Surgical hip dislocation technique through the femoral head fovea fenestration and impaction bone grafting for the treatment of non-traumatic osteonecrosis of the femoral head: a retrospective study

Abstract

Background

Osteonecrosis of the femoral head (ONFH) often leads to the collapse of the femoral head, ultimately resulting in patients undergoing premature total hip arthroplasty (THA). The surgical hip dislocation (SHD) technique is a type of hip-preserving surgery aimed at delaying or avoiding THA. This study aims to evaluate the clinical efficacy of SHD techniques through femoral head fovea fenestration and impaction bone grafting for the treatment of non-traumatic ONFH.

Methods

A retrospective analysis was conducted on the clinical data of 39 patients (39 hips) with non-traumatic ONFH who underwent SHD for treatment from 2016 to 2017. The Harris hip score (HHS) and the minimum clinically important difference (MCID) are used to evaluate clinical outcomes, while radiographic evaluations are conducted using X-rays. Kaplan-Meier survival analysis defined clinical failure as further THA, and conducted univariate survival analysis and Cox regression analysis. Any complications were recorded.

Results

All patients were followed up for 24–72 months, with an average of (60 ± 13.0) months. At the last follow-up, based on the HHS, 25 patients (64.1%) reported excellent and good clinical outcomes. 29 patients (74.3%) achieved MCID. Imaging evaluation of the postoperative femoral head status showed that 6 cases improved, 20 cases remained stable, and 13 cases showed progressed. Out of 39 hips, 12 hips had postoperative clinical failure, resulting in a clinical success rate of 69.2%. Association Research Circulation Osseous (ARCO) stage, China-Japan Friendship Hospital (CJFH) classification, and postoperative crutch-bearing time are risk factors for clinical failure. Postoperative crutch-bearing time of less than 3 months is an independent risk factor for clinical failure. After surgery, there was one case of sciatic nerve injury and one case of heterotopic ossification. There were no infections or non-union of the greater trochanter osteotomy.

Conclusion

The SHD technique through the femoral head fovea fenestration and impaction bone grafting provides a safe and effective method for treating non-traumatic ONFH, with good mid-term clinical outcomes. ARCO staging, CJFH classification, and postoperative crutch-bearing time are risk factors that affect clinical outcomes after surgery and lead to further THA. Insufficient postoperative crutch-bearing time is an independent risk factor for clinical failure.

Introduction

Osteonecrosis of the femoral head (ONFH) is a common and challenging condition in orthopedics, representing one of the primary causes of hip pain and functional impairment [1]. ONFH refers to the injury or disruption of the blood supply to the femoral head caused by various factors, leading to the death of bone marrow components and osteocytes. This results in the breakage, absorption, and subsequent repair of bone trabeculae, primarily affecting young individuals. It is often accompanied by progressive collapse of the femoral head and joint destruction, subsequently leading to hip osteoarthritis [2]. The natural progression of ONFH is rapid, and without timely and effective intervention, most patients can only undergo total hip arthroplasty (THA), thereby placing a heavy burden on society and families [3, 4]. Due to complications such as aseptic loosening and infection of the prosthesis, as well as limitations in the longevity of the prosthesis, younger patients may need to undergo multiple total hip revision surgeries [5]. Therefore, choosing a treatment option that can preserve the femoral head, delay the progression of ONFH, and postpone or prevent THA is the goal of orthopedic surgeons’ exploration. Although there are various hip preservation surgical procedures, due to differences in the etiology, staging, and classification of ONFH, the treatment outcomes vary significantly. Therefore, there is still controversy regarding the selection of the appropriate treatment modality [6,7,8,9]. The surgical hip dislocation (SHD) Technique has been increasingly promoted in the field of hip preservation and was first introduced by GANZ et al. This technique allows for full exposure of the femoral head, observe the state of ONFH, completely remove necrotic bone, and restore the shape and structure of the femoral head [10]. However, there are few reports on the treatment of non-traumatic ONFH using SHD via femoral head fovea fenestration and impaction bone grafting. Therefore, the purpose of this study was to report the therapeutic efficacy of using SHD technique via femoral head fovea fenestration and impacting bone grafting for the treatment of non-traumatic ONFH. The primary outcome was to evaluate the quality of hip joint functional recovery, survival rate, and clinical and radiographic results. The secondary outcome was to analyze the risk factors that might affect clinical efficacy.

Methods

Study design

From January 2016 to December 2017, we treated 39 patients (39 hips) with non-traumatic ONFH using SHD. There were 28 males and 11 females, aged between 25 and 48 years, with an average age of (35.1 ± 4.5) years. The etiological were categorized into idiopathic, alcoholic, and hormonal. The underlying diseases in the hormone group were ocular inflammation, nephrotic syndrome, nephritis, fever, measles, eczema, systemic lupus erythematosus, and lumbar disc herniation. All patients had a long-term or high-dose history of hormone use. Preoperative pelvic anteroposterior and frog position radiographs, as well as hip CT and MRI were performed. The ONFH staging adopts the Association Research Circulation Osseous (ARCO) stage and the China-Japan Friendship Hospital (CJFH) classification. The patient demographics are presented in Table 1. Due to the retrospective nature of this study, the local ethics committee of our institution declined to provide ethical approval for the research. Informed consent was obtained from all patients prior to the procedure.

Table 1 Demographic characteristics of patients

Surgical methods

After the patient’s anesthesia has taken effect, they are placed in a lateral position on their healthy side, and routine disinfection and draping are performed. The Kocher-Langenbeck incision is chosen, taking the greater trochanter as the center to incise the lateral side of the hip joint, sequentially incising through the skin, subcutaneous tissue, and deep fascia. At the 1/3 point anterior to the greater trochanter, incise the fascia and tensor fascia latae muscle to expose the middle and lesser glutes. Then, perform an osteotomy at the greater trochanter, with a thickness of approximately 1.5 cm. Use a retractor to retract and protect the osteotomy fragment, expose the joint capsule, perform a “Z” incision on the joint capsule, retract and flex the hip joint, and then sever the round ligament to complete the femoral head dislocation. A bone window of approximately 1.0 cm × 1.5 cm was opened at the concave of the femoral head with osteotome. Osteotome and curette can be used to remove the necrotic bone tissue under direct vision until satisfactory punctuate bleeding on the bone surface. Iliac bone was harvested from the iliac crest near the incision, and cancellous bone was harvested from the greater trochanter osteotomy site. Autologous bone and bioceramic bone (3.5–5.0 mm, model: β-tricalcium phosphate 3 g cancellous bone particles, Shanghai Bio-Alloy Biomaterials Co., Ltd.) were used to fill the impaction graft to close the fenestration. The hip joint was reset, a negative pressure drainage tube was placed, the joint capsule was sutured in a “Z” shape, the greater trochanter osteotomy block was reset and fixed with screws, and the tissues were sutured layer by layer. A typical case is shown in Fig. 1.

Fig. 1

Male, 31 years old, etiology: alcoholic. MRI (A and B) showed osteonecrosis of the femoral head. CT (C and D) showed cystic bone defects in the necrotic area, involving the articular surface. Preoperative pelvic anteroposterior and frog position radiographs (E and F) showed decreased bone mineral density in the necrotic area within the femoral head. A bone window (G) was opened at the concave of the femoral head to clean up the necrotic bone tissue under direct vision. The pelvic anteroposterior and frog position radiographs (H and I) at postoperative day 5 showed an increase in bone mineral density in the bone graft area. At the last follow-up, the pelvic anteroposterior and frog position radiographs (J and K) showed increased density of the bone graft area, stable morphology of the femoral head, good healing of the greater trochanter osteotomy, and strong internal fixation

Postoperative management

Antibiotics were routinely used to prevent infection, anticoagulant therapy with low molecular weight heparin calcium, and drainage was removed after 24 to 48 h. Functional exercise was mainly based on isometric muscle contraction, and hip rotation, abduction and adduction exercises were performed During the first 3 months, weight-bearing activities of the operated limb were avoided. Within the second 3 months, the operated limb gradually transitioned from partial weight-bearing to full weight-bearing under the protection of double crutches. Full weight-bearing activity followed, but strenuous activity was avoided for 1 year.

Clinical and imaging evaluation

Follow-up was planned at 3 months, 6 months, 12 months and annually after surgery. The operation time, intraoperative blood loss and complications were recorded. Due to the inconsistent medical compliance of patients, the postoperative crutch-bearing time was recorded. During the follow-up, pelvic anteroposterior and frog position radiographs were taken, and hip CT or MRI was performed when necessary. The Harris hip score (HHS) and minimal clinically important difference (MCID) were used to evaluate the functional recovery of the hip joint. HHS less than 70 was considered as poor, 70 to 79 as fair, 80 to 89 as good, and more than 90 as excellent. MCID was defined as an increase of at least 10 points in HHS at the last follow-up compared with that before surgery. Imaging evaluation was completed by the same senior physician. Imaging evaluation: the morphology of the femoral head was stable, and partial or complete repair of the necrotic area was considered to be improvement. The morphology of the femoral head was stable, and no change in the necrotic area was considered stable. Progressive collapse of the femoral head, expansion of the necrotic area, joint space narrowing, or arthritis were considered progression (radiographic failure). Clinical failure was defined as further THA after SHD. The time for conversion THA was regarded as the last follow-up, and the HHS at this time was regarded as the final score.

Statistical analysis

Statistical analysis was performed by two investigators using SPSS (version 20.0, IBM Corp., Armonk, NY, USA). The count data were expressed as n, and the measurement data were expressed as mean ± standard deviation. t-test was used. Univariate analysis of risk factors was performed using Kaplan-Meier survival curves, and log-rank test was used. p < 0.05 was considered as statistically significant. The analysis factors included gender, age, body mass index (BMI), side, etiology, postoperative crutch-bearing time, ARCO stage, and CJFH classification; Cox multivariate risk model was used for regression analysis of risk factors.

Results

All patients were followed up for 24 to 72 months, with an average of 60 ± 13.0 months. The HHS score of 39 patients increased from 61.99 ± 4.42 preoperatively to 81.18 ± 9.73 postoperatively (p < 0.05). According to the HHS, 25 hips (64.1%) achieved excellent and good results, and 29 hips (74.3%) achieved MCID. According to the imaging evaluation, the hip improved in 6 cases (15.4%), stabilized in 20 cases (51.3%), and progressed in 13 cases (33.3%). 1 case showed progression, but the patient’s daily life was not seriously affected and was still under observation and follow-up. A total of 12 hips underwent further THA in the postoperative follow-up phase, which was defined as clinical failure. The course of conversion from SHD to THA ranged from 24 to 52 months, with an average of 42.5 ± 7.34 months. Univariate analysis of Kaplan-Meier survival curve revealed that ARCO stage, CJFH classification and postoperative crutch-bearing time were risk factors for clinical failure (Table 2). Significant factors of survival curve are shown in Fig. 2. Cox regression analysis showed that postoperative crutch-bearing time of less than 3 months was an independent risk factor for clinical failure (Table 3). Postoperative sciatic nerve injury occurred in 1 case, and Brooker grade I heterotopic ossification occurred in 1 case. No other serious complications occurred.

Table 2 The risk factors were analyzed by univariate analysis

Fig. 2

The survival curve of postoperative crutch-bearing time (A), ARCO stage (B) and CJFH classification (C)

Table 3 COX regression analysis of risk factors

Discussion

At present, the pathogenesis of ONFH is still unclear, and it is considered to be related to alcohol, hormones, trauma and other factors in clinical practice [11]. Due to the insidiousness of its onset, most patients in our region go to the outpatient clinic for treatment due to severe hip pain, so the early stage of the disease is often missed, resulting in difficult situations such as a large area of necrosis, subchondral fracture, articular surface collapse and so on. THA is the ultimate treatment for ONFH, but young and middle-aged patients will face the risk of multiple revisions in the future. Therefore, it is necessary to perform effective hip-preserving surgery to retain the femoral head to delay or avoid THA.

SHD has been widely used in impingement syndrome, femoral head fracture, Legg-Calve-Perthes disease, etc., but there are relatively few reports on the application of hip preservation for ONFH [12,13,14]. Dewar et al. [15] showed through quantitative MRI analysis that the main arterial supply of the femoral head came from the medial femoral circumflex artery (MFCA) (82%), and the rest came the lateral femoral circumflex artery (LFCA). Gautier et al. [16] found that the MFCA reached the posterior joint capsule between the external obturator muscle and the adductor brev muscle, and continued along the intertrochanteric ridge to the posterior superior part of the femoral neck, and its terminal vascular branches supplied the blood supply to the outer superior part and inner inferior part of the femoral head. Kalhor et al. [17] found that the deep branch of the MFCA enters the femoral head between the quadratus femoris and the external obturator muscle. Therefore, the surgical hip dislocation technique can completely preserve the external rotator group of the hip joint, thereby protecting the MFCA and providing a blood supply basis for the treatment of ONFH. GanZ et al. [10] showed no osteonecrosis of the femoral head in the clinical results of 213 hips treated with SHD, which confirmed the safety of this technique in the hip-preserving treatment of ONFH. With this technique, the femoral head can be completely exposed without damaging the blood supply to the femoral head, so that the necrotic bone can be removed under direct vision. At the same time, the cancellous bone and autogenous iliac bone from the greater trochanter can be transplanted to reconstruct the weight-bearing area of the femoral head and restore the flat articular surface. Shen et al. [18] treated 53 hips with SHD, followed up for an average of 20 months, and the postoperative HHS was 83.2 ± 5.8, and 2 hips (3.8%) were converted to THA. Yao et al. [19] used SHD to treat 8 patients with ONFH at ARCO stage IIIA-IIIB, with an average follow-up of 18.6 months. The postoperative HHS was 80.53 ± 7.62, and only 1 hip (12.5%) received THA. Steppacher et al. [20] applied SHD to 13 hips, followed up for an average of 36 months, and 1 patient underwent THA due to necrosis progression. Sun et al. [21] used SHD to follow up 28 hips for an average of 25.8 months, and the HHS was 88.74 ± 1.68. A total of 5 hips (17.9%) progressed and received THA. The results of this study showed that 39 hips were treated with SHD, with an average follow-up of 60 months. The HHS was 81.18 ± 9.73, and the excellent and good rate was 64.1%. 13 cases had radiographic progress, of which 12 cases (30.7%) received THA due to clinical failure. The mean HHS was similar to that reported previously, indicating that treatment of ONFH with SHD was effective in relieving pain and improving hip function. The number of clinical failure cases after SHD was greater, which may be related to the longer follow-up time. However, the overall clinical success rate was 69.2%, which could delay the process of osteonecrosis and achieve the purpose of postponing or avoiding premature THA.

Some previous studies have used SHD to treat ONFH while adding platelet‑rich plasma, traditional Chinese medicine, autologous matrix induction and other technologies, aiming to promote the repair of femoral head necrosis and improve the survival rate of the hip after surgery [20, 22, 23]. In this study, the cancellous bone from the greater trochanter was used for bone transplantation under the same surgical approach, and the autologous iliac bone was removed from the proximal end of the incision to reconstruct the bone support of the anterolateral region of the femoral head without changing the surgical position. In addition, the degradation rate of β-tricalcium phosphate biocrystals is similar to that of new bone formation, which not only has the advantages of biocompatibility and tissue conduction but also has a composition of degradation products close to the inorganic composition of human bone, which is conducive to the mineralization of the bone matrix and its osteoinductive properties [24, 25]. Therefore, on the basis of autologous bone grafting combined with β-tricalcium phosphate bioceramics is beneficial for bone formation, bone defect repair, and reconstruction.

The size and location of the necrosis often predict the further collapse of the femoral head, which is an important factor affecting the prognosis of hip preservation treatment. The weight-bearing area of the femoral head is the top and anterolateral area, and the anterolateral area is more important. The stability of this area is the key to successful of hip preservation. Relevant mechanical tests have proved that the peak pressure on the anterolateral side of the femoral head can reach 7 times of the autologous mass [26, 27]. When the necrosis is located within the edge of the acetabulum, the anterolateral area has complete bony support, and it does not easily collapse after surgical repair. When the necrosis is located in the anterolateral region, especially when the lateral column has only part of normal one, the support strength is general, and the retention rate of the femoral head after repair is high. When all the bones of the lateral column are destroyed, there is no support strength in the weight-bearing area, and the prognosis is the worst [1]. A systematic review reported that patient age, BMI, etiology, and the side did not show evidence of a statistically significant association with surgical outcome [28]. The same conclusion was obtained by univariate analysis of Kaplan-Meier survival curves in this study. However, ARCO stage, CJFH classification, and postoperative crutch-bearing time were risk factors for hip preservation failure. Notably, postoperative crutch-bearing time of less than 3 months is an independent risk factor for hip preservation failure. Although the importance of avoiding premature weight-bearing of the operated limb during early activities was repeatedly emphasized in postoperative education, and the time nodes of weight-bearing and exercise were strictly planned, it was found that some patients had carried out full weight-bearing activities of the lower limbs in the early postoperative period. Especially for patients whose bone of the anterolateral column is completely destroyed by the necrotic focus, this area is too affected early to be subjected to pressure caused by body weight after SHD repair, which is easily loosens the stable bony support of the bone graft, leading to hip preservation failure.

The main disadvantages of SHD are as follows: when the operation is not performed properly, it may cause iatrogenic injury to the blood supply of the femoral head, leading to the progression of femoral head necrosis. Delayed union or nonunion may occur at the site of greater trochanter osteotomy. The surgical incision is large, and the soft tissue is greatly damaged. The incision has defects in aesthetics. Although SHD is more traumatic than hip-preserving procedures such as core decompression and complications such as heterotopic ossification, and infection may occur, the occurrence probability of relevant reports is low. Sink et al. [29] studied the complications of SHD and showed that the incidence of complications was 10% in 334 hips. In this study, there was 1 case of sciatic nerve injury and 1 case of Brooker’s grade I heterotopic ossification, both of which recovered completely after a period of rehabilitation.

There are several limitations in this study. First, retrospective analyses have inherent limitations in terms of study design. Second, the single-center study resulted in a small sample size, which may affect the regression analysis of the relevant factors. Finally, there was no control group for the other surgical procedures. In the future, we will increase the sample size in multiple centers, continue to observe the long-term clinical efficacy and conduct further research.

In conclusion, SHD through the femoral head fovea fenestration and impacting bone grafting for the treatment of non-traumatic ONFH can more directly correct the collapse of the femoral head, remove the necrotic bone, reconstruct the biomechanical stability of the femoral head, restore hip function, relieve pain, and protect the deep branch of the MFCA. It is a safe and effective surgical method with good clinical efficacy. It can achieve the goal of delaying or avoiding premature THA. The ARCO stage, CJFH classification and the postoperative crutch-bearing time may affect the success rate of hip preservation, especially the planning of limb weight-bearing activities after SHD.