral to the ischium. The causes may be related to the entire biomechanical three planar axes involving the osseous, capsulolabral, musculotendinous, neurovascular or kinematic chain pathology. The treatment goal is the restoration of normal ischiofemoral space, which requires an understanding of the cause.

IFI is not related to lesser trochanteric version, but is related to increased femoral version. Based on case specific clinical and radiographic findings, treatment can be nonoperative or operative with isolated resection of the lesser trochanter, ischioplasty, de-rotational or varus femoral osteotomy dependent upon the etiology. A final thought on IFI is that lack of terminal hip extension can lead to SI joint or lumbar spine compensation or complaint. We call the recreation of pain in these locations from lack of terminal hip extension a positive hip-spine test.

Matsuda: What is greater trochanteric pelvic impingement (GTPI)? How does one diagnose and treat this condition?

Trousdale: Greater trochanteric pelvic impingement can occur in patients who have a markedly proximally located greater trochanter. Lots of conditions can lead to this. Perthes patients commonly have this. The patient with a congenital coxa vara can have this. Treatment of GTPI is nonsurgical initially and if the nonsurgical treatments have failed, a trochanteric advancement and if needed, relative neck lengthening is prudent. I would combine this with an open surgical dislocation to deal with any intra-articular pathology that is present.

Larson: Greater trochanteric pelvic impingement is classically seen in Legg-Calve-Perthes disease with a prominent GT. Hip abduction can lead to impingement of the GT against the pelvis described as the “gear stick” sign. It is also uncommonly seen outside the setting of Perthes and typically presents as limited hip ROM often with underwhelming plain radiographic deformity. When hip ROM is limited more than expected based on radiographs and an intra-articular anesthetic injection fails to provide temporary pain relief, GTPI should be suspected.

Femoral version can play a significant role as relative femoral retroversion can lead to anterior impingement/posterior instability, whereas increased femoral anteversion can lead to posterior impingement/anterior instability. Ultrasound evaluation and/or dynamic software analysis can further support the diagnosis, but ultimately the diagnosis is confirmed at the time of surgery. Because of the challenges in diagnosing this entity preoperatively, I believe a surgical dislocation and greater trochanteric transfer procedure is the procedure of choice for this uncommon problem.

Matsuda: What is lateral cephalic impingement?

Martin: Lateral cephalic impingement as described by Matsuda and colleagues is a type of femoral head deformity from a malunited femoral head fracture inducing a secondary lateral femoroacetabular impingement. This area is accessible arthroscopically as is most of the acetabulum and femoral head, enabling malunion takedown, reduction, bone grafting and osteosynthesis using completely arthroscopic techniques. There is an expanding role for the utilization of arthroscopy in the management of femoral head and select acetabular fractures and its future appears promising.

For more information:

Christopher M. Larson, MD, can be reached at Minnesota Orthopedic Sports Medicine Institute at Twin Cities Orthopedics, 4010 West 65th St., Edina, MN 55435; email: clarson@tcomn.com.

Hal D. Martin, DO, can be reached at The Hip Preservation Center, 3900 Junius St., Suite 705, Dallas, TX 75246; email: hal.martin@baylorhealth.edu.

Dean K. Matsuda, MD, can be reached at DISC Sports & Spine Center, 13160 Mindanao Way, Suite 325, Marina del Rey, CA 90292; email: dmatsuda@discmdgroup.com.

Robert T. Trousdale, MD, can be reached at Mayo Clinic, 200 First St. SW E14B, Rochester, MN 55905; email: trousdale.robert@mayo.edu.

Disclosures: Larson reports he is a consultant for Smith & Nephew and A3 Surgical and has stock options in A3 Surgical. Martin reports he is a consultant for Smith & Nephew and Pivot Medical. Matsuda reports he receives royalties from ArthroCare and Smith & Nephew and is a paid consultant for Biomet. Trousdale reports he has relationships with DePuy, Wright Medical, Mako and Mayo Clinical.