Correction of post-LCP (Legg–Calve–Perthes) morphology using surgical hip dislocation with retinacular flap and relative femoral neck lengthening for impingent correction reduces the risk of early arthritis and improves the survival of the native hip joint.
Indications
Typical post-LCP deformity with external and internal hip impingement due to aspherical enlarged femoral head and shortened femoral neck with high riding trochanter major without advanced osteoarthritis (Tönnis classification ≤ 1) in the younger patient (age < 50 years).
Contraindications
Advanced global osteoarthritis (Tönnis classification ≥ 2).
Surgical technique
By performing surgical hip dislocation, full access to the hip joint is gained which allows intra-articular corrections like cartilage and labral repair. Relative femoral neck lengthening involves osteotomy and distalization of the greater trochanter with reduction of the base of the femoral neck, while maintaining vascular perfusion of the femoral head by creation of a retinacular soft-tissue flap.
Postoperative management
Immediate postoperative mobilization on a passive motion device to prevent capsular adhesions. Patients mobilized with partial weight bearing of 15 kg with the use of crutches for at least 8 weeks.
Results
In all, 81 hips with symptomatic deformity of the femoral head after healed LCP disease were treated with surgical hip dislocation and offset correction between 1997 and 2020. The mean age at operation was 23 years; mean follow-up was 9 years; 11 hips were converted to total hip arthroplasty and 1 patient died 1 year after the operation. The other 67 hips showed no or minor progression of arthrosis. Complications were 2 subluxations due to instability and 1 pseudarthrosis of the lesser trochanter; no hip developed avascular necrosis.
Hinweise
Redaktion
T. Slongo, Bern
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Introductory remarks
Legg–Calve–Perthes (LCP) disease is an aseptic osteonecrosis of the femoral head of the developing hip. The course of the disease can be divided into typical stages according to Waldenström (Infobox; [9, 20]). The disease shows an inhomogeneous appearance. Some patients show only mild deformations and have little or no late effects, some are affected more severely with early development of arthritis, and some patients are limited in their daily life even before developing osteoarthritis due to impaired range of motion of the hip joint. Around 20% of patients are affected bilaterally [12]. The altered shape of the proximal femur after LCP disease can cause restricted range of hip motion, femoroacetabular impingement, hip pain, and joint degeneration in young adults [3, 5]. The typical post-LCP deformity in the mature hip consists of a mushroom-shaped head, femoral neck shortening and relatively high riding trochanter. Additional acetabular deformities such as hip dysplasia or retroversion are frequent. Functional problems can result due to femoral or acetabular pathomorphology.
Femoral functional problems can result from the intraarticular cam impingement due to the aspherical enlarged femoral head. If the head is too large to slip under the acetabular rim a head-induced pincer impingement with hinged abduction will occur. In addition, functional retrotorsion of the femur with intraarticular impingement can also occur.
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Other femoral functional problems are the extraarticular impingement of the greater trochanter with limited external rotation in flexion and abduction or the extraarticular impingement of the lesser trochanter on the ischial tubercle with limited external rotation in extension. Typical acetabular pathologies consist of dysplasia, acetabular retroversion, and incongruity [17]. The choice of which surgical treatments to use depends on the pathomorphology of the individual patient and requires a stepwise treatment pathway [7].
In this article, we will focus on surgical hip dislocation with relative femoral neck lengthening for the correction of the intra- and extraarticular impingement and further the development of a retinacular soft-tissue flap for the maintenance of femoral head perfusion [2, 4, 8, 11].
Surgical principle and objective
The aim of surgical hip dislocation with relative femoral neck lengthening is to correct intra- and extraarticular femoroacetabular impingement. Surgical hip dislocation allows an excellent overview of the complete hip joint and allows for intraoperative dynamic testing to evaluate impingement-free range of motion of the hip. In addition, intraarticular corrections like labral and cartilage repair are possible. The relative femoral neck lengthening allows distalization of the greater trochanter and reduction of its base to elongate the femoral neck (Fig. 1). This improves range of motion and corrects intra- and extraarticular impingement of the femoral neck or greater trochanter, respectively. Therefore, a retinacular soft-tissue flap has to be developed to secure femoral head perfusion. For this procedure, precise knowledge of the vascular anatomy of the proximal femur is essential to avoid iatrogenic necrosis [10, 14]. Other deformities such as the head-induced pincer impingement with hinged abduction can be corrected with an additional head reduction osteotomy [2, 16]. The extraarticular impingement of the lesser trochanter can be corrected by distalization.
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Advantages
Surgical hip dislocation [6] provides unrestricted access to the acetabulum and the femoral head including dynamic intraoperative testing of range of motion and impingement.
With development of the retinacular flap, the femoral head perfusion is secured and deformities of the head–neck region close to the retinacular vessels can be corrected [8, 11, 19].
The relative femoral neck lengthening allows distalization of the greater trochanter and reduction of its base to elongate the femoral neck. The goal is to restore range of motion without extra- or intraarticular impingement.
Concomitant procedures such as transposition of the lesser trochanter, head reduction osteotomies, treatment of cartilage and labral lesions or femoral torsion can be performed [18].
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Disadvantages
Technically demanding surgical technique. Without precise knowledge of the vascular anatomy of the proximal femur, there is the risk of iatrogenic necrosis of the femoral head.
Rehabilitation with a minimum 8 weeks of limited weight bearing.
Changes in the abductor lever arm may lead to long rehabilitation with limping.
Trochanteric screws are often irritating requiring hardware removal.
No true leg lengthening
Indications
Post-LCPD(Legg-Calve-Perthes Disease) deformity of the hip with a short femoral neck, aspherical femoral head, and a relative high riding trochanter resulting in extra- and intraarticular hip impingement.
No advanced degenerative signs (Tönnis grade ≤ 1)
Relatively young patient (age < 50 years)
Contraindications
Advanced joint degeneration (Tönnis grade ≥ 2)
Elderly patients (age ≥ 50 years)
Patient information
General surgical risks:
(Thrombosis, pulmonary embolism, allergic reactions, injury of cutaneous nerves with numbness/dysesthesia, excessive bleeding with need of blood transfusion, delayed wound healing and infection)
Specific risks of this procedure:
Delayed union or pseudarthrosis of osteotomy of greater trochanter
Intraarticular adhesions
Heterotopic ossifications
Iatrogenic avascular necrosis due to damage of the retinacular vessels
Preoperative work-up
Detailed clinical and radiological work-up is essential to evaluate whether hip-preserving surgery is indicated. As an alternative, total hip arthroplasty (THA) has to be considered in hips with advanced osteoarthritis.
Detailed patient history (e.g., family history, onset and course of disease, symptoms, previous treatment and operations).
Standardized radiographic imaging including an anteroposterior pelvic radiograph and axial view.
Magnetic resonance (MR) arthrography of the hip, preferably with radial reconstruction and intraarticular contrast injection for evaluation of size and location of cam deformity, congruency of the joint, deformity of greater and lesser trochanter with extraarticular impingement and damage to cartilage or labrum [13].
Axial imaging (computed tomography or magnetic resonance imaging) of hip and knees for evaluation of femoral torsion.
Abduction/internal rotation radiograph for evaluation of congruency or instability of the joint or hinge abduction.
Preoperative templating to define the location of the osteotomy, the type of correction (relative femoral neck lengthening and offset correction or additional femoral head reduction, femoral osteotomy or acetabular osteotomy).
Instruments
Dedicated instruments for hip preservation surgery with special retractors (Subtilis; Accuratus, Bern, Switzerland)
Cortical 3.5 mm screws for refixation of the greater trochanter
Sterile bag on contralateral side to position the leg during surgical hip dislocation
Fibrin glue (Tissuecol; Baxter; Warsaw, Poland) or AMIC (Autologous Matrix-Induced Chondrogenesis) with type I/III collagen matrix (Chondro-Gide; Geistlich Pharma, Wollhusen, Switzerland) for cartilage treatment
Anesthesia and positioning
General anesthesia with full muscle-relaxation
Lateral decubitus position with placement of the leg on a tunnel bolster to avoid pressure on contralateral leg and to have a flat surface in a horizontal position for the involved lower limb
Stabilization of patient with two side supports
Disinfection and sterile drapes including the entire lower extremity up to the thorax. The greater trochanter should be freely palpable.
Fluoroscopy for intraoperative orientation and monitoring of the osteotomy, angular corrections and placement of hardware
Single-shot intravenous antibiotic prophylaxis (cefazolin 2 g i.v.)
Surgical hip dislocation gives an excellent view of the joint to inspect and treat the femoral head, the head–neck junction, acetabulum, damaged cartilage or labrum, and concomitant pathologies to improve joint containment. During surgery, the impingement-free range of motion can be directly evaluated. The retinacular flap allows for correction of the neck while protecting femoral head perfusion. Precise knowledge of the vascular anatomy of the proximal femur is of upmost importance to perform this technically demanding surgery.
Postoperative management
The postoperative protocol includes the use of a continuous passive motion device during the hospital stay, beginning directly postoperatively, to prevent capsular adhesions. After surgery, patients are mobilized with partial weight bearing of 15 kg with the use of crutches for at least 8 weeks. Depending on the performed procedures (head reduction, femoral or acetabular osteotomies) other restrictions may apply. Abduction, adduction as well as flexion more than 90° is restricted to protect the trochanteric osteotomy. Prophylaxis against thrombosis is prescribed until full weight bearing is allowed. Prophylaxis for heterotopic ossification is not applied on a regular basis, as this complication does not occur very often. After radiographic confirmation of healing at the 8‑week follow-up, stepwise return to full weight bearing is allowed and abductor training is initiated. Usually, return to work is possible 3 months postoperative.
Errors, hazards, complications
Iatrogenic lesion to the retinacular vessels with damage to vascular perfusion of the femoral head and avascular necrosis of the femoral head
Intraarticular adhesions (hip arthroscopy might be necessary)
Delayed union or pseudarthrosis of the trochanteric osteotomy can necessitate revision surgery
Hinged abduction due to enlarged and aspherical femoral head (additional head reduction osteotomy might be necessary)
Failure to achieve stability and joint containment (additional periacetabular osteotomy might be necessary)
Heterotopic ossifications
Muscular imbalance, change of gait pattern requiring long rehabilitation
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Results
In a retrospective case series, we evaluated 81 adult patients with history of LCPD, who underwent surgical hip dislocation with relative femoral neck lengthening and retinacular soft-tissue flap (Table 1).
Table 1
Demographics of evaluated patients with surgical hip dislocation
Parameter
Number
Total number of hips (patients)
81 (79)
Tönnis grade preoperative (hips)
Stage 0
41
Stage 1
40
Age at operation (years)
23 ± 7 (6–51)
Gender (% male)
53%
Side (% left)
56%
Preoperative findings
All 81 hips presented with clinical relevant intra- and/or extraarticular impingement following LCPD. Reduced range of motion and pain were the leading symptoms. Of the 81 hips, 41 had preoperative Tönnis stage 0 and 40 hips had Tönnis stage 1. In addition, 46 of the hips had previous operations, mostly intertrochanteric varisation osteotomies.
Procedures
Between October 1997 and October 2020, 81 hips (79 patients) were treated with surgical hip dislocation and offset correction. In 71 hips, a retinacular flap with relative femoral neck lengthening was performed. Concomitant procedures were performed in 32 hips for the labrum, in 11 hips with a periacetabular osteotomy, in 6 hips with a valgus osteotomy, and in 4 hips with a head reduction osteotomy. The mean age at operation was 23 ± 9 (6–51) years.
Follow-up and evaluation
The mean follow-up was 9 ± 7 (range 1–23) years; 11 hips were converted to a total hip arthroplasty (THA) due to progressive arthrosis after a mean 7 ± 4 (range 1–13) years. One patient died 1 year after the operation unrelated to surgery. The remaining 67 hips showed no or minor progression of the arthrosis.
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Revision surgery and complications
None of the patients developed avascular necrosis of the femoral head. Complications included two instabilities with consecutive subluxations, and one patient with pseudarthrosis of the lesser trochanter. Of the 2 patients with instabilities, one received a periacetabular osteotomy and the other patient underwent total hip arthroplasty due to advanced osteoarthritis. The patient with the pseudarthrosis of the lesser trochanter had a revision osteosynthesis and healed trochanter at follow-up. In 43 patients, the trochanteric screws had to be removed. One patient died unrelated to the operation.
Conclusions
Our findings confirm earlier studies that surgical hip dislocation with relative femoral neck lengthening and retinacular soft-tissue flap is an effective treatment option for patients with post-Legg–Calve–Perthes (LCP) deformities [1]. The frequency of pseudarthrosis of the greater or lesser trochanter was similar to the frequency in patients with surgical hip dislocation without relative femoral neck lengthening [2]. The percentage of hips that were converted to THA (14%) is slightly higher than in other studies on results after relative femoral neck lengthening (7% in a follow-up of 3 years [2] and 10% in a follow-up of 3.75 years [15]) but seems to match the results of the other studies regarding the longer follow-up time of 9 years.
Infobox explanation of scores
Waldenström: The classification according to Waldenström groups the disease by typical radiographic signs into five major stages with substages:
1) Initial stage with augmentation of the joint space and joint effusion,
2) Condensation stage with sclerosis of the epiphysis (3–6 months after disease onset),
3) Fragmentation stage with depletion of the bone with cloddy decay (maximum 12 months after onset),
4) Regeneration stage with rebuilding of the bony substance (1–3 years after onset) and
5) End stage with completion of the bony healing with restitutio ad integrum or deformed healing.
Tönnis: Radiographic classification of osteoarthritis.
Grade 0: No arthritis,
Grade 1: Mild thinning of joint space and increased density of supporting bone,
Grade 2: More thinning of joint space, small cysts, more density of supporting bone,
Grade 3: Large cysts, severe narrowing or obliteration of joint space, deformity of femoral head.
Declarations
Conflict of interest
C.S. Leibold, N. Vuillemin, L. Büchler, K.A. Siebenrock and S.D. Steppacher declare that they have no competing interests.
Ethical review board approval was obtained for this study. All patients provided written consent and agreed to attend regular follow-up examinations.
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