Distal Femoral Neck Research Articles

Arthroscopic Decompression of the Anterior Inferior Iliac Spine.

Pathologic contact between the femoral neck and anterior inferior iliac spine (AIIS or subspine) often occurs concomitantly with femoroacetabular impingement, contributing to hip pain and dysfunction1-4. We perform arthroscopic AIIS decompression to alleviate this source of extra-articular impingement and eliminate a potential cause of persistent pain following primary hip arthroscopy5-7. After identifying abnormal AIIS morphology on preoperative false-profile radiographs and/or 3D computed tomography, we utilize a beaver blade to make a small incision in the proximal capsule and rectus femoris tendon. This peri-capsulotomy window grants access to the subspine region. We then shuttle an arthroscopic burr into place within this window and begin debriding the subspine deformity under direct visualization. Fluoroscopy is utilized intraoperatively to ensure adequate resection, using intraoperative false-profile views achieved by canting the C-arm approximately 40°. Resection is considered adequate when the AIIS deformity is no longer readily apparent on false-profile views and when intraoperative range-of-motion testing confirms no further impingement with hip hyperflexion. Femoroacetabular impingement can be treated nonoperatively with use of physical therapy and activity modification8; however, outcomes following nonoperative treatment are inferior to those following hip arthroscopy, according to various studies9-12. There are no known alternative treatments specific to subspine impingement. As patients with subspine deformities progress through hip flexion, the femoral neck collides with the AIIS, limiting range of motion. As such, subspine deformities have been shown to be more common in dancers and other high-flexion athletes13,14. Additionally, studies have demonstrated that low femoral version of <5° is associated with increased contact between the distal femoral neck and the AIIS. This pathologic contact can occur even in the absence of an obvious subspine deformity15. In both of these patient populations, surgeons should have a high suspicion for subspine impingement, and a subspine decompression should be performed during hip arthroscopy in order to maximize patient outcomes. This is a safe procedure that, if performed when indicated, can improve outcomes following primary hip arthroscopy. A recent systematic review found a pooled complication risk of 1.1%, a pooled revision risk of 1.0%, and significant postoperative improvements in patient-reported outcome measures16. Suspect subspine impingement in high-flexion athletes and patients with low femoral version, even in the absence of an obvious deformity.Ensure adequate visualization of the entire subspine deformity by creating a pericapsular window.Confirm thorough resection with use of fluoroscopic imaging intraoperatively, including false-profile views demonstrating absent subspine deformity. FAI = femoroacetabular impingementAP = anteroposterior, refers to the technique used to obtain one of the pelvic radiographs3D CT = three-dimensional computed tomographyLCEA = lateral center-edge angle, a measurement used to quantify severity of hip dysplasiaOR = operating roomAlpha = alpha angle, a measurement used to measure femoral head-neck offset and assess the severity of a cam deformityIc = iliocapsularisRFd = direct head of rectus femorisRFr = reflected head of rectus femorisCap = hip capsuleGMi = gluteus minimusmHHS = modified Harris Hip ScoreHOS-ADL = Hip Outcome Score - Activities of Daily LivingHOS-SSS = Hip Outcome Score - Sports Specific Subscale.

Prevalence of Anterior Inferior Iliac Spine Dysmorphism and Development of a Novel Classification System: An Anatomic Study of 1,797 Cadaveric Specimens.

Purpose: Subspine impingement occurs due to a morphologically abnormal anterior inferior iliac spine (AIIS), capable of causing impingement against the distal femoral neck. The purpose of this investigation was to determine the prevalence of AIIS dysmorphism based on specimen sex, race, and age, while introducing a novel anatomic-based classification system.Methods: A total of 1,797 adult cadaveric specimens (n = 3,594 hemipelvises) were analyzed. AIIS with the potential for subspine impingement (SSI) was recorded in each specimen by two independent authors. Specimens with AIIS dysmorphism were then reexamined to determine SSI subtype using a novel descriptive anatomic classification system.Results: AIIS dysmorphism was present in 6.4% (n = 115 of 1,797 specimens) of specimens and 5.2% (n = 186 of 3,594) of hemipelvises. Dysmorphism was significantly more common in male specimens (p = 0.04) and African–American specimens (p = 0.04). No significant overall difference in prevalence was appreciated based on specimen age (p = 0.89). Subtype classification found that 67% of hemipelvises possessed a columnar type AIIS, 30% were bulbous and 3% hook type. Males possessed a significantly higher prevalence of columnar type AIIS dysmorphism (p < 0.001). No significant overall differences in anatomic classification were appreciated based on race (p = 0.12) or when analyzed based on age (p = 0.34).Conclusion: AIIS dysmorphism was present in 6.4% of the 1,797 cadaveric specimens evaluated. African-American and male specimens possessed significantly higher prevalence of AIIS dysmorphism, with no significant difference based on specimen age. Columnar type AIIS dysmorphism was most common. Anatomic classification was not significantly different based on specimen race or age.Level of Evidence: Case Series, Level IV.

MRI Assessment of Subspine Impingement: Features beyond the Anterior Inferior Iliac Spine Morphology.

Background The MRI manifestations of subspine impingement (SSI) other than morphologic features of anterior inferior iliac spine (AIIS) have not been extensively explored and validated. Purpose To determine the MRI findings associated with SSI, including AIIS morphologic features, femoral distal cam, and associated soft-tissue injuries. Materials and Methods This is a retrospective study of symptomatic patients who underwent arthroscopic treatment for femoroacetabular impingement between December 2014 and March 2017, with preoperative MRI within 6 months before surgery. The SSI group included patients with clinical and intraoperative findings of SSI; the remaining patients comprised the non-SSI group. Preoperative MRI findings were independently assessed by two radiologists who were blinded to clinical information. Interreader agreement was assessed, and multivariable logistic regression was also used. Results A total of 62 patients (mean age ± standard deviation, 42.1 years ± 11.9; 38 women) were included. SSI was diagnosed in 20 of the 62 patients (32%) (mean age, 43 years ± 12); 42 patients (68%) did not have SSI (mean age, 41 years ± 10). Reader 1 detected distal cam in 16 of the 20 patients with SSI (80%) and eight of the 42 patients without SSI (19%), and reader 2 detected distal cam in 15 of the 20 patients with SSI (75%) and eight of the 42 patients without SSI (19%) (P < .001 for both). Reader 1 detected signs of impingement on the distal femoral neck (IDFN) in 18 of the 20 patients with SSI (90%) and seven of the 42 patients without SSI (16%), and reader 2 detected signs of IDFN in 13 of the 20 patients with SSI (65%) and nine of the 42 patients without SSI (21%) (P < .001 and P = .001, respectively). Reader 1 detected superior capsular edema in 15 of 20 patients with SSI (75%) and three of 42 patients without SSI (7%), and reader 2 detected superior capsular edema in 17 of 20 patients with SSI (85%) and 22 of 42 patients without SSI (52%) (P < .001 and P = .02, respectively). Distal cam was a predictor of SSI after adjustment for IDFN. Interreader agreement was substantial for distal cam (κ = 0.80) and moderate for IDFN (κ = 0.50). Conclusion Soft-tissue injuries and osseous findings other than morphologic features of the anterior inferior iliac spine were associated with subspine impingement. © RSNA, 2019 See also the editorial by Guermazi in this issue.

Extra-articular Hip Impingement: Anterior Inferior Iliac Spine/Subspine Impingement, Ischiofemoral, and Anterior and Lateral Greater Trochanteric-Pelvic Impingement

AbstractAlthough femoroacetabular impingement (FAI) is traditionally considered an intra-articular phenomenon, the result of abutment between the femoral head and/or neck and the acetabular rim, there are unique and relatively uncommon patterns of pathologic extra-articular hip impingement that can mimic the clinical presentation and clinical findings of traditional FAI. Anterior inferior iliac spine (AIIS) or “subspine” impingement may occur as a consequence of an abnormally anterior or distal prominence of the AIIS that may be developmental, posttraumatic, or the result of high range of motion (ROM) activities. This type of impingement can crush the capsule, labrum, and rectus femoris between the AIIS and distal femoral neck in straight hip flexion. Greater trochanteric/pelvic impingement is quite complex and can be further divided into three unique anatomic patterns. Anterior greater trochanteric–pelvic impingement is the result of impingement between the anterior hip soft tissue structures or the anterior facet/greater trochanter and anterolateral rim/lateral AIIS and pelvis when the hip is flexed, internally rotated, and abducted. This can occur in association with a prominent greater trochanter, short femoral neck, relative femoral retrotorsion, and high ROM activities. Lateral greater trochanteric–pelvic impingement is the result of impingement between an abnormally prominent or a high riding greater trochanter with a short femoral neck and the lateral pelvis when the hip is abducted. This type of impingement is characteristic of a Perthes-like hip and, in extreme cases, can be associated with severe leg length discrepancy (and abductor muscle dysfunction). Posterior greater trochanteric–pelvic/ischiofemoral impingement is the result of impingement of the quadratus femoris and/or proximal hamstring tendons between the lesser trochanter or posterior proximal femur and intertrochanteric line and the ischial tuberosity when the hip is extended and external rotated (ER). This can occur in association with deformities of the ischial tuberosity caused by prior avulsion fractures, lesser trochanteric overgrowth, extreme coxa valga, femoral antetorsion, complex proximal femoral developmental deformities, and activities requiring high degrees of extension and external rotation. A thorough understanding of these unique patterns of impingement, their clinical presentations, and complex treatment options can help in optimizing outcomes and minimizing complications in this very challenging patient population.

Modified neck-lengthening osteotomy after Morscher in children and adolescents

Growth disorders (e. g. caused by congenital hip dislocation, Perthes disease or bacterial coxitis) often lead to an infantile deformity of the proximal femur with ashortened femoral neck and displaced grater trochanter. In 1988, Morscher and Buess described a femoral neck lenghtening osteotomy for treatment of adults. For the first time, we show amodification of this osteotomy for children and adolescents with alocking plate system. The aim is to restore the normal anatomy of the femoral neck and biomechanics of the proximal femur. All symptomatic deformities of the proximal femur with ashortened femoral neck and aproximal displacement of the greater trochanter. Bacterial coxitis within the last two years; elevated infections parameters. Acetabular dysplasia with alack of femoral head containment. Two osteotomies: one at the level of the greater trochanter to transfer it. The second osteotomy at the level of the distal femoral neck. Stabilization with alocking plate system (LCP Pediatric Hip Plate 130°, Synthes, Oberdorf, Switzerland). Full weight bearing to abody weight of 55 kg; partial weight bearing with abody weight >55 kg for 6weeks. No intraoperative or postoperative complications were observed in 5 female patients (mean age 11.67 years). After afollow-up of 6-12weeks, none of the patients presented aTrendelenburg's sign. After 3-6months, full range of motion was possible.

Posterolateral Acetabuloplasty and Distal Femoral Neckplasty, Labral Repair, and Capsular Plication for Hip Reverse Contre-Coupe Lesion

This article describes the arthroscopic approach and management of a “reverse contre-coup” injury to the hip labrum. The injury occurs in the setting of posterolateral acetabular rim over-coverage impinging on the distal femoral neck in extension causing the femoral head to lever out anteriorly against the labrum. Ligamentous laxity and associated loss of anterior capsular restraint allow increased femoral head translation, adding further insult to the anterior labrum. The arthroscopic approach entails not only a labral repair with correction of the osseous conflict but also restoration of soft-tissue stability to minimize anterior femoral translation.

Femoral Neck Stress Fracture

The patient was a 19-year-old woman who recently completed a military basic training program. She was evaluated by a physical therapist in a direct-access capacity for a chief complaint of anterior right hip pain that limited her ability to run. Due to the limited sensitivity of radiographs, magnetic resonance imaging of the right hip was obtained, which revealed a stress fracture of the right distal femoral neck.J Orthop Sports Phys Ther 2013;43(4):275. doi:10.2519/jospt.2013.0407.

The Gotfried (Nonanatomic, Closed) Reduction of Unstable Subcapital Femoral Fractures

A nonanatomic reduction of displaced—unstable subcapital femoral fractures has been described. The rationale of this approach is based on biomechanical consideration. Definitions used in this method include: negative buttress—in which the lower medial edge of the proximal fracture part (femoral neck and head) is protruding medially to the upper medial edge of the distal femoral neck part; positive buttress—in which the upper medial edge of the distal femoral neck part is protruding medially to the distal medial edge of the proximal fracture part. Because observations have shown that negative buttress is associated with a higher failure rate of reduction, negative buttress should be avoided. Negative buttress allows easier displacement of the reduced femoral head into the varus; positive buttress acts in the opposite way. Hence, the goal of the Gotfried reduction is to create a positive buttress reduction while at the same time reduce the fracture in the valgus. With the patient positioned on a fracture table, the procedure includes 3 stages: (1) desimpaction; (2) reduction; and (3) reconstruction. The author uses this technique when preservation of the femoral head, after subcapital fractures, is desired.

Neck-Preserving Femoral Stems

Surgeons undertaking total hip arthroplasty (THA) routinely perform a distal femoral neck resection. It has been argued that retaining the femoral neck during THA can provide mechanical and biological advantages. The objectives of this study were to review: (1) the current evidence on the advantages of femoral neck preservation during THA and (2) the clinical and radiological outcome of neck-preserving femoral stems. A search of the English-language literature on neck-preserving THA and on the individual neck-preserving implants was performed using PubMed, Ovid SP and Science Direct. Studies have indicated that neck preservation offers superior tri-planar implant stability and allows more accurate restoration of the hip geometry and biomechanics. The trend towards tissue sparing surgery has contributed to the development of bone-conserving short-stem implants that offer variable levels of neck preservation. Despite an initial learning curve, these implants have generated promising early clinical results, with low revision rates and high outcome scores. However, radiological evaluation of some neck-preserving implants has detected a characteristic pattern of proximal femoral bone loss with distal cortical hypertrophy. The long-term implications of this finding are not yet known. Preserving the femoral neck during THA has biomechanical advantages. However, long-term outcome data are needed on neck-preserving femoral stems to evaluate on-going bone remodelling and assess implant performance and survival.

Importance of the integrity of trabecular bone to the relationship between load and deformation of rat femora: an optical metrology study

Bone is a composite hierarchical structure composed of a cortical shell and inner trabecular tissue. One of the most basic questions in whole-bone function is the relative contributions of cortical and trabecular bone tissues to the loaded whole bone. In this study, the manner in which the cortical surfaces of an intact proximal rat femur deform under load is compared to the same femur after some of the trabecular bone in the distal femoral neck was removed. The surface displacements were measured by electronic speckle pattern interferometry (ESPI) and the extent of trabecular bone removed was determined by high resolution micro-CT scanning. The results show that after damaging the trabecular bone tissue in the distal femoral neck, the manner in which compressive loads are transformed to other regions of the femoral neck changed. The whole bone behaved in a ‘stiffer’ manner. This demonstrates the importance of connectivity of the trabeculae and that beyond a certain threshold of damage the normal load-transferring mechanism is impaired. Since these experiments were carried out in a non-contact non-destructive manner in a wet environment and the rat femur was loaded in a close-to physiological manner, we postulate that our results have a direct relevance to the in vivo biomechanical behavior of the femoral neck.