Restoration of Native Leg Length After Opening-Wedge High Tibial Osteotomy: An Intraindividual Analysis

Background: Opening-wedge high tibial osteotomy (OWHTO) has been shown to significantly increase leg length, especially in patients with large varus deformity. Thus, the current literature recommends closing-wedge high tibial osteotomy to correct malalignment in these patients to prevent postoperative leg length discrepancy. However, potential preoperative leg length discrepancy has not been considered yet. Hypothesis: It was hypothesized that patients have a decreased preoperative length of the involved leg compared with the contralateral side and that OWHTO would subsequently restore native leg length. Study Design: Case series; Level of evidence, 4. Methods: Included were 67 patients who underwent OWHTO for unilateral medial compartment knee osteoarthritis and who received full leg length assessment pre- and postoperatively. Patients with varus or valgus deformity (>3°) of the contralateral side were excluded. A musculoskeletal radiologist assessed imaging for the mechanical axis, full leg length, and tibial length of the involved and contralateral lower extremity. Statistical analysis determined the pre- and postoperative leg length discrepancy and the influence of the mechanical axis. Results: Most patients (62.7%) had a decreased length of the involved leg, with a mean preoperative mechanical axis of 5.0° ± 2.9°. Length discrepancy averaged –2.2 ± 5.8 mm, indicating a shortened involved extremity ( P = .003). OWHTO significantly increased the mean lengths of the tibia and lower limb by 3.6 ± 2.9 and 4.4 ± 4.7 mm ( P < .001), leading to a postoperative tibial and full leg length discrepancy of 2.8 ± 4.3 mm and 2.2 ± 7.3 mm ( P < .001 and P = .017, respectively). Preoperative leg length discrepancy was significantly correlated with the preoperative mechanical axis of the involved limb ( r = 0.292; P = .016), and the amount of correction was significantly associated with leg lengthening after OWHTO ( r = 0.319; P = .009). Patients with a varus deformity of ≥6.5° (n = 14) had a preoperative length discrepancy of –4.5 ± 1.6 mm ( P < .001) that was reduced to 1.8 ± 3.5 mm ( P = .08). Conclusion: Patients undergoing OWHTO have a preoperative leg length discrepancy that is directly associated with the varus deformity of the involved extremity. As OWHTO significantly increases leg length, restoration of native leg length can be achieved particularly in patients with large varus deformity.

Surgical Treatment of Leg Length Discrepancy and Knee Flexion Contracture Associated with a Congenital Absence of Quadriceps

We report the case of an 18-year-old male with congenital absence of quadriceps and hypoplasia of the patella who presented with a significant leg length discrepancy (LLD) and knee flexion contracture. Surgical management was aimed toward lengthening the limb, stabilizing the joint, and correcting the knee flexion contracture. Correction of a significant congenital LLD and knee flexion contracture poses challenges due to long-standing altered biomechanics. These are rare conditions for which no accepted surgical algorithms exist. It is essential to anticipate the biomechanical consequences of limb lengthening and flexion contracture correction that might arise and plan comprehensive interventions accordingly.

Guided Growth in Leg Length Discrepancy in Beckwith-Wiedemann Syndrome: A Consecutive Case Series

Beckwith-Wiedemann Syndrome (BWS) is a rare genetic disorder characterized by overgrowth, macroglossia, abdominal wall defects, neonatal hypoglycemia, predisposition to embryonal tumor, lateralized overgrowth, and leg length discrepancy (LLD), which can affect normal posture and gait. Aim of this study was to evaluate the effects of guided growth (temporary epiphysiodesis technique) as LLD management in BWS patients. Between 2007 and 2021, 22 BWS patients (15 F, 7 M) with a mean age of 7.9 years (2.9–14.4) and a mean LLD at first surgery of 3.65 cm (2–10), underwent temporary proximal tibial (PTE) and distal femur epiphysiodesis (DFE). In 18 patients the first surgical procedure was PTE, in one, DFE, and in 3 cases, PTE and DFE at the same time, respectively. Eleven patients reached equality of leg length after a mean follow-up of 7.7 years (3.7–13.0) and mean age of 13.3 years (12.7–27.5); 10 patients underwent 3 surgical procedures, one 7 procedures. Fifteen patients had no complications. No severe complications, infection, articular stiffness, or neuro-vascular lesions occurred in remaining patients; complications included secondary varus or valgus axial deviation in a total of 6 patients, and two screw breakages in two patients. Guided growth as a minimally invasive procedure seems efficient for LLD treatment with low complication rate in BWS patients.

Targeted Next Generation Sequencing Expands Genotype in Patients with PIK3CA-Related Overgrowth Spectrum (PROS)

Background: Disorders of somatic mosaicism (DoSM) are caused by mutations that arise post-zygotically and are present in only a specific part of the body. These mutations alter the function and regulation of key genes in cell proliferation pathways, including the PI3K/AKT/mTOR pathway, and show significant overlap with mutations identified in cancer(McNulty et al. Am J Hum Genet, 2019). PIK3CA-Related Overgrowth Spectrum (PROS) is an umbrella term that encompasses a variety of overgrowth syndromes caused by post-zygotic, somatic gain-of-function PIK3CA mutations with low-level mosaicism (Luks et al. J Pediatr, 2015). The clinical phenotype of PROS is heterogeneous and many tissue types can be affected. This often makes clinical diagnosis challenging. The use of cancer genomics in patients with vascular anomalies may aid in establishing a genetic diagnosis and expand use of targeted medical therapies. Methods: Three patients who presented with clinical symptoms of PROS underwent targeted next generation sequencing of affected tissue using OncoPanel. Oncopanel is a genomic assay that detects somatic mutations, copy number variations and structural variants in 447 genes implicated in cancer. Results: Three patients with a PROS phenotype demonstrated somatic mutations in genes distinct from PIK3CA. Case 1: A 15-year-old female presented with a painful right leg mass, calf atrophy, contracture of the knee, leg-length discrepancy, and severe limp. Histology was consistent with fibroadipose vascular anomaly (FAVA) versus kaposiform hemangioendothelioma (KHE). Given her significant functional impairment, treatment with Sirolimus was initiated with significant improvement in appearance and functionality. OncoPanel testing revealed a PIK3C2B c.2881G&gt;A (p.G961S) mutation. Case 2: A 12-month-old male was noted at birth to have a diffuse capillary malformation, multiple lymphatic malformations, macrodactyly of his bilateral hands and leg length-discrepancy, consistent with Congenital Lipomatous Overgrowth, Vascular Malformations, Epidermal Nevi, Spinal/Skeletal Anomalies/Scoliosis (CLOVES) syndrome. He underwent numerous surgical de-bulking procedures, epiphysiodesis, sclerotherapy, and laser therapy with continued disease progression. OncoPanel revealed a PIK3R1c.1731_1738delAGACCAATinsATGTAAGAAAG (p.D578_Y580delinsCKKD) mutation. Case 3: A 10-month-old female presented with a diffuse capillary malformation and leg-length discrepancy. She subsequently developed multiple painful and progressive lymphatic lesions over her left arm and chest which did not respond to sclerotherapy. Due to high clinical suspicion for PROS, she underwent targeted genetic testing via droplet digital PCR (ddPCR) to detect the five most common variants (C420R, E542K, E545K, H1047L, H1047R) in PIK3CA, but no hotspot mutations were identified. Over the next year and a half, the patient had two biopsies performed, PIK3CA ddPCR testing performed twice, and OncoPanel testing performed twice. OncoPanel testing of the second tissue biopsy ultimately resulted in the identification of a PIK3R1 c.1723-1731del p.K575_R577del mutation. Conclusion: The clinical diagnosis of DoSM is often challenging. While the use of cancer genomics for diagnostic purposes in vascular anomalies is uncommon, its use continues to broaden our understanding of syndromes related to alterations in the PI3K/AKT/mTOR pathway. PIK3CB encodes a catalytic subunit of PI3K, p110β, and is dysregulated in certain types of cancer. PIK3R1 encodes multiple regulatory subunits of PI3K and acts as a negative regulator of PIK3CA function. Both gain-of-function of PIK3CB or loss-of-function of PIK3R1 lead to inappropriate activation of PIK3CA, and our cases highlight that mutations in other genes can lead to the clinical phenotype of PROS. It is reasonable to expect that patients with alterations in genes that activate PIK3CA may benefit from medical treatment with direct PIK3CA inhibitors. Limiting diagnostic testing to evaluation of the PIK3CA gene alone may yield negative results and preclude patient eligibility for treatment with novel therapies. The use of next-generation sequencing (NGS) designed to detect somatic variations in cancer will likely play a pivotal role in detecting variants in vascular anomalies in the future and in expanding our understanding of genetic alterations involved in PROS. Disclosures No relevant conflicts of interest to declare. OffLabel Disclosure: Sirolimus is used off-label for the treatment of vascular anomalies.