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Surgical Correction of Healed Legg-Calve-Perthes Deformity
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Surgical Correction of Healed Legg-Calve-Perthes Deformity Malcolm Dombrowski MD Orthopaedic Surgery Resident , Michael McClincy MD Associate Professor PII: DOI: Reference:
S1048-6666(20)30009-4 https://doi.org/10.1016/j.oto.2020.100784 YOTOR 100784
To appear in:
Operative Techniques in Orthopaedics
Please cite this article as: Malcolm Dombrowski MD Orthopaedic Surgery Resident , Michael McClincy MD Associate Professor , Surgical Correction of Healed Legg-Calve-Perthes Deformity, Operative Techniques in Orthopaedics (2020), doi: https://doi.org/10.1016/j.oto.2020.100784
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Inc.
Surgical Correction of Healed Legg-Calve-Perthes Deformity
Malcolm Dombrowski, MD, Orthopaedic Surgery Resident1 Michael McClincy, MD, Associate Professor1 1Department
of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA
Manuscript prepared for Operative Techniques in Orthopaedics Corresponding Author: Michael McClincy, MD UPMC Children’s Hospital of Pittsburgh 4401 Penn Avenue Pittsburgh, PA 15224 (412) 692-3257 [email protected] Abstract Healed Legg-Calve-Perthes disease (LCPD) is a complex problem to manage for the treating orthopaedic surgeon. LCPD begins as a pediatric disorder characterized osteonecrosis of the femoral head. Once the initial osteonecrotic insult resolves, the patient is left with a complex deformity of the proximal femur and acetabulum leading to symptomatic femoroacetabular impingement (FAI) and, potentially, hip instability. Throughout this review we will highlight the relevant patient evaluation, radiographic parameters, and surgical algorithm to aid in the management of this difficult problem. Treatment of this condition is best achieved through a surgical dislocation approach to thoroughly address the intra- and extra-articular sources of femoroacetabular impingment, with the occasional patient requiring a redirective acetabular osteotomy to further improve morphology and function.
Introduction Legg-Calve-Perthes disease (LCPD) is a pediatric disorder characterized by osteonecrosis of the femoral head. The osteonecrotic lesion ultimately heals, but residual deformity to the proximal femur and acetabulum can continue to cause hip pain and dysfunction after the healing process. Previous reports have noted anywhere between 30-50% of individuals affected by LCPD to have residual hip symptoms which persist into adulthood.(1–3) The resultant deformities of the hip can lead to the pathologic processes of femoroacetabular impingement (FAI), hip instability, or a combination of both pathologies. The residual effects of LCPD are highly variable, but generally speaking the longitudinal prognosis of the hip can be directly linked to the overall level of femoral head sphericity and joint congruence.(4–6) To understand the morphologic consequences of LCPD, it is imperative to understand the pathologic changes that occur at the start of the disease’s course. Early LCPD is characterized by focal osteonecrosis of the femoral epiphysis. This process entails damage to the epiphyseal bone as well as the proximal physis. Epiphyseal damage may result in femoral head asphericity, coxa magna, or coxa plana after healing, while damage to the proximal physis may result in coxa breva and a high-riding greater trochanter (Figure 1). On the acetabular side, retroversion is commonly encountered in LCPD patients, and acetabular remodeling in response to significant proximal femoral deformity may lead to an adaptive form of acetabular dysplasia.(7) Successful treatment of deformity following LCPD requires an ability to accurately identify and subsequently improve the varied pathomorphology encountered. The goal of treatment is a stable, concentrically reduced joint with an optimized range of motion. Patient Evaluation History Symptoms caused by the morphologic abnormalities encountered in healed LCPD deformities reflect those encountered in the idiopathic cases of FAI and dysplasia.
Classic FAI is characterized by the abnormal, repetitive contact of the anterior femoral head and neck with the anterior acetabulum. In the healed LCPD hip, this impingement can result from morphologic changes on either the proximal femur or acetabulum. This abnormal contact leads to progressive damage to the acetabular cartilage, acetabular labrum, or both.(8) Patients with FAI tend to have anterior groin pain and pain in the “c-sign” region of the hip, which is aggravated by physical activity, prolonged sitting, and positions of flexion and internal rotation. Stiffness or loss of motion is also quite common and can at times become symptomatic prior to the onset of pain. Extra-articular FAI, involving contact between the trochanters and the pelvis, can also be seen. It presents as posterolateral hip pain with extension activities when localized to the greater trochanter and posterior groin pain with extension activities when localized to the lesser trochanter. Instability symptoms typically manifest during upright activities such as walking or running. Pain in these cases typically localizes to the anterior groin. Complaints of muscular fatigue and pain along the psoas and tensor fascia latae may be subtle indications of instability in these patients. Abductor fatigue and a perceived limp can be related to instability but also may be a product of the high-riding greater trochanter and associated inefficiency of the gluteal musculature. Symptoms of locking at “catching” of the hip joint with activity may be indicative of articular pathology such as labral tears, cartilage flaps, or loose bodies. Imaging Initial imaging of patients with healed LCPD deformity should provide a thorough analysis of both the proximal femoral and acetabular morphology. Routine radiographs should include a standing AP pelvis, lateral view of the proximal femur (45° Dunn recommended), and a false profile view of the acetabulum. Measurements of proximal femoral deformity (alpha angles, head-neck offset ratios) should be performed on both AP and lateral views, and coxa magna and plana should be scrutinized on the AP pelvis. The position of the greater trochanter with
respect to the femoral head, as well as the femoral neck-shaft axis should be measured on the AP pelvis film. On the acetabular side, measurements of acetabular coverage (lateral center edge angle, Tonnis roof angle, anterior center edge angle, anterior/posterior wall indices) should be measured. Markers of acetabular retroversion, such as the crossover sign, posterior wall sign, and prominent ischial spine sign, should be observed. Careful attention should be paid to the markers of acetabular retroversion as LCPD patients occasionally present with a flexion contracture of the hip, which may rotate the pelvis and limit applicability of the retroversion markers. Due to the often-significant deformity present in these patients, we also recommend routine cross-sectional imaging in this patient group. CT and MRI are both reasonable imaging modalities for this purpose. Both provide improved means to measure the acetabular and femoral version in these patients, both of which are important to identify in these patients. CT has the added benefit of generating 3dimensional reconstructions that can be invaluable in the appreciation of complex deformities, but it comes at the cost of added radiation to the patient. MRI has the benefit of providing soft tissue details and thorough evaluation of the femoral headneck junction through radial imaging, however it lacks the bony detail provided by CT and cannot be easily converted to a 3-dimensional image. Clinical Case A 21 year old male presented for evaluation of a continually painful right hip. His history was remarkable for a varus proximal femoral osteotomy at the age of 6 for Pillar B/C hip which failed conservative treatment. He subsequently underwent a valgus proximal femoral osteotomy at the age of 15 for pain and impingement. At the time of our evaluation, he still had significant impingement related symptoms which made seated activities difficult. He was noted to have hip flexion to 80 degrees with >5 degrees of obligate external rotation in this position. He had intraarticular impingement signs on exam as well as posterior impingement features
with external rotation applied in either hip flexion or extension. His pre-operative radiographs and CT scan are shown in Figure 2 A-C. Pathomorphology of Healed LCPD Following resolution of the acute phase of LCPD, patients can present with a variety of morphological pathology on both the proximal femoral and acetabular sides of the hip joint. Femoral Pathomorphologic Subtypes -Intraarticular impingement: Cam-type deformity Classically, cam-type deformity of the proximal femur develops due to an overgrowth of the inferior and antero-lateral aspects of the femoral head. This overgrowth pattern is the result of physeal disruption during the active phases of osteonecrotic insult. In these individuals, the “true” femoral head lies in a position superior and posteromedial and articulates with the acetabulum.(9) In these cases, the true femoral head articulates with the acetabulum in upright activities, however in flexion, the aspherical aspect of the femoral head engages within the anterolateral acetabulum. Other sites of potential asphericity in response to LCPD include medial or posteroinferior osseous spurs which impinge on the acetabular fossa or posteroinferior acetabulum, respectively. The cam-type impingement leads to shear forces on the acetabular cartilage and the chondrolabral junction and predisposes to chondrolabral junction tears and cartilage delamination.(8) Relative femoral head retroversion is a variant of cam-type deformity and arises in certain cases of LCPD where there is a significant discrepancy in the positioning between the anterolateral “false” femoral head and the posteromedial “true” femoral head. This discrepant position places the articulating posteromedial head out of line with the femoral neck into a position of relative retroversion.(9–11) Patients with this deformity have notable trouble with hip flexion without significant compensatory external rotation.(12)
Treatment: With cam-type deformities of the proximal femur, our suggested treatment method is a femoral head/neck osteoplasty through a surgical dislocation approach, which affords circumferential access to the femoral head/neck and acetabulum. When considering the degree of osseous resection in cases of healed LCPD deformity, the use of Mose spheres intraoperatively, along with frequent dynamic examinations, are used to determine the optimal degree of resection. In cases of relative femoral retroversion, where femoral osteoplasty does not completely resolve the motion restrictions, an intertrochanteric flexion/internal rotation osteotomy can be performed to improve the alignment of the articulating femoral head with the remainder of the femur.(13) -Intraarticular impingement: Pincer-type deformity Pincer-type impingement of the proximal femur is a relatively rare condition, with the predominance of pincer lesions arising from the acetabulum. In LCPD these deformities arise in the same manner as cam-type deformities and are characterized by marked asphericity of the native femoral head. Unlike cam-type deformities, the pincer-type deformities are misshapen to a degree that prevents the involved portions of the femoral head from entering the acetabulum. Pincer deformities typically result in significant labral injury and detatchment due to the mechanical compression of this struction between the acetabular rim and proximal femur.(8) Significant degrees of motion restriction can also lead to impingement cysts on the femoral neck and contre-coup injuries to the posterior acetabulum due to impingement-driven instability.(14–16) (12-14) Coxa magna and coxa plana are radiographic markers suggestive of this dramatic deformity.(17,18) Von Rosen (abduction – internal rotation) views can help identify this morphology preoperatively, but intraoperative inspection of motion restriction is the most reliable means of diagnosis. In a select group of patients with a combination of coxa magna and plana deformities, a central area of necrotic subchondral bone persists in the femoral head, and the combined deformities results in a hinge type joint with frontal plane motion but limited abduction (ie. hinged abduction).
Treatment: With pincer-type proximal femoral deformity, our treatment protocol starts with a surgical hip dislocation. Upon accessing the femoroacetabular articulation, a careful inspection of motion restriction and regions of impingement is imperative. In cases where the femoral head cartilage and associated subchondral bone appear intact, an osteoplasty should be performed, again using Mose spheres and dynamic examinations as the guides for performing the bony resection. A flexion intertrochanteric osteotomy can be added to reorient the femoral head within the acetabulum in cases with residual impingement following thorough osteoplasty. -Extra-articular impingement: Greater trochanter Epiphyseal disruption during LCPD frequently effects the longitudinal growth from the proximal femoral physis while the greater trochanteric apophysis and femoral neck appositional growth continue on normal trajectories.(19) The resultant deformity is a short and wide femoral neck, termed coxa brevis, and a high riding greater trochanter. It is important to note that healed LCPD deformity does not typically present with a varus deformity unless a prior containment osteotomy was performed. The clinical manifestations of this deformity are extra-articular impingement, specifically with hip abduction in a neutral or extended position with external rotation, causing the greater trochanter to hit the ilium.(20) Abductor weakness and associated limp is also common due to the position of the greater trochanter. Treatment: Goals of treatment are to resolve the extra-articular impingement by the greater trochanter and improve the lever arm function for the gluteal musculature. Again through a surgical dislocation approach as described previously, a relative femoral neck lengthening procedure can be performed by resection of the stable trochanteric base after digastric osteotomy, followed by distalization of the mobile trochanteric segment after completion of intra-articular work (Figure 3).(21) The
trochanteric fragment is ideally translated until its tip lies at the level of the center of the femoral head, where it is fixated with two or three 4.5mm screws. Acetabular Pathomorphologic Subtypes Acetabular dysplasia and retroversion in LCPD are reactive conditions related to the repetitive collision of the proximal femur and acetabulum that results in premature closure of the triradiate cartilage.(20,22) Acetabular abnormalities are seen more commonly in cases involving significant proximal femoral patho-morphology.(7,22) The degree of acetabular dysplasia or retroversion and hip instability must be appreciated prior to surgery but also must be reassessed after correction of femoral-sided deformity. Treatment: The majority of patients presenting for surgical correction of LCPD deformity will have reached skeletal maturity. As such, our recommended acetabular reorientation procedure in patients with instability findings after proximal femoral reconstruction is the Bernese periacetabular osteotomy (PAO). One technical consideration during PAO in the treatment of acetabular dysplasia in LCPD is that over-coverage and iatrogenic impingement should be avoided. A “conservative” acetabular orientation correction is recommended in this patient group. As the proximal femur remains imperfect in LCPD, less acetabular constraint can be advantageous and iatrogenic impingement catastrophic. Mixed Pathomorphology Types The vast majority of patients with healed LCPD deformities will present with hips with a wide variety of both proximal femoral and acetabular pathomorphologies. Our proposed flowchart for management of healed LCPD deformity is shown in Figure 4. The proximal femoral changes ubiquitously make patients susceptible to femoroacetabular impingement and the resultant joint damage and dysfunction. The proximal femoral deformity should be addressed first in all patients with healed
LCPD. Our typical approach involves a surgical hip dislocation with extensive femoral osteochondroplasty for intra-articular impingement followed by a relative femoral neck lengthening in cases with extra-articular impingement. In cases with significant deformity of the proximal femur that cannot be addressed by osteochondroplasty alone, we perform a redirecting intertrochanteric osteotomy to better orient the articular femoral head within the acetabulum. After complete correction of proximal femoral morphology, we turn our attention to the acetabular side. In cases with residual impingement due to an acetabular pincer deformity, we perform a focal acetabuloplasty or acetabular reorientation osteotomy based on the global acetabular morphology. In cases with resultant instability, we perform a PAO to reorient the acetabulum into a position to optimize stability while avoiding impingement. Clinical Case Our patient underwent a surgical dislocation of the right hip with an extensive osteoplasty of the proximal femur with a large region of bone resection from the anterior and superior aspect of the femoral head down to the base of the anterior greater trochanter. A relative neck lengthening was also performed to facilitate distalization of the greater trochanter and improve tensioning of this abductor musculature. His post-operative radiographs are seen in Figure 5. He had a substantial improvement in function and range of motion after surgery. At 1 year from surgery, the patient was regularly exercising including weight training and cycling with little pain complaints or functional limitations. Outcomes The modern approach to healed LCPD deformity, as described above, has been described in small case series with mid-term follow-up (3-4 years).(23–27) The majority of patients underwent femoral osteoplasty and relative neck lengthening procedures (>60%), while only a fraction required proximal femoral osteotomies (~25%) or periacetabular osteotomies (~10%). The majority (75%) of patients
showed improvement in hip function and pain at final follow-up, with 40% reporting no hip pain. Nearly 10% of patients failed their reconstructive procedure and went on to total hip arthroplasty. Conclusion Residual deformity following healed Legg-Calve-Perthes disease is a cause of hip pain and dysfunction in young, active people. Treatment of this condition is best achieved through a surgical dislocation approach to thoroughly address the intraand extra-articular sources of femoroacetabular impingment. In certain cases, periacetabular osteotomy may also be indicated in cases of hip instability after correction of proximal femoral deformity.
References: 1. Engelhardt P. [Late prognosis of Perthes’ disease: which factors determine arthritis risk?]. Z Orthop Ihre Grenzgeb. 1985 Apr;123(2):168–81. 2. Lecuire F. The long-term outcome of primary osteochondritis of the hip (LeggCalve-Perthes’ disease). J Bone Jt Surg Br. 2002 Jul;84(5):636–40. 3. McAndrew MP, Weinstein SL. A long-term follow-up of Legg-Calve-Perthes disease. J Bone Jt Surg Am. 1984 Jul;66(6):860–9. 4. Mose K, Hjorth L, Ulfeldt M, Christensen ER, Jensen A. Legg Calve Perthes disease. The late occurence of coxarthrosis. Acta Orthop Scand Suppl. 1977;169:1–39. 5. Stulberg SD, Cooperman DR, Wallensten R. The natural history of Legg-CalvePerthes disease. J Bone Jt Surg Am. 1981 Sep;63(7):1095–108. 6. Weinstein SL. Legg-Calve-Perthes disease: results of long-term follow-up. Hip. 1985;28–37. 7. Ezoe M, Naito M, Inoue T. The prevalence of acetabular retroversion among various disorders of the hip. J Bone Jt Surg Am. 2006 Feb;88(2):372–9. 8. Ganz R, Parvizi J, Beck M, Leunig M, Notzli H, Siebenrock KA. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res. 2003 Dec;(417):112–20. 9. Kim HT, Wenger DR. “Functional retroversion” of the femoral head in LeggCalve-Perthes disease and epiphyseal dysplasia: analysis of head-neck deformity and its effect on limb position using three-dimensional computed tomography. J Pediatr Orthop. 1997 Apr;17(2):240–6. 10. Katz JF. Femoral torsion in Legg-Calve-Perthes disease. J Bone Jt Surg Am. 1968 Apr;50(3):473–5. 11. Upadhyay SS, Burwell RG, Moulton A. Femoral anteversion in Perthes’ disease with observations on irritable hips. Application of a new method using ultrasound. Clin Orthop Relat Res. 1986 Aug;(209):70–6. 12. Yoo WJ, Choi IH, Cho TJ, Chung CY, Park MS, Lee DY. Out-toeing and in-toeing in patients with Perthes disease: role of the femoral hump. J Pediatr Orthop. 2008 Nov;28(7):717–22. 13. Kim HT, Wenger DR. Surgical correction of “functional retroversion” and “functional coxa vara” in late Legg-Calve-Perthes disease and epiphyseal dysplasia: correction of deformity defined by new imaging modalities. J Pediatr Orthop. 1997 Apr;17(2):247–54.
14. Steppacher SD, Albers CE, Siebenrock KA, Tannast M, Ganz R. Femoroacetabular impingement predisposes to traumatic posterior hip dislocation. Clin Orthop Relat Res. 2013 Jun;471(6):1937–43. 15. Hoffinger SA, Rab GT, Salamon PB. “Metaphyseal” cysts in Legg-Calve-Perthes’ disease. J Pediatr Orthop. 1991 Jun;11(3):301–6. 16. Leunig M, Beck M, Kalhor M, Kim YJ, Werlen S, Ganz R. Fibrocystic changes at anterosuperior femoral neck: prevalence in hips with femoroacetabular impingement. Radiology. 2005 Jul;236(1):237–46. 17. Keret D, Harrison MH, Clarke NM, Hall DJ. Coxa plana--the fate of the physis. J Bone Jt Surg Am. 1984 Jul;66(6):870–7. 18. Rowe SM, Jung ST, Cheon SY, Choi J, Kang KD, Kim KH. Outcome of cheilectomy in Legg-Calve-Perthes disease: minimum 25-year follow-up of five patients. J Pediatr Orthop. 2006 Apr;26(2):204–10. 19. Robichon J, Desjardins JP, Koch M, Hooper CE. The femoral neck in Legg-Perthes’ disease. Its relationship to epiphysial change and its importance in early prognosis. J Bone Jt Surg Br. 1974 Feb;56(1):62–8. 20. Joseph B. Morphological changes in the acetabulum in Perthes’ disease. J Bone Jt Surg Br. 1989 Nov;71(5):756–63. 21. A Systematic Approach to Analyse the Sequelae of LCPD - Moritz Tannast, Neil MacIntyre, Simon D. Steppacher, Harish S. Hosalkar, Reinhold Ganz, Klaus A. Siebenrock, 2013 [Internet]. [cited 2019 Dec 12]. Available from: https://journals.sagepub.com/doi/abs/10.5301/hipint.5000071 22. Sankar WN, Flynn JM. The development of acetabular retroversion in children with Legg-Calve-Perthes disease. J Pediatr Orthop. 2008 Jun;28(4):440–3. 23. Anderson LA, Erickson JA, Severson EP, Peters CL. Sequelae of Perthes disease: treatment with surgical hip dislocation and relative femoral neck lengthening. J Pediatr Orthop. 2010 Dec;30(8):758–66. 24. Albers C, Steppacher S, Ganz R, Siebenrock K, Tannast M. Joint-preserving Surgery Improves Pain, Range of Motion, and Abductor Strength After LeggCalvé-Perthes Disease. Clin Orthop. 2012 Sep;470(9):2450–61. 25. Rebello G, Spencer S, Millis MB, Kim Y-J. Surgical dislocation in the management of pediatric and adolescent hip deformity. Clin Orthop. 2009 Mar;467(3):724– 31.
26. Shore B, Novais E, Millis M, Kim Y-J. Low Early Failure Rates Using a Surgical Dislocation Approach in Healed Legg-Calvé-Perthes Disease. Clin Orthop. 2012 Sep;470(9):2441–9. 27. Eijer H, Berg RP, Haverkamp D, Pecasse GA. Hip deformity in symptomatic adult Perthes’ disease. Acta Orthop Belg. 2006 Dec;72(6):683–92.
Figure Captions:
Figure 1: AP radiograph of a post-LCPD hip deformity with a markedly aspherical femoral head and high-riding greater trochanter.
Figure 2: Preoperative radiographs: (A) AP Pelvis showing an aspherical femoral head (sagging rope sign) and a high riding greater trochanter. The acetabulum has developed some undercoverage, likely from the femoral deformity; (B) 45 degree Dunn lateral showing marked anterosuperior asphericity of the femoral head-neck junction with loss of offset; (C) 3-D CT reconstructions showing the femoral head asphericity and trochanteric overgrowth.
Figure 3: Complex proximal femoral deformities (A and B) typically have a highriding trochanter, a short neck with varus configuration, and an asphericity in the AP direction, resulting in decreased offset. Relative femoral neck lengthening (C) comprised the following steps: a flat trochanteric osteotomy, reduction of the stable part of the greater trochanter, (D) osteochondroplasty of the femoral head-neck area to improve offset, and advancement of the trochanteric fragment. Reprinted with permission from Wichtig Publishing: Tannast M, Macintyre N, Stepacher S, Hosalkar HS, Ganz R, Siebenrock KA. A systematic approach to analyse the sequelae of LCDP. Hip Int. 2013; 23: 61-70.
Figure 4: Our proposed algorithm for the surgical correction of post-LCPD deformity on both the femoral and acetabular structures. The correction always begins with the femoral deformity first.
Figure 5: Preoperative (left) and postoperative (right) radiographs. The AP pelvis views show distalization of the greater trochanter through the relative neck lengthening procedure, bringing the trochanteric tip back to the center of the femoral head. The Dunn lateral views show resolution of the anterosuperior cam deformity and improved head-neck offset.
Surgical Correction of Healed Legg-Calve-Perthes Deformity Malcolm Dombrowski MD Orthopaedic Surgery Resident , Michael McClincy MD Associate Professor PII: DOI: Reference:
S1048-6666(20)30009-4 https://doi.org/10.1016/j.oto.2020.100784 YOTOR 100784
To appear in:
Operative Techniques in Orthopaedics
Please cite this article as: Malcolm Dombrowski MD Orthopaedic Surgery Resident , Michael McClincy MD Associate Professor , Surgical Correction of Healed Legg-Calve-Perthes Deformity, Operative Techniques in Orthopaedics (2020), doi: https://doi.org/10.1016/j.oto.2020.100784
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Inc.
Surgical Correction of Healed Legg-Calve-Perthes Deformity
Malcolm Dombrowski, MD, Orthopaedic Surgery Resident1 Michael McClincy, MD, Associate Professor1 1Department
of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA
Manuscript prepared for Operative Techniques in Orthopaedics Corresponding Author: Michael McClincy, MD UPMC Children’s Hospital of Pittsburgh 4401 Penn Avenue Pittsburgh, PA 15224 (412) 692-3257 [email protected] Abstract Healed Legg-Calve-Perthes disease (LCPD) is a complex problem to manage for the treating orthopaedic surgeon. LCPD begins as a pediatric disorder characterized osteonecrosis of the femoral head. Once the initial osteonecrotic insult resolves, the patient is left with a complex deformity of the proximal femur and acetabulum leading to symptomatic femoroacetabular impingement (FAI) and, potentially, hip instability. Throughout this review we will highlight the relevant patient evaluation, radiographic parameters, and surgical algorithm to aid in the management of this difficult problem. Treatment of this condition is best achieved through a surgical dislocation approach to thoroughly address the intra- and extra-articular sources of femoroacetabular impingment, with the occasional patient requiring a redirective acetabular osteotomy to further improve morphology and function.
Introduction Legg-Calve-Perthes disease (LCPD) is a pediatric disorder characterized by osteonecrosis of the femoral head. The osteonecrotic lesion ultimately heals, but residual deformity to the proximal femur and acetabulum can continue to cause hip pain and dysfunction after the healing process. Previous reports have noted anywhere between 30-50% of individuals affected by LCPD to have residual hip symptoms which persist into adulthood.(1–3) The resultant deformities of the hip can lead to the pathologic processes of femoroacetabular impingement (FAI), hip instability, or a combination of both pathologies. The residual effects of LCPD are highly variable, but generally speaking the longitudinal prognosis of the hip can be directly linked to the overall level of femoral head sphericity and joint congruence.(4–6) To understand the morphologic consequences of LCPD, it is imperative to understand the pathologic changes that occur at the start of the disease’s course. Early LCPD is characterized by focal osteonecrosis of the femoral epiphysis. This process entails damage to the epiphyseal bone as well as the proximal physis. Epiphyseal damage may result in femoral head asphericity, coxa magna, or coxa plana after healing, while damage to the proximal physis may result in coxa breva and a high-riding greater trochanter (Figure 1). On the acetabular side, retroversion is commonly encountered in LCPD patients, and acetabular remodeling in response to significant proximal femoral deformity may lead to an adaptive form of acetabular dysplasia.(7) Successful treatment of deformity following LCPD requires an ability to accurately identify and subsequently improve the varied pathomorphology encountered. The goal of treatment is a stable, concentrically reduced joint with an optimized range of motion. Patient Evaluation History Symptoms caused by the morphologic abnormalities encountered in healed LCPD deformities reflect those encountered in the idiopathic cases of FAI and dysplasia.
Classic FAI is characterized by the abnormal, repetitive contact of the anterior femoral head and neck with the anterior acetabulum. In the healed LCPD hip, this impingement can result from morphologic changes on either the proximal femur or acetabulum. This abnormal contact leads to progressive damage to the acetabular cartilage, acetabular labrum, or both.(8) Patients with FAI tend to have anterior groin pain and pain in the “c-sign” region of the hip, which is aggravated by physical activity, prolonged sitting, and positions of flexion and internal rotation. Stiffness or loss of motion is also quite common and can at times become symptomatic prior to the onset of pain. Extra-articular FAI, involving contact between the trochanters and the pelvis, can also be seen. It presents as posterolateral hip pain with extension activities when localized to the greater trochanter and posterior groin pain with extension activities when localized to the lesser trochanter. Instability symptoms typically manifest during upright activities such as walking or running. Pain in these cases typically localizes to the anterior groin. Complaints of muscular fatigue and pain along the psoas and tensor fascia latae may be subtle indications of instability in these patients. Abductor fatigue and a perceived limp can be related to instability but also may be a product of the high-riding greater trochanter and associated inefficiency of the gluteal musculature. Symptoms of locking at “catching” of the hip joint with activity may be indicative of articular pathology such as labral tears, cartilage flaps, or loose bodies. Imaging Initial imaging of patients with healed LCPD deformity should provide a thorough analysis of both the proximal femoral and acetabular morphology. Routine radiographs should include a standing AP pelvis, lateral view of the proximal femur (45° Dunn recommended), and a false profile view of the acetabulum. Measurements of proximal femoral deformity (alpha angles, head-neck offset ratios) should be performed on both AP and lateral views, and coxa magna and plana should be scrutinized on the AP pelvis. The position of the greater trochanter with
respect to the femoral head, as well as the femoral neck-shaft axis should be measured on the AP pelvis film. On the acetabular side, measurements of acetabular coverage (lateral center edge angle, Tonnis roof angle, anterior center edge angle, anterior/posterior wall indices) should be measured. Markers of acetabular retroversion, such as the crossover sign, posterior wall sign, and prominent ischial spine sign, should be observed. Careful attention should be paid to the markers of acetabular retroversion as LCPD patients occasionally present with a flexion contracture of the hip, which may rotate the pelvis and limit applicability of the retroversion markers. Due to the often-significant deformity present in these patients, we also recommend routine cross-sectional imaging in this patient group. CT and MRI are both reasonable imaging modalities for this purpose. Both provide improved means to measure the acetabular and femoral version in these patients, both of which are important to identify in these patients. CT has the added benefit of generating 3dimensional reconstructions that can be invaluable in the appreciation of complex deformities, but it comes at the cost of added radiation to the patient. MRI has the benefit of providing soft tissue details and thorough evaluation of the femoral headneck junction through radial imaging, however it lacks the bony detail provided by CT and cannot be easily converted to a 3-dimensional image. Clinical Case A 21 year old male presented for evaluation of a continually painful right hip. His history was remarkable for a varus proximal femoral osteotomy at the age of 6 for Pillar B/C hip which failed conservative treatment. He subsequently underwent a valgus proximal femoral osteotomy at the age of 15 for pain and impingement. At the time of our evaluation, he still had significant impingement related symptoms which made seated activities difficult. He was noted to have hip flexion to 80 degrees with >5 degrees of obligate external rotation in this position. He had intraarticular impingement signs on exam as well as posterior impingement features
with external rotation applied in either hip flexion or extension. His pre-operative radiographs and CT scan are shown in Figure 2 A-C. Pathomorphology of Healed LCPD Following resolution of the acute phase of LCPD, patients can present with a variety of morphological pathology on both the proximal femoral and acetabular sides of the hip joint. Femoral Pathomorphologic Subtypes -Intraarticular impingement: Cam-type deformity Classically, cam-type deformity of the proximal femur develops due to an overgrowth of the inferior and antero-lateral aspects of the femoral head. This overgrowth pattern is the result of physeal disruption during the active phases of osteonecrotic insult. In these individuals, the “true” femoral head lies in a position superior and posteromedial and articulates with the acetabulum.(9) In these cases, the true femoral head articulates with the acetabulum in upright activities, however in flexion, the aspherical aspect of the femoral head engages within the anterolateral acetabulum. Other sites of potential asphericity in response to LCPD include medial or posteroinferior osseous spurs which impinge on the acetabular fossa or posteroinferior acetabulum, respectively. The cam-type impingement leads to shear forces on the acetabular cartilage and the chondrolabral junction and predisposes to chondrolabral junction tears and cartilage delamination.(8) Relative femoral head retroversion is a variant of cam-type deformity and arises in certain cases of LCPD where there is a significant discrepancy in the positioning between the anterolateral “false” femoral head and the posteromedial “true” femoral head. This discrepant position places the articulating posteromedial head out of line with the femoral neck into a position of relative retroversion.(9–11) Patients with this deformity have notable trouble with hip flexion without significant compensatory external rotation.(12)
Treatment: With cam-type deformities of the proximal femur, our suggested treatment method is a femoral head/neck osteoplasty through a surgical dislocation approach, which affords circumferential access to the femoral head/neck and acetabulum. When considering the degree of osseous resection in cases of healed LCPD deformity, the use of Mose spheres intraoperatively, along with frequent dynamic examinations, are used to determine the optimal degree of resection. In cases of relative femoral retroversion, where femoral osteoplasty does not completely resolve the motion restrictions, an intertrochanteric flexion/internal rotation osteotomy can be performed to improve the alignment of the articulating femoral head with the remainder of the femur.(13) -Intraarticular impingement: Pincer-type deformity Pincer-type impingement of the proximal femur is a relatively rare condition, with the predominance of pincer lesions arising from the acetabulum. In LCPD these deformities arise in the same manner as cam-type deformities and are characterized by marked asphericity of the native femoral head. Unlike cam-type deformities, the pincer-type deformities are misshapen to a degree that prevents the involved portions of the femoral head from entering the acetabulum. Pincer deformities typically result in significant labral injury and detatchment due to the mechanical compression of this struction between the acetabular rim and proximal femur.(8) Significant degrees of motion restriction can also lead to impingement cysts on the femoral neck and contre-coup injuries to the posterior acetabulum due to impingement-driven instability.(14–16) (12-14) Coxa magna and coxa plana are radiographic markers suggestive of this dramatic deformity.(17,18) Von Rosen (abduction – internal rotation) views can help identify this morphology preoperatively, but intraoperative inspection of motion restriction is the most reliable means of diagnosis. In a select group of patients with a combination of coxa magna and plana deformities, a central area of necrotic subchondral bone persists in the femoral head, and the combined deformities results in a hinge type joint with frontal plane motion but limited abduction (ie. hinged abduction).
Treatment: With pincer-type proximal femoral deformity, our treatment protocol starts with a surgical hip dislocation. Upon accessing the femoroacetabular articulation, a careful inspection of motion restriction and regions of impingement is imperative. In cases where the femoral head cartilage and associated subchondral bone appear intact, an osteoplasty should be performed, again using Mose spheres and dynamic examinations as the guides for performing the bony resection. A flexion intertrochanteric osteotomy can be added to reorient the femoral head within the acetabulum in cases with residual impingement following thorough osteoplasty. -Extra-articular impingement: Greater trochanter Epiphyseal disruption during LCPD frequently effects the longitudinal growth from the proximal femoral physis while the greater trochanteric apophysis and femoral neck appositional growth continue on normal trajectories.(19) The resultant deformity is a short and wide femoral neck, termed coxa brevis, and a high riding greater trochanter. It is important to note that healed LCPD deformity does not typically present with a varus deformity unless a prior containment osteotomy was performed. The clinical manifestations of this deformity are extra-articular impingement, specifically with hip abduction in a neutral or extended position with external rotation, causing the greater trochanter to hit the ilium.(20) Abductor weakness and associated limp is also common due to the position of the greater trochanter. Treatment: Goals of treatment are to resolve the extra-articular impingement by the greater trochanter and improve the lever arm function for the gluteal musculature. Again through a surgical dislocation approach as described previously, a relative femoral neck lengthening procedure can be performed by resection of the stable trochanteric base after digastric osteotomy, followed by distalization of the mobile trochanteric segment after completion of intra-articular work (Figure 3).(21) The
trochanteric fragment is ideally translated until its tip lies at the level of the center of the femoral head, where it is fixated with two or three 4.5mm screws. Acetabular Pathomorphologic Subtypes Acetabular dysplasia and retroversion in LCPD are reactive conditions related to the repetitive collision of the proximal femur and acetabulum that results in premature closure of the triradiate cartilage.(20,22) Acetabular abnormalities are seen more commonly in cases involving significant proximal femoral patho-morphology.(7,22) The degree of acetabular dysplasia or retroversion and hip instability must be appreciated prior to surgery but also must be reassessed after correction of femoral-sided deformity. Treatment: The majority of patients presenting for surgical correction of LCPD deformity will have reached skeletal maturity. As such, our recommended acetabular reorientation procedure in patients with instability findings after proximal femoral reconstruction is the Bernese periacetabular osteotomy (PAO). One technical consideration during PAO in the treatment of acetabular dysplasia in LCPD is that over-coverage and iatrogenic impingement should be avoided. A “conservative” acetabular orientation correction is recommended in this patient group. As the proximal femur remains imperfect in LCPD, less acetabular constraint can be advantageous and iatrogenic impingement catastrophic. Mixed Pathomorphology Types The vast majority of patients with healed LCPD deformities will present with hips with a wide variety of both proximal femoral and acetabular pathomorphologies. Our proposed flowchart for management of healed LCPD deformity is shown in Figure 4. The proximal femoral changes ubiquitously make patients susceptible to femoroacetabular impingement and the resultant joint damage and dysfunction. The proximal femoral deformity should be addressed first in all patients with healed
LCPD. Our typical approach involves a surgical hip dislocation with extensive femoral osteochondroplasty for intra-articular impingement followed by a relative femoral neck lengthening in cases with extra-articular impingement. In cases with significant deformity of the proximal femur that cannot be addressed by osteochondroplasty alone, we perform a redirecting intertrochanteric osteotomy to better orient the articular femoral head within the acetabulum. After complete correction of proximal femoral morphology, we turn our attention to the acetabular side. In cases with residual impingement due to an acetabular pincer deformity, we perform a focal acetabuloplasty or acetabular reorientation osteotomy based on the global acetabular morphology. In cases with resultant instability, we perform a PAO to reorient the acetabulum into a position to optimize stability while avoiding impingement. Clinical Case Our patient underwent a surgical dislocation of the right hip with an extensive osteoplasty of the proximal femur with a large region of bone resection from the anterior and superior aspect of the femoral head down to the base of the anterior greater trochanter. A relative neck lengthening was also performed to facilitate distalization of the greater trochanter and improve tensioning of this abductor musculature. His post-operative radiographs are seen in Figure 5. He had a substantial improvement in function and range of motion after surgery. At 1 year from surgery, the patient was regularly exercising including weight training and cycling with little pain complaints or functional limitations. Outcomes The modern approach to healed LCPD deformity, as described above, has been described in small case series with mid-term follow-up (3-4 years).(23–27) The majority of patients underwent femoral osteoplasty and relative neck lengthening procedures (>60%), while only a fraction required proximal femoral osteotomies (~25%) or periacetabular osteotomies (~10%). The majority (75%) of patients
showed improvement in hip function and pain at final follow-up, with 40% reporting no hip pain. Nearly 10% of patients failed their reconstructive procedure and went on to total hip arthroplasty. Conclusion Residual deformity following healed Legg-Calve-Perthes disease is a cause of hip pain and dysfunction in young, active people. Treatment of this condition is best achieved through a surgical dislocation approach to thoroughly address the intraand extra-articular sources of femoroacetabular impingment. In certain cases, periacetabular osteotomy may also be indicated in cases of hip instability after correction of proximal femoral deformity.
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Figure Captions:
Figure 1: AP radiograph of a post-LCPD hip deformity with a markedly aspherical femoral head and high-riding greater trochanter.
Figure 2: Preoperative radiographs: (A) AP Pelvis showing an aspherical femoral head (sagging rope sign) and a high riding greater trochanter. The acetabulum has developed some undercoverage, likely from the femoral deformity; (B) 45 degree Dunn lateral showing marked anterosuperior asphericity of the femoral head-neck junction with loss of offset; (C) 3-D CT reconstructions showing the femoral head asphericity and trochanteric overgrowth.
Figure 3: Complex proximal femoral deformities (A and B) typically have a highriding trochanter, a short neck with varus configuration, and an asphericity in the AP direction, resulting in decreased offset. Relative femoral neck lengthening (C) comprised the following steps: a flat trochanteric osteotomy, reduction of the stable part of the greater trochanter, (D) osteochondroplasty of the femoral head-neck area to improve offset, and advancement of the trochanteric fragment. Reprinted with permission from Wichtig Publishing: Tannast M, Macintyre N, Stepacher S, Hosalkar HS, Ganz R, Siebenrock KA. A systematic approach to analyse the sequelae of LCDP. Hip Int. 2013; 23: 61-70.
Figure 4: Our proposed algorithm for the surgical correction of post-LCPD deformity on both the femoral and acetabular structures. The correction always begins with the femoral deformity first.
Figure 5: Preoperative (left) and postoperative (right) radiographs. The AP pelvis views show distalization of the greater trochanter through the relative neck lengthening procedure, bringing the trochanteric tip back to the center of the femoral head. The Dunn lateral views show resolution of the anterosuperior cam deformity and improved head-neck offset.