A Comparison of Transphyseal Neck-Head Tunneling and Multiple Epiphyseal Drilling on Femoral Head Healing Following Ischemic Osteonecrosis: An Experimental Investigation in Immature Pigs

Perthes disease: comparison of two surgical options

Varus intertrochanteric osteotomy (ITO) remains the most popular method to contain the fragmenting femoral head in Perthes disease. However, resultant compromise of hip abductors may result in coxa brevis and acetabular dysplasia, increasing the risk of requiring future surgery. A minimally invasive strategy of tension plating the greater trochanter was developed in effort to avoid these consequences. The objective is to compare greater trochanter-guided growth to ITO for treatment of Perthes disease. This IRB approved, retrospective review compares two series of children with Perthes, one treated with ITO and one with greater trochanter-guided growth (GG). Clinical examination findings and clinical course were recorded via chart review. Weight-bearing pelvic X-rays were analyzed preoperatively and at the last known follow-up prior to other procedures. There were 58 patients: 18 underwent ITO versus 40 GG. The groups matched in age, sex, examination, and radiographic parameters. Average follow-up was 5 years. The change in the center head-trochanteric distance (CTD) was statistically significant ( P < 0.05), -0.3 cm in GG versus -1.09 cm in ITO patients. At final follow-up, the ITO group was more likely to have LLD ≥ 2 cm (16.67% vs. 0%; P = 0.03) and 52.5% of GG patients were classified as Stulberg III or greater, versus 72.2% of the ITO group ( P < 0.001). Ninety-four percent of ITO patients versus 40% of GG required additional surgery. Containment by ITO reflects exclusive focus upon the femoral head, without considering long-term sequelae. GG addresses the femoral neck issues potentially providing better outcomes. Level of Evidence. This is a level III study providing further understanding of the properties of the proximal femoral physes and an alternative for surgical management of perthes disease.

Local BMP2 hydrogel therapy for robust bone regeneration in a porcine model of Legg-Calvé-Perthes disease

Legg-Calvé-Perthes disease is juvenile idiopathic osteonecrosis of the femoral head (ONFH) that has no effective clinical treatment. Previously, local injection of bone morphogenetic protein-2 (BMP2) for ONFH treatment showed a heterogeneous bone repair and a high incidence of heterotopic ossification (HO) due to the BMP2 leakage. Here, we developed a BMP2-hydrogel treatment via a transphyseal bone wash and subsequential injection of BMP2-loaded hydrogel. In vitro studies showed that a hydrogel of gelatin-heparin-tyramine retained the BMP2 for four weeks. The injection of the hydrogel can efficiently prevent leakage. With the bone wash, the injected hydrogel had a broad distribution in the head. In vivo studies on pigs revealed that the BMP2-hydrogel treatment produced a homogeneous bone regeneration without HO. It preserved the subchondral contour and restored the subchondral endochondral ossification, although it increased growth plate fusions. In summary, the study demonstrated a promising BMP2-hydrogel treatment for ONFH treatment, especially for teenagers.

Does transepiphyseal drilling and closure of the greater trochanter in early Legg-Calve-Perthes disease improve natural history?

PURPOSE

There is no consensus regarding treatment of Legg-Calve-Perthes disease (LCPD). The most common sequel of the disease is coxa breva and overgrowth of the greater trochanter (GT). Our purpose was to examine the effectiveness of transepiphyseal drilling combined with closure of the GT apophysis in patients with LCPD.

METHODS

During 2013-2018, we treated 16 consecutive cases of LCPD. Average age was 7.5 (range 6-10) years; nine patients were in early fragmentation, five in late fragmentation and one in reossification stages. Treatment protocol included hip arthrography, percutaneous drilling of the femoral head epiphysis, percutaneous tenotomy of adductor longus and epiphysiodesis of the GT apophysis.

RESULTS

Mean follow-up was 38 months. One patient was lost to follow-up. All patients had a limp prior to surgery. However, at latest follow-up, 10/15 patients had no limp, 11 patients had substantial improvement in hip range of motion. On radiographs, nine patients had Stulberg type 1-2, one type 3 and five type 4-5. There was no change in the epiphysio-trochanteric distance in any patient. Eight out of nine patients treated in the early fragmentation stage had good clinical and radiographic outcome. Most patients treated in late fragmentation stage had Stulberg 4-5 hip and required additional procedures.

CONCLUSIONS

Based on our preliminary experience, our protocol can be effective in the treatment of patients with LCPD in the initial or early fragmentation stages by improving the clinical and radiographic outcomes of the disease. This minimally invasive approach does not compromise any future treatment options.

LEVEL OF EVIDENCE

IV.

Prognostic value of bone resorption pattern in the anterior portion of the femoral head in Legg-Calvé-Perthes disease

Purpose

To examine whether differences in bone resorption patterns in the anterior portion of the femoral head correlate with the prognosis of Legg-Calvé-Perthes disease.

Methods

Seventy-eight patients with unilateral Legg-Calvé-Perthes disease, who were diagnosed after 6.0 years of age, underwent the Salter innominate osteotomy from 1987 to 2013, and were followed up to skeletal maturity. The anterior bone resorption pattern of the femoral head was evaluated from a frog-leg lateral hip radiograph made in the middle of the fragmentation period, and classified into two types, an epiphysis-preserved type (P) and a physis-disrupted type (D). The correlation between the type of bone resorption and the Stulberg outcome was analyzed.

Results

The Stulberg outcomes were grade I for 9 patients, grade II for 31, grade III for 35, and grade IV for 3, with a mean follow-up period of 8.3 ± 2.7 years. Fifty-one patients demonstrated the type P hips and 27 did the type D hip. In a subset analysis of patients with the modified lateral pillar group-B hips in the younger group (6.0-8.9 years of age at diagnosis), the percentages of the favorable and unfavorable outcomes significantly differed between the two types (p = 0.013). Anteroposterior enlargement of the affected femoral head was significantly greater in the type D hips than the type P hips (p = 0.014).

Conclusion

Unfavorable hip morphology at skeletal maturity can be predicted in patients with the lateral pillar group-B hips by focusing on bone resorption patterns of the anterior portion of the femoral head.

Level of evidence

Level III, prognostic study.

What is New in Pediatric Orthopaedic: Basic Science

BACKGROUND

An understanding of musculoskeletal basic science underpins most advancements in the field of orthopaedic surgery. Knowledge of biomechanics, genetics, and molecular pathways is integral to the understanding of the pathophysiology of disease and guides novel treatment options to improve patient outcomes. The purpose of this review is to provide a comprehensive and current overview of musculoskeletal basic science relevant to pediatric orthopaedic surgery.

METHODS

Comprehensive Pubmed database searches were performed for all English language articles published between January 2016 and November 2021 using the following search terms: basic science, pediatric orthopaedics, fracture, trauma, spine, scoliosis, DDH, hip dysplasia, Perthes, Legg-Calve-Perthes, clubfoot, and sports medicine. Inclusion criteria focused on basic science studies of pediatric orthopaedic conditions. Clinical studies or case reports were excluded. A total of 3855 articles were retrieved. After removing duplicates and those failing to meet our inclusion criteria, 49 articles were included in the final review.

RESULTS

A total of 49 papers were selected for review based on the date of publication and updated findings. Findings are discussed in the subheadings below. Articles were then sorted into the following sub-disciplines of pediatric orthopaedics: spine, trauma, sports medicine, hip, and foot.

CONCLUSIONS

With this review, we have identified many exciting developments in pediatric orthopaedic trauma, spine, hip, foot, and sports medicine that could potentially lead to changes in disease management and how we think of these processes.

LEVEL OF EVIDENCE

Level V.

Local Administration of Bone Morphogenetic Protein-2 Using a Hydrogel Carrier for Robust Bone Regeneration in a Large Animal Model of Legg-Calvé-Perthes disease

Legg-Calvé-Perthes disease is juvenile idiopathic osteonecrosis of the femoral head (ONFH) that has no effective clinical resolutions. Previously, local injection of bone morphogenetic protein-2 (BMP2) for ONFH treatment showed a heterogeneous bone repair and a high incidence of heterotopic ossification (HO) due to the BMP2 leakage. Here, we developed a BMP2-hydrogel treatment via a transphyseal bone wash and subsequential injection of BMP2-loaded hydrogel. In vivo studies showed that a hydrogel of gelatin-heparin-tyramine retained the BMP2 for four weeks. The injection of the hydrogel can efficiently prevent leakage. With the bone wash, the injected hydrogel had a broad distribution in the head. In vivo studies on pigs revealed that the BMP2-hydrogel treatment produced a homogeneous bone regeneration without HO. It preserved the subchondral contour and restored the subchondral endochondral ossification, although it increased growth plate fusions. In summary, the study demonstrated a promising BMP2-hydrogel treatment for ONFH treatment, especially for teenagers.

Quantitative T2 and T1ρ mapping are sensitive to ischemic injury to the epiphyseal cartilage in an in vivo piglet model of Legg-Calvé-Perthes disease

OBJECTIVE

To determine if the quantitative MRI techniques T2 and T1ρ mapping are sensitive to ischemic injury to epiphyseal cartilage in vivo in a piglet model of Legg-Calvé-Perthes disease using a clinical 3T MRI scanner. We hypothesized that T2 and T1ρ relaxation times would be increased in the epiphyseal cartilage of operated vs contralateral-control femoral heads 1 week following onset of ischemia.

DESIGN

Unilateral femoral head ischemia was surgically induced in eight piglets. Piglets were imaged 1 week post-operatively in vivo at 3T MRI using a magnetization-prepared 3D fast spin echo sequence for T2 and T1ρ mapping and a 3D gradient echo sequence for cartilage segmentation. Ischemia was confirmed in all piglets using gadolinium contrast-enhanced MRI. Median T2 and T1ρ relaxation times were measured in the epiphyseal cartilage of the ischemic and control femoral heads and compared using paired t-tests. Histological assessment was performed on a subset of five piglets.

RESULTS

T2 and T1ρ relaxation times were significantly increased in the epiphyseal cartilage of the operated vs control femoral heads (ΔT2 = 11.9 ± 3.7 ms, 95% CI = [8.8, 15.0] ms, P < 0.0001; ΔT1ρ = 12.8 ± 4.1 ms, 95% CI = [9.4, 16.2] ms, P < 0.0001). Histological assessment identified chondronecrosis in the hypertrophic and deep proliferative zones within ischemic epiphyseal cartilage.

CONCLUSIONS

T2 and T1ρ mapping are sensitive to ischemic injury to the epiphyseal cartilage in vivo at clinical 3T MRI. These techniques may be clinically useful to assess injury and repair to the epiphyseal cartilage to better stage the extent of ischemic damage in Legg-Calvé-Perthes disease.

Minimally Invasive Necrotic Bone Washing Improves Bone Healing After Femoral Head Ischemic Osteonecrosis: An Experimental Investigation in Immature Pigs

BACKGROUND

Ischemic osteonecrosis of the femoral head produces necrotic cell debris and inflammatory molecules in the marrow space, which elicit a chronic inflammatory repair response. The purpose of this study was to determine the effects of flushing out the necrotic cell debris and inflammatory proteins on bone repair in a piglet model of ischemic osteonecrosis.

METHODS

Osteonecrosis of the femoral head of the right hindlimb was induced in 12 piglets by tying a ligature tightly around the femoral neck. One week after the surgery, 6 animals were treated with a percutaneous 3-needle bone washing procedure and non-weight-bearing (NWB) of the right hindlimb (wash group). The total saline solution wash volume was 450 mL per femoral head. Serial wash solutions were collected and analyzed. The remaining 6 animals were treated with NWB only (NWB group). At 8 weeks after the surgery, the femoral heads were assessed using radiography, micro-computed tomography (micro-CT), and histological analysis. In addition, we compared the results for these piglets with our published results for 6 piglets treated with multiple epiphyseal drilling (MED) plus NWB without bone washing (MED group).

RESULTS

Necrotic cells and inflammatory proteins were present in the bone wash solution collected 1 week after ischemia induction. The protein and triglyceride concentrations decreased significantly with subsequent washing (p < 0.005). At 8 weeks after ischemia induction, the wash group had a significantly higher bone volume than the MED or NWB group (p < 0.0001). Histological bone-formation measures were also significantly increased in the wash group compared with the MED group (p = 0.002) or NWB group (p < 0.0001) while macrophage numbers were significantly decreased in the wash group.

CONCLUSIONS

The percutaneous 3-needle procedure flushed out cell debris and inflammatory proteins from the necrotic femoral heads, decreased osteoclasts and macrophages, and increased bone formation following induction of ischemic osteonecrosis.

CLINICAL RELEVANCE

We believe that this is the first study to investigate the concept of washing out the necrotic femoral head to improve bone healing. The minimally invasive procedure may be useful to improve the necrotic bone environment and bone repair following ischemic osteonecrosis.

Anti-Interleukin-6 Therapy Decreases Hip Synovitis and Bone Resorption and Increases Bone Formation Following Ischemic Osteonecrosis of the Femoral Head

Legg-Calvé-Perthes disease (LCPD) is a juvenile form of ischemic femoral head osteonecrosis, which produces chronic hip synovitis, permanent femoral head deformity, and premature osteoarthritis. Currently, there is no medical therapy for LCPD. Interleukin-6 (IL-6) is significantly elevated in the synovial fluid of patients with LCPD. We hypothesize that IL-6 elevation promotes chronic hip synovitis and impairs bone healing after ischemic osteonecrosis. We set out to test if anti-IL-6 therapy using tocilizumab can decrease hip synovitis and improve bone healing in the piglet model of LCPD. Fourteen piglets were surgically induced with ischemic osteonecrosis and assigned to two groups: the no treatment group (n = 7) and the tocilizumab group (15 to 20 mg/kg, biweekly intravenous injection, n = 7). All animals were euthanized 8 weeks after the induction of osteonecrosis. Hip synovium and femoral heads were assessed for hip synovitis and bone healing using histology, micro-CT, and histomorphometry. The mean hip synovitis score and the number of synovial macrophages and vessels were significantly lower in the tocilizumab group compared with the no treatment group (p < .0001, p = .01, and p < .01, respectively). Micro-CT analysis of the femoral heads showed a significantly higher bone volume in the tocilizumab group compared with the no treatment group (p = .02). The histologic assessment revealed a significantly lower number of osteoclasts per bone surface (p < .001) in the tocilizumab group compared with the no treatment group. Moreover, fluorochrome labeling showed a significantly higher percent of mineralizing bone surface (p < .01), bone formation rate per bone surface (p < .01), and mineral apposition rate (p = .04) in the tocilizumab group. Taken together, tocilizumab therapy decreased hip synovitis and osteoclastic bone resorption and increased new bone formation after ischemic osteonecrosis. This study provides preclinical evidence that tocilizumab decreases synovitis and improves bone healing in a large animal model of LCPD. © 2020 American Society for Bone and Mineral Research (ASBMR).

Analysis of Trabecular Microstructure and Vascular Distribution of Capital Femoral Epiphysis Relevant to Legg-Calve-Perthes Disease

Legg-Calve-Perthes disease is characterized by the capital femoral epiphyseal collapse, which occurs more reliably in the anterior quadrant than the more weight-bearing lateral quadrant. The purpose of this study was to determine whether there is a vascular or microstructural predisposition for anterior femoral epiphyseal collapse in Perthes disease. Thirty-two cadaveric proximal femoral epiphyses from 17 subjects (age 4-14 years old) underwent micro-computed tomography at 10-μm resolution. Each quadrant was analyzed for four markers of trabecular architecture: bone volume fraction (BV/TV), trabecular thickness, trabecular separation (TbSp), and trabecular number (TbN). Vascular channels were then mapped in each quadrant, identified by correlating surface topography with cross-sectional imaging. One-way analysis of variance revealed an overall difference between quadrants (p < 0.001) in BV/TV, TbN, and TbSp. However, post hoc analysis revealed there was no significant difference between the anterior and lateral quadrants for any of the four markers of trabecular architecture. Vascular channel mapping illustrated a predominance of vessels in the posterior half of the epiphysis compared to the anterior half (8.7 ± 4.0 vs. 3.4 ± 3.1 vascular channels, p < 0.001). The lack of microstructural differences between the anterior and lateral quadrants, and the predominance of vascular channels in the posterior half of the epiphysis with posteriorly-based medial femoral circumflex and ligamentum teres vessels suggests that the anterior femoral epiphysis may be a relative vascular watershed region, which predisposes it to collapse after the vascular insult of Perthes disease. Clinical significance: Improved understanding of the pathophysiology of anterior femoral epiphyseal collapse may inform future treatments aimed at revascularization. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1784-1789, 2019.