Role of Mesenchymal Stem Cells Densities When Injected as Suspension in Joints with Osteochondral Defects.

OBJECTIVE: The aim of this study was to evaluate an intraarticular injection of different doses of autologous mesenchymal stem cells (MSCs) for improving repair of midterm osteochondral defect. DESIGN: At 4 weeks postoperative marrow stimulation model bilaterally (3 mm diameter; 4 mm depth) in the medial femoral condyle, autologous MSCs were injected into knee joint. Twenty-four Japanese rabbits aged 6 months were divided randomly into 4 groups ( n = 6 per group): the control group and and MSC groups including 0.125, 1.25, and 6.25 million MSCs. Repaired tissue was assessed macroscopically and histologically at 4 and 12 weeks after intraarticular injection of MSCs. RESULTS: At 12 weeks, there was no repair tissue in the control group. The gross appearance of the 1.25 and 6.25 million MSC groups revealed complete repair of the defect with white to pink tissue at 12 weeks. An osteochondral repair was histologically significantly better in the 1.25 and 6.25 million MSC groups than in the control and 0.125 million MSC groups at 4 and 12 weeks, due to presence of hyaline-like tissue in the deep layer at 4 weeks, and at 12 weeks hyaline cartilage formation at the periphery and fibrous tissue containing some chondrocytes in the deep layer of the center of the defect. Subchondral bone was restructured in the 1.25 and 6.25 million MSC groups, although it did not resemble the normal bone. CONCLUSION: An intraarticular injection of 1.25 or 6.25 million MSCs could promote the repair of subchondral bone, even in the case of midterm osteochondral defect.

The Subchondral Bone Is Affected by Bone Marrow Stimulation: A Systematic Review of Preclinical Animal Studies.

OBJECTIVE: Despite the mechanical and biological roles of subchondral bone (SCB) in articular cartilage health, there remains no consensus on the postoperative morphological status of SCB following bone marrow stimulation (BMS). The purpose of this systematic review was to clarify the morphology of SCB following BMS in preclinical, translational animal models. DESIGN: The MEDLINE and EMBASE databases were systematically reviewed using specific search terms on April 19, 2016 based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The morphology of the SCB was assessed using of microcomputed tomography (bone density) and histology (microscopic architecture). RESULTS: Seventeen animal studies with 520 chondral lesions were included. The morphology of SCB did not recover following BMS. Compared with untreated chondral defects, BMS resulted in superior morphology of superficial SCB and cartilage but inferior morphology (specifically bone density, P < 0.05) of the deep SCB. Overall, the use of biological adjuvants during BMS resulted in the superior postoperative morphology of SCB. CONCLUSIONS: Alterations in the SCB following BMS were confirmed. Biologics adjuvants may improve the postoperative morphology of both SCB and articular cartilage. Refinements of BMS techniques should incorporate consideration of SCB damage and restoration. Investigations to optimize BMS techniques incorporating both minimally invasive approaches and biologically augmented platforms are further warranted.

Healing of Osteochondral Defects via Endochondral Ossification in an Ovine Model.

OBJECTIVE: The objective of this study was to describe the mechanism of healing of osteochondral defects of the distal femur in the sheep, a commonly used translational model. Information on the healing mechanism be useful to inform the design of tissue engineering devices for joint surface defect repair. DESIGN: A retrospective study was conducted examining 7-mm diameter osteochondral defects made in the distal medial femoral condyle of 40 adult female sheep, comprising control animals from 3 separate structures. The healing of the defects was studied at post mortem at up to 26 weeks. RESULTS: Osteochondral defects of the distal femur of the sheep heal through endochondral ossification as evidenced by chondrocyte hypertrophy and type X collagen expression. Neocartilage is first formed adjacent to damaged cartilage and then streams over the damaged underlying bone before filling the defect from the base upward. No intramembranous ossification or isolated mesenchymal stem cell aggregates were detected in the healing tissue. No osseous hypertrophy was detected in the defects. CONCLUSIONS: Osteochondral defects of the medial femoral condyle of the sheep heal via endochondral ossification, with neocartilage first appearing adjacent to damaged cartilage. Unlike the mechanism of healing in fracture repair, neocartilage is eventually formed directly onto damaged bone. There was most variability between animals between 8 and 12 weeks postsurgery. These results should be considered when designing devices to promote defect healing.

Treatment of large deep osteochondritis lesions of the knee by autologous matrix-induced chondrogenesis (AMIC): Preliminary results in 13 patients.

BACKGROUND: Osteochondral defects due to advanced osteochondritis of the knee eventually cause osteoarthritis. Autologous matrix-induced chondrogenesis (AMIC) may hold potential for overcoming the treatment challenges raised by defects larger than 2cm2. The primary objective of this study was to assess medium-term functional outcomes of AMIC. The secondary objective was to confirm the absence of adverse events. HYPOTHESIS: AMIC significantly improves knee function in patients with osteochondritis responsible for osteochondral defects grade III or IV in the International Cartilage Repair Society (ICRS) classification. MATERIAL AND METHODS: A total of 13 consecutive patients managed using AMIC between September 2011 and November 2016 were included in a prospective, single-centre, single-surgeon study. There were 8 males and 5 females with a mean age of 29 years (range, 15-51 years). Among them, 9 had had previous surgery. The ICRS grade was IV in 12 patients and III in 1 patient. The defects had a mean surface area of 3.7cm2 (range, 2.2-6.9cm2) and mean depth of 0.5mm (range, 0.4-0.8). In each patient, knee function was assessed by an independent examiner based on validated instruments (Knee injury and Osteoarthritis Outcome Score [KOOS], subjective International Knee Documentation Committee [IKDC] score, and visual analogue scale [VAS] pain score). RESULTS: After a median follow-up of 24 months (range, 12-42 months; minimum, 1 year), 11 patients had significant improvements, with mean increases in the IKDC score and KOOS of 27 and 28 points, respectively. The scores remained stable after the first year. Of the 2 patients with poorer outcomes, 1 had a history of multiple surgical procedures and the other was a 51-year-old female with a defect surface area of 6.9cm2. No post-operative complications were recorded. CONCLUSION: AMIC is a reliable single-stage method that is both reproducible and widely available. AMIC significantly improves knee function scores in patients with large osteochondral defects due to advanced osteochondritis of the knee. LEVEL OF EVIDENCE: IV, prospective cohort study.

Osteochondral lesions of the talus.

Background and purpose - The frequency of progression of osteoarthritis and persistence of symptoms in untreated osteochondral lesion of the talus (OCL) is not well known. We report the outcome of a nonoperative treatment for symptomatic OCL. Patients and methods - This study included 142 patients with OCLs from 2003 to 2013. The patients did not undergo immobilization and had no restrictions of physical activities. The mean follow-up time was 6 (3-10) years. Initial MRI and CT confirmed OCL and showed lesion size, location, and stage of the lesion. Progression of osteoarthritis was evaluated by standing radiographs. In 83 patients, CT was performed at the final follow-up for analyses of the lesion size. We surveyed patients for limitations of sports activity, and Visual Analogue Scales (VAS), AOFAS, and SF-36 were assessed. Results - No patients had progression of osteoarthritis. The lesion size as determined by CT did not change in 69/83 patients, decreased in 5, and increased in 9. The mean VAS score of the 142 patients decreased from 3.8 to 0.9 (p < 0.001), the mean AOFAS ankle-hindfoot score increased from 86 to 93 (p < 0.001), and the mean SF-36 score increased from 52 to 72 (p < 0.001). Only 9 patients reported limitations of sports activity. The size and location of the lesion did not correlate with any of the outcome scores. Interpretation - Nonoperative treatment can be considered a good option for patients with OCL.

Prevalence of Vitamin D Deficiency in Patients With Talar Osteochondral Lesions.

BACKGROUND: Vitamin D deficiency affects over 1 billion people worldwide and is common in foot and ankle patients. The prevalence in those with osteochondral lesions of the talus (OLTs) is unknown. This study identified the prevalence and risk factors for hypovitaminosis D in patients with an OLT. METHODS: Serum 25(OH)D levels were obtained from patients presenting with an OLT from May to November during 2007 to 2016. Hypovitaminosis D was defined as 25(OH)D less than 30 ng/mL (75 nmol/L). Patients presenting with an acute ankle sprain (AS) during the same months served as a control group. Specific medical risk factors for hypovitaminosis D were recorded. The final OLT population included 46 patients (31 women [67.4%]; mean [SD] age 43.6 [14.8] years). The comparison AS group had 40 patients (32 women [80.0%]; mean [SD] age 56.2 [13.0] years). RESULTS: The mean (SD) 25(OH)D in the OLT and AS cohorts were 31.2 (12.6) ng/mL and 37.1 (13.5) ng/mL, respectively ( P = .039). Hypovitaminosis D was identified in 54% of the OLT population and 28% of the AS population ( P = .012). CONCLUSION: Hypovitaminosis D is intimately related to decreased bone mineral density. This study identified a significantly higher rate of hypovitaminosis D in patients with an OLT compared to a cohort of AS patients. These findings suggest that when patients present with an OLT, health care providers should consider evaluating for and treating hypovitaminosis D. LEVEL OF EVIDENCE: Level III, comparative study.

Enfermedad de Van Neck-Odelberg: una causa más de cojera en la infancia / Van Neck-Odelberg disease: a cause of limp in childhood

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A bioinformatic analysis of microRNAs role in osteoarthritis.

OBJECTIVE: To evaluate the underlying function of microRNAs (miRNAs) in osteoarthritis (OA). DESIGN: A bioinformatic analysis of miRNAs-OA studies was completed in multiple databases. All identified articles were assessed using specific inclusion and exclusion criteria (Eligible case-control studies for the present study included those which investigated miRNAs differential expression in cartilage tissues and cells of OA and controls. Abstracts, case reports, conference presentations, editorials, and expert opinions were excluded.). We performed bioinformatic analysis and assessed which miRNAs are commonly elevated or decreased in cartilage of OA, and assessed putative targets of these miRNAs using TargetScan, Database for Annotation, Visualization and Integrated Discovery (DAVID), FunRich and String. RESULTS: Fifty seven studies were included in this study. Our current review has identified 46 differentially expressed miRNAs involved in autophagy, inflammation, chondrocyte apoptosis, chondrocyte differentiation & homeostasis, chondrocyte metabolism and degradation of the extracellular matrix (ECM). Additionally, our literature search identified a wide range of miRNAs that have been shown to be differentially expressed in OA. The function of up-regulated miRNAs primarily target nucleus, whereas the function of down-regulated miRNAs primarily target transcription. CONCLUSIONS: Comprehensive analysis of all miRNAs studies reveals cooperation in miRNA signatures and suggests that there may be two biologically synergic classes of miRNAs that are associated with OA. This finding suggests that miRNAs may be useful as diagnostic biomarkers and/or may provide new therapeutic targets in OA. Furthermore, a better understanding of the targets of these miRNAs will accelerate biomedical discoveries and improve clinical care based on new knowledge of OA-related disease mechanisms.

Clinical and MRI Donor Site Outcomes Following Autologous Osteochondral Transplantation for Talar Osteochondral Lesions.

BACKGROUND: Autologous osteochondral transplantation (AOT) has an inherent risk of donor site morbidity (DSM). The reported rates of DSM vary from 0% to 50%, with few studies reporting clinical or imaging outcomes at the donor site as a primary outcome and even fewer report these outcomes when a biosynthetic plug backfill is employed. Although TruFit (Smith & Nephew, Andover, MA) plugs have been removed from the market for regulatory purposes, biphasic plugs (including TruFit plugs) have been used for several years and the evaluation of these is therefore pertinent. METHODS: Thirty-nine patients who underwent forty AOT procedures of the talus, with the donor graft being taken from the ipsilateral knee, were included. Postoperative magnetic resonance imaging (MRI) was used to assess the donor site graded with magnetic resonance observation of cartilage repair tissue (MOCART) scoring. Lysholm scores were collected preoperatively, at the time of magnetic resonance imaging (MRI), and again at 24 months and at final follow-up to assess clinical outcomes. Statistical analysis was performed to establish if there was any correlation between MRI assessment of the donor site and clinical outcomes. The mean patient age was 36.2 ± 15.7 years with a mean follow-up of 41.8 ± 16.7 months. RESULTS: All patient donor site defects were filled with OBI TruFit biphasic plugs. DSM was encountered in 12.5% of the patient cohort at 24 months, and in these patients, the Lysholm score was a mean 87.2 ± 5.0. At final follow-up, DSM was reduced to 5%. Lysholm scores for the entire cohort were 98.4 ± 4.6 and 99.4 ± 3.1 at 24 months and final follow-up, respectively. MRI of the donor sites were taken at an average of 18.1 ± 13.5 (range, 3-48) months postoperatively and the mean MOCART score was 60.0 ± 13.5. No correlation was found between the MOCART score and Lysholm outcomes at the donor knee (P = .43, r = 0.13). CONCLUSION: Low incidence of DSM and good functional outcomes were achieved with AOT. Additionally, MRI findings did not predict clinical outcomes in our study. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Long-term results of microfracture in the treatment of talus osteochondral lesions.

PURPOSE: Osteochondral lesions of the talus are common injuries, and many clinicians consider arthroscopic debridement and microfracture as the first-stage treatment. This study assessed the long-term clinical and radiographic outcomes of arthroscopic debridement and microfracture for osteochondral lesions of the talus. METHODS: A total of 82 patients (48 males, 34 females) who were treated with arthroscopic debridement and microfracture for osteochondral lesions of the talus between 1996 and 2009 with a minimum 5-year follow-up were included in our study group. Functional scores (AOFAS, VAS) and ankle range of motion were determined, and an arthrosis evaluation was performed. Subgroup evaluations based on age, lesion localization, and defect size were performed using functional outcome correlations. RESULTS: The mean age of the patients was 35.9 ± 13.4 years (14-69 years), and the mean follow-up period was 121.3 months (61-217 months). The mean defect size was 1.7 ± 0.7 cm2 (0.25-5). The mean pre-operative AOFAS score was 58.7 ± 5.2 (49-75), and the mean post-operative AOFAS score was 85.5 ± 9.9 (56-100). At the last follow-up, 35 patients (42.6%) had no symptoms and 19 patients (23.1%) had pain after walking more than 2 h or after competitive sports activities. Radiological assessments of arthrosis revealed that no patient had grade 4 arthritis but that 27 patients (32.9%) had a one-stage increase in their arthrosis level. Subgroup analyses of the lesion location demonstrated that lateral lesions had significantly better functional results (p = 0.02). CONCLUSIONS: Arthroscopic debridement and microfracture provide a good option for the treatment of osteochondral lesions of the talus over the long term in select patients. Functional outcomes do not correlate with defect size or patient age. Orthopaedic surgeons should adopt the microfracture technique, which is minimally invasive and effective for treating osteochondral lesions of the talus. LEVEL OF EVIDENCE: IV.

Lift, drill, fill and fix (LDFF): a new arthroscopic treatment for talar osteochondral defects.

PURPOSE: The purpose of this study was to describe the short-term clinical outcome of a new arthroscopic fixation technique for primary osteochondral talar defects: lift, drill, fill and fix (LDFF). METHODS: Seven patients underwent an arthroscopic LDFF surgery for osteochondral talar defects, the mean follow-up was 12 months (SD 0.6). Pre- and postoperative clinical assessment included the American Orthopaedic Foot and Ankle Society Score (AOFAS) and the numeric rating scales (NRS) of pain at rest and during walking. Remodelling and bone ingrowth after LDFF were analysed on weight-bearing radiographs during follow-up. RESULTS: In all patients, LDFF led to an improvement of the AOFAS and NRS of pain. The AOFAS significantly improved from 63 to 99 (p < 0.001). The NRS of pain at rest significantly improved from 2.9 to 0.1 (p = 0.004), and pain with walking significantly improved from 7.6 to 0.1 (p < 0.001). On the final radiographs, five of seven patients showed remodelling and bone ingrowth after LDFF. CONCLUSIONS: The LDFF of an osteochondral talar defect appears to be a promising arthroscopic treatment option for primary talar osteochondral defects. Although the clinical and radiological results of 1-year follow-up are encouraging, more patients and longer follow-up are needed to draw any firm conclusions and determine whether the results stand the test of time. LEVEL OF EVIDENCE: Prospective case series. Therapeutic, Level IV.

Autologous osteochondral transplantation for osteochondral lesions of the talus in an athletic population.

PURPOSE: To assess clinical outcomes and return to sport in an athletic population treated with autologous osteochondral transplantation (AOT) for osteochondral lesions of the talus. METHODS: A total of 36 patients were included in this retrospective study including 21 professional athletes and 15 amateur athletes who participated in regular moderate- or high-impact athletic activity. All patients underwent autologous osteochondral transplantation of the talus under the care of a single surgeon. At a mean follow-up of 5.9 years, patients were assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) scoring system. All patients also received pre-operative MRI with the follow-up MRI performed at 1 year and underwent assessment of return to athletic activity. RESULTS: The overall AOFAS score improved from 65.5 (SD ± 11.1) to 89.4 (SD ± 14.4) (p = 0.01). At a final follow-up, 90% of professional athletes (19 of 21) were still competing in athletic activity or still able to participate in unrestricted activity. Of the recreational athletes, 87% (13 of 15) had full return to pre-injury activity levels, while two (13%) returned to activity with restrictions or reduced intensity. MRI showed cystic change in 33% of patients post-operatively; however, this did not appear to affect outcomes (n.s.). Donor site symptoms were seen in 11% of the cohort at final follow-up, despite high function at donor knee. CONCLUSION: The results of our study indicate that AOT procedure is able to achieve good outcomes in an athletic population at a midterm follow-up. LEVEL OF EVIDENCE: Retrospective case series, Level IV.

Medium-term outcomes of mosaicplasty versus arthroscopic microfracture with or without platelet-rich plasma in the treatment of osteochondral lesions of the talus.

PURPOSE: This study aimed to compare medium-term functional effects of three different treatment modalities in patients with osteochondral lesions of the talus (OLT). METHODS: Fifty-four patients undergoing arthroscopic surgery for osteochondral lesion of the talus were included in this study. Patients were assigned to one of the three treatment groups: microfracture surgery (n = 19), microfracture surgery plus platelet-rich plasma (PRP) (n = 22), and mosaicplasty (n = 13). Function was assessed using the American Orthopedic Foot and Ankle Society (AOFAS) scoring system and VAS scores for pain, before and after surgery. In addition, the Foot and Ankle Ability Measure (FAAM) tests for pain and 15-min walking were done at follow-up visits. RESULTS: The median duration of follow-up was 42 months (range 12-84 months). All groups showed significant improvements in AOFAS and VAS pain scores at the last follow-up visit, when compared to baseline. The groups did not differ with regard to change in baseline AOFAS score; however, improvement in VAS pain scores was significantly better in the mosaicplasty group when compared to the microfracture group (change from baseline, -5.8 ± 1.0 vs. -3.2 ± 2.9, p = 0.018). CONCLUSIONS: All the three treatment modalities resulted in good medium-term functional results. However, mosaicplasty procedure seems to be a promising option and it might be preferred particularly in patients where pain control is important. LEVEL OF EVIDENCE: II.

High incidence of osteochondral lesions after open reduction and internal fixation of displaced ankle fractures: Medium-term follow-up of 100 cases.

BACKGROUND: The incidence of osteochondral lesions (OCLs) in association with displaced ankle fractures has only been examined in two previous studies. In both studies magnetic resonance imaging (MRI) was performed prior to open reduction and internal fixation (ORIF). Because MRI may overdiagnose or overestimate the extent of OCLs in an acute trauma setting the aim of this study was to determine the incidence of OCLs after ORIF of displaced ankle fractures using MRI at medium-term follow-up, and to analyse if the severity of fracture or the clinical outcome correlates with the incidence of OCLs. PATIENTS AND METHODS: Following institutional review board approval a total of 100 patients (mean age, 41.3 years; range, 17.9-64.3 years) with a displaced ankle fracture who had undergone ORIF according to the AO principles were included in this study. The American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score was used to quantify the clinical outcome and MR images were evaluated for OCLs of the talus and distal tibia after a mean of 34.5 months (range, 17.5-54.1 months). RESULTS: OCLs were found in 40.4% of the patients. Logistic regression revealed a significant correlation between the severity of fracture and the incidence of OCLs. Patients with a trimalleolar fracture (p=0.04) or an ankle fracture dislocation (p=0.003) had a significantly higher risk for developing an OCL compared to those with a type B fracture. Logistic regression also demonstrated a significant correlation between the clinical outcome (AOFAS score) and the incidence of OCLs (p=0.01). The risk for developing an OCL increases up to 5.6% when the AOFAS score decreases by one point. CONCLUSION: OCLs were frequently found in association with acute ankle fractures at medium-term follow-up, and the severity of fracture was associated with an increased number of OCLs. Considering the disadvantages of MRI including the high cost and limited availability, the results of this study may help to explain why anatomic surgical realignment of displaced ankle fractures may still be associated with poor clinical outcomes.

Treatment of Freiberg's disease by Gauthier's dorsal cuneiform osteotomy: Retrospective study of 30 cases.

INTRODUCTION: Freiberg's disease is osteonecrosis of the dorsal side of a metatarsal head. The gold-standard surgical treatment is the osteotomy procedure first described by Gauthier. HYPOTHESIS: Gauthier osteotomy for Freiberg's disease will restore the joint space and lead to long-term clinical improvement. A retrospective study was carried out to verify this hypothesis. MATERIAL AND METHODS: This study involved 30 consecutive cases treated by a single surgeon in 28 patients having a mean age of 61.2 years. These patients underwent the Gauthier osteotomy procedure with one or two dorsal staples used for fixation. Patients were reviewed 15 days, 45 days and 3 months after the procedure, and then at the last follow-up to look for any complications and determine patient satisfaction, the AOFAS score, metatarsophalangeal range of motion (ROM), sphericity of the metatarsal head, bone union and metatarsal shortening. RESULTS: The average follow-up was 6.5 years ± 2.2. The second metatarsal was affected in 27 cases and the third metatarsal in 3 cases. Discomfort related to the staples was noted in five cases; the staples were removed in three of them. There was one case of severe stiffening (< 20° ROM). At the last follow-up, 17 cases were very satisfied, 11 were satisfied and 2 were moderately satisfied. The average AOFAS score was 83.8 points ± 11.8 at the last follow-up. A mean loss of 15° plantar flexion and 10° dorsiflexion was noted. Bone union and metatarsal head sphericity were achieved in all cases. The average shortening was 2 mm ± 1.4. CONCLUSIONS: The Gauthier osteotomy procedure results in recovery of the metatarsal head's sphericity in every case of this series, with good clinical results and low morbidity.

Osteochondral lesion of the hip treated with partial femoral head resurfacing. Case report and six-year follow-up.

INTRODUCTION: This case describes a case of an osteochondral lesion in the femoral head and its treatment by partial resurfacing of the femoral head using the HemiCAP (Contoured Articular Prosthetic) hip resurfacing system. CASE HISTORY: A 19-year-old patient who complained of 15 months of worsening left hip pain. X-rays and MR scan revealed a large osteochondral lesion. SURGERY: A Ganz approach to the hip in the lateral position was used. The osteochondral lesion was identified, lying superiorly and centrally on the head, in the weight bearing zone. The osteochondral fragment was removed and HemiCAP prosthesis applied. OUTCOME: At six-year follow-up the patient remains pain free clinically. And radiographic follow-up shows no evidence of loosening. CONCLUSION: There are multiple methods of treatment described in the literature for osteochondral lesions; but treatments for defects of the femoral head are few. We conclude that partial hip resurfacing using the HemiCAP prosthesis is an effective treatment for osteochondral defects of the femoral head.

Static and dynamic plantar pressures in children with and without sever disease: a case-control study.

BACKGROUND: Calcaneal apophysitis (Sever disease) has been reported to be the most common cause of heel pain in athletic children. OBJECTIVE: The study aim was to compare plantar pressure, plantar surface contact area, distribution of body weight across the lower extremities, and prevalence of gastrocnemius ankle equinus and gastrocnemius-soleus ankle equinus (which can cause decreases in ankle dorsiflexion range of motion) in children with and without Sever disease. DESIGN: This was a case-control study. METHODS: Participants were 56 male students enrolled in a soccer academy. Twenty-eight participants had Sever disease (Sever disease group), and 28 participants were healthy (control group). Dynamic and static peak plantar pressures, plantar surface contact area, and body weight distribution were assessed with pedobarography. A goniometer was used to assess gastrocnemius and gastrocnemius-soleus ankle dorsiflexion range of motion. RESULTS: Both maximum and average peak pressures and percentages of body weight supported by each heel were significantly higher in the symptomatic feet of participants in the Sever disease group than in the control group. Twenty-six participants with Sever disease but only 8 participants in the control group exhibited bilateral gastrocnemius ankle equinus. LIMITATIONS: A limitation of the study is that measurements were obtained from participants who were symptomatic. CONCLUSIONS: Higher heel plantar pressures under dynamic and static conditions appear to be associated with Sever disease. It is unclear, however, whether these higher pressures are a predisposing factor contributing to the disease or a result of the condition. Gastrocnemius ankle equinus also may be a predisposing factor for Sever disease. Further research is needed to identify other biomechanical factors associated with the disease to enhance prevention and treatment strategies.