Factors Affecting Postoperative Courses After Removal of Transphyseal Screws Inserted for Correction of Genu Valgum.

BACKGROUND: The aim of this study was to investigate factors determining the final outcomes of hemipercutaneous epiphysiodesis using transphyseal screw (PETS) for the genu valgum, especially focusing on postoperative courses after screw removal. METHODS: Fifty-five patients with idiopathic genu valgum treated with hemi-PETS were included. The mechanical lateral distal femoral angle (mLDFA) and medial proximal tibial angle (MPTA) were measured to calculate the degree of correction and rebound. Regarding factors related to surgical techniques, the number of screw threads beyond the physis, the moment arm of the screw, and screw insertion angles were measured. RESULTS: In 54 femoral segments (randomly selected in bilateral cases), hemi-PETS was performed with a growth remaining of 2.0±0.6 years. The screw was removed after 6.5±2.1 months, and the degree of correction was 5.0±1.5 degrees. The mean rebound angle was -0.4±2.4 (the negative value means further correction after screw removal). A late time of surgery and an extreme peripheral position of a screw were associated with the growth inhibition. In 50 tibial segments (also randomly selected in bilateral cases), a screw was inserted with a growth remaining of 2.0±0.6 years and removed after 6.3±1.9 months. The degree of correction was 2.9±1.7 degrees during the interval, and the rebound angle was 0.8±1.7 degrees. An earlier time of surgery and a greater correction angle before screw removal were associated with the rebound phenomenon. CONCLUSIONS: Growth inhibition of >1.6 degrees was observed in about one-fourth of femoral segments. An extreme peripheral position of a screw should be avoided when performing hemi-PETS at the distal femur. We also recommend not performing hemi-PETS at distal femur with too short a period of growth remaining. LEVEL OF EVIDENCE: Level III-retrospective comparative series.

Factors Affecting Rebound Phenomenon After Temporary Hemiepiphysiodesis and Implant Removal for Idiopathic Genu Valgum in Adolescent Patients.

BACKGROUND: The aim of this study was to investigate factors determining postoperative courses, especially focusing on the rebound phenomenon, in adolescent patients with idiopathic genu valgum who underwent temporary hemiepiphysiodesis and implant removal. METHODS: We identified and reviewed patients with idiopathic genu valgum treated with temporary hemiepiphysiodesis [using tension-band plates (plate group, PG) or transphyseal screws (screw group, SG)] and followed-up to skeletal maturity. RESULTS: In our cohort [68 patients and their 68 limbs (randomly selected in bilateral cases)], the mean hip-knee-ankle alignment was -5.4±1.8 degrees at the time of temporary hemiepiphysiodesis (negative means valgus), 2.6±2.1 degrees at the time of implant removal, and 0.7±2.6 degrees at the last follow-up, respectively. Regarding the implants, the correction speed was not significantly different (P=0.192-0.315) between the PG (total 1.29±0.37 degrees/mo, 0.71±0.23 degrees/mo at distal femur, 0.59±0.16 degrees/mo at proximal tibia, n=19) and the SG (total 1.22±0.49 degrees/mo, 0.65±0.25 degrees/mo at distal femur, 0.57±0.23 degrees/mo at proximal tibia, n=49). The magnitude of rebound phenomenon in the PG (4.1±1.9 degrees) was greater (P<0.001) than that in the SG (1.1±3.1 degrees). The use of plates and faster correction speed, rather than more severe preoperative deformity or greater correction angle, were positively associated with the rebound phenomenon in regression analyses. Among the 68 knees, 1 showed valgus alignment ≥5 degrees and 5 showed varus alignment ≥5 degrees at the last follow-up. All the 6 cases were observed in the SG. Surgical wound dehiscence was observed in 1 patient in the PG. CONCLUSIONS: The use of plates and faster correction speed were positively associated with the rebound phenomenon. Careful attention will be needed with the corresponding conditions for optimal results. Progressive genu varum after transphyseal screw removal, which was observed in this study, should be explored in future research. LEVEL OF EVIDENCE: Level III-retrospective comparative series.

Predictors of ideal outcomes after reconstructive surgery for chronic Monteggia fracture in children.

BACKGROUND: We aimed to analyze surgical outcomes of reconstructive surgery for chronic Monteggia fracture, which is one of the most challenging problems for orthopaedic surgeons. METHODS: Twenty-eight patients were followed during 55.6 ± 32.0 months after open reduction of the radial head combined with ulnar osteotomy and annular ligament reconstruction. The mean interval from trauma was 15.1 ± 19.6 months, and the mean age at the surgery was 9.1 ± 3.5 years. In addition to the chronological age, elbow maturity was assessed using the Sauvegrain score. Surgical outcomes were primarily evaluated using the Kim's score. In addition, we newly defined more successful criteria for the ideal surgical outcomes, equivalent to preinjury status. RESULTS: There were 19 excellent, 3 good, 4 fair, and 2 poor outcomes based on the Kim's scoring system. Among the 19 patients with excellent outcomes, 14 met our criteria for the ideal outcomes. The age (p < 0.001) and the Sauvegrain score (p < 0.001) were lower, and the interval (p = 0.004) was shorter in 14 patients with ideal outcomes. There were 9 patients with preoperative deformation of the radial head, and all of them showed non-ideal outcomes. In regression analyses, lower Sauvegrain score (p = 0.004) and shorter interval (p = 0.012) were associated with higher postoperative Kim's score, and lower Sauvegrain score (p = 0.031) was related to the achievement of the ideal outcomes. With the Sauvegrain score of >21.5, all patients had postoperative re-dislocation or osteoarthritic changes regardless of the interval. With the Sauvegrain score of <21.5 and an interval of ≤7 months, the ideal outcomes were achieved in 85.7%, and no patients had postoperative re-dislocation or osteoarthritic changes. CONCLUSION: Over the skeletal ages of 14 years in boys and 11.5 years in girls, reconstructive surgery must be cautiously indicated. Under these skeletal ages with an interval of ≤7 months and undeformed radial head, it appears to be ideal. STUDY DESIGN: Level III, Retrospective comparative study.

Difficulties During Ponseti Casting for the Treatment of Idiopathic Clubfoot.

The Ponseti method has resulted in excellent outcomes in the treatment of idiopathic clubfoot. To evaluate the process of serial casting, most studies previously used the number of casts required to achieve correction. In contrast, difficulties that occurred during serial casting were rarely studied. We reviewed 47 patients with severe idiopathic clubfoot (Dimeglio score ≥10) and a follow-up period of ≥4 years by focusing on difficulties during the Ponseti casting and their related factors. All events requiring temporary discontinuation and/or delay of scheduled casting were considered difficulties. Among the 47 patients, difficulties occurred in 18 patients (38.3%). Initial Dimeglio score (14.9 ± 2.5 [vs 13.5 ± 2.3, p = .042]), its subcomponent of equinus (3.8 ± 0.4 [vs 3.3 ± 0.6, p = .005]), and the number of casts (6.3 ± 2.0 [vs 4.9 ± 1.2, p = .009]) in the 18 patients with difficulties were greater than those of the remaining 29 patients. In addition, the foot length was shorter (7.2 ± 0.6 cm [vs 7.7 ± 0.8 cm, p = .030]) in patients with difficulties. In the regression analysis, both subcomponents of equinus and foot length showed the significance for the occurrence of difficulties. During 8.7 ± 3.8 years, further surgery was needed in 35 patients (74.5%) because of residual or recurrent deformity. The ratio was higher in patients with difficulties (94.4% [vs 62.1%, p = .017]). In our experience, difficulties frequently occurred in feet with rigid equinus and small length, and further surgery was required after the initial correction in almost all of the feet with difficulties.

BGN Mutations in X-Linked Spondyloepimetaphyseal Dysplasia.

Spondyloepimetaphyseal dysplasias (SEMDs) comprise a heterogeneous group of autosomal-dominant and autosomal-recessive disorders. An apparent X-linked recessive (XLR) form of SEMD in a single Italian family was previously reported. We have been able to restudy this family together with a second family from Korea by segregating a severe SEMD in an X-linked pattern. Exome sequencing showed missense mutations in BGN c.439A>G (p.Lys147Glu) in the Korean family and c.776G>T (p.Gly259Val) in the Italian family; the c.439A>G (p.Lys147Glu) mutation was also identified in a further simplex SEMD case from India. Biglycan is an extracellular matrix proteoglycan that can bind transforming growth factor beta (TGF-ß) and thus regulate its free concentration. In 3-dimensional simulation, both altered residues localized to the concave arc of leucine-rich repeat domains of biglycan that interact with TGF-ß. The observation of recurrent BGN mutations in XLR SEMD individuals from different ethnic backgrounds allows us to define "XLR SEMD, BGN type" as a nosologic entity.

The concept of nail matrix onychodermis (onychomatricodermis) in the nail unit: Histology and elastin immunohistochemistry.

BACKGROUNDS: We previously demonstrated the presence of onychodermis below nail matrix and nail bed. Because nail matrix is a producer of nail plate, we hypothesized that onychodermis below nail matrix could be the nail counterpart of follicular dermal papilla. In this study, we sought to further characterize histologic, histochemical, and immunohistochemical features of nail matrix onychodermis. METHODS AND RESULTS: Hematoxylin and eosin slides of 10 polydactyly nail units and 10 nail matrix biopsies from children and adults were reviewed. In polydactyly nail units, the onychodermis beneath nail matrix was characterized by onychofibroblasts showing abundant cytoplasm, and this area was slightly separated from the undersurface of the nail matrix. Nail matrix biopsy specimens also showed similar histology in the nail matrix onychodermis. Alcian blue stain demonstrated mucin deposition in onychofibroblasts within the nail matrix onychodermis. Immunohistochemically, elastin was rarely expressed in the nail matrix onychodermis while it was strongly expressed in the dermis of other areas of polydactyly nail units. Elastin was not expressed in follicular dermal papilla of terminal hair follicles of the scalp. CONCLUSION: Our findings demonstrate the presence and localization of nail matrix onychodermis (onychomatricodermis). Our study also demonstrates similar elastin expression patterns in the onychomatricodermis and follicular dermal papilla.

Clinical and Radiographic Characteristics of Atypical Slipped Capital Femoral Epiphysis.

BACKGROUND: Slipped capital femoral epiphysis (SCFEs) can be idiopathic or atypical (associated with renal failure, radiation therapy, and endocrine disorders). It is important to estimate the likelihood that atypical SCFE shows different clinical and radiographic characteristics and complications with typical SCFEs. METHODS: We retrospectively reviewed 53 patients (66 hips) with SCFEs managed between 1995 and 2016. Sex, age, weight, height, the duration of symptoms the laterality of the slip, and complications were recorded. Bilateral hip and lower extremity long bone radiographs were utilized to record slip angle, genu valgus deformity. Statistical analyses were performed. RESULTS: Among 53 children (32 boys and 21 girls) with 66 SCFEs, 22 children had 29 atypical SCFEs, and 31 children had 38 typical SCFEs. The average age at the time of presentation for the initial SCFEs was 10.9±0.3 years. The average duration of symptoms was 14.1±21.8 weeks. The average Southwick slip angle difference was 23.3±14.8 degrees. There are 43 mild, 13 moderate, and 10 severe SCFEs. 58 were classified as stable, and 8 were unstable. There were significant differences in terms of average age (10.4±2.6 y for atypical SCFEs, 11.2±1.4 for typical SCFEs; P=0.036), average weight (36.2±22.3 kg for patients with atypical slips, compared with 56.9±9.9 kg for those with typical slips; P<0.001), height (132.1±17.6 cm for those with atypical slips, compared with 148.9±12.1 for those with typical slips; P<0.001), and the body mass index (19.4±5.6 kg/cm for those with atypical slips, compared with 25.8±4.6 for those with typical slips; P<0.001). In the group of 22 children with atypical slipped capital epiphysis, there were 19 children with neoplasm (8 neuroblastomas, 3 medulloblastomas, 3 retinoblastomas, 2 ependymomas, 1 craniopharyngioma, 1 Wilms tumor, 1 immature teratoma), 4 children with primary endocrine disorder. We categorized atypical SCFEs in 3 groups by etiology; endocrine disorder-associated (ENDA) SCFEs, chemotherapy-associated (CTA) SCFEs, and radiation therapy-associated (RTA) SCFEs. Subjects of RTA were included if exposed to pelvic irradiation or total body irradiation. There were 4 ENDA, 9 RTA, and 16 CTA. Atypical SCFEs had significantly more valgus slips (P<0.001) and genu valgus deformity (P<0.001) compared with in the group of typical slipped capital epiphysis. Among the group of atypical SCFEs, children with CTA had significantly low body weight, height, and body mass index. CONCLUSIONS: The markedly greater incidence of valgus displacement of proximal femoral epiphysis and genu valgum in childhood cancer survivors with pelvic irradiation and chemotherapy may be associated with atypical SCFE. The authors conclude that in pediatric cancer survivors with hip pain, consideration should be given to atypical SCFE with valgus slip and long-term follow-up of lower extremity alignment. LEVEL OF EVIDENCE: Level III-retrospective comparative study. See instructions for authors for a complete description of levels of evidence.

Complications of distraction osteogenesis in brachymetatarsia: Comparison between the first and fourth brachymetatarsia.

BackgroundRecently, distraction osteogenesis has been widely used to treat brachymetatarsia. However, few papers have compared complications associated with this treatment. The purpose of the present study was to compare the complications between the first and fourth brachymetatarsia treated by distraction osteogenesis. MethodsWe performed distraction osteogenesis to 83 metatarsals in 41 patients between 1999 and 2012. A total of 30 metatarsals received treatment for the first metatarsal (Group A) while 53 metatarsals received treatment with the fourth metatarsal (Group B). ResultsThe complication rate in Group A (40%) was higher than that in Group B (18.9%). Those who had high percentage of lengthening gain were more likely to have complications. A cut-off value for lengthening gain developing complication was 41.3%. ConclusionComplication incidence after distraction osteogenesis was increased when lengthening gain was more than 41.3% for brachymetatarsia. In the 1st metatarsal lengthening, the most common complication was stiffness. In contrast, complications of the 4th metatarsal lengthening were pin-track infection and angular deformity.

CD13 is a marker for onychofibroblasts within nail matrix onychodermis: Comparison of its expression patterns in the nail unit and in the hair follicle.

BACKGROUND: We previously demonstrated the presence of onychodermis, a specialized mesenchymal cell population beneath the nail matrix and proximal nail bed demonstrating CD10 expression. We hypothesize that the onychodermis could be the nail analog of the follicular dermal papilla, which is known to express CD13. We compare CD13 expression patterns between specialized mesenchymes of nail and hair, and compare these findings with CD10 expression patterns. METHODS: CD10 and CD13 immunohistochemistry was performed on polydactyly and adult cadaveric nail units, and on hair follicles in scalp nevus sebaceus excision specimens. RESULTS: CD10 and CD13 were expressed in the mesenchyme below the nail matrix and nail bed. Stronger CD13 expression was observed in the mesenchyme containing onychofibroblasts below the nail matrix compared with that below the nail bed. CD10 was expressed in the dermal sheath of terminal hair follicles, but it was expressed in the dermal sheath and follicular dermal papilla of primitive hair follicles within nevus sebaceus lesions. CD13 was expressed in the dermal sheath and dermal papilla of terminal and primitive hair follicles. CONCLUSION: CD13 may be a marker for onychofibroblasts within nail matrix onychodermis. We demonstrate CD13 expression in the specialized mesenchymes of both nail and hair.

Is sternocleidomastoid muscle release effective in adults with neglected congenital muscular torticollis?

BACKGROUND: Neglected congenital muscular torticollis is rare in adults but may be associated with pain and cosmetic problems. The efficacy of surgical correction in these patients has not been well established in the literature. QUESTIONS/PURPOSES: We sought to describe (1) the primary goals that influenced adults with neglected muscular torticollis to seek surgical correction, (2) improvements of patients' function (specifically ROM) and radiographic parameters associated with deformities, (3) patient-derived outcomes using a previously published scale that includes function, and cosmesis, and (4) complications associated with sternocleidomastoid release in one surgeon's series of patients. METHODS: We retrospectively reviewed the records of all adult patients who had surgical release of the sternocleidomastoid muscle between 2003 and 2011 by one surgeon and who were followed up for more than 1 year after surgery; 42 of these procedures were performed, and complete followup was available for 37 of them (88%). The mean age of the patients was 27 years (range, 18-48 years), and the minimum followup was 1.5 years (mean, 2.4 years; range, 1.5-4.7 years). The primary goal of the operation for each patient was determined to assess if it was met. Functional outcomes were assessed in terms of motion deficit: lateral flexion and rotation. Radiographic outcomes were assessed for cervicomandibular angle, lateral translation of the head and neck, and Cobb's angle of the cervicothoracic spine. The overall clinical results of surgery were assessed with the modified Cheng and Tang scoring system, and complications were tallied from a chart review. RESULTS: The primary goals of surgery were cosmesis in 17 (46%) patients, pain in 11 (30%) patients, and function in nine (24%) patients. Patients for whom pain was the primary goal of surgery were older than the other patients. ROM and radiographic parameters associated with deformity consistently improved in these patients (p < 0.001 in all planes), and the overall results according to the modified Cheng and Tang scoring system indicated that 21 (57%) patients had an excellent result, 12 (32%) had a good result, and four (11%) had a fair result. There were no serious complications and no reoperations in these patients. CONCLUSIONS: Sternocleidomastoid release was beneficial for the treatment of neglected congenital muscular torticollis in adults and was not associated with any serious complications. Surgical treatment led to cosmetic and functional improvements and relieved pain originating from the muscle imbalance brought about by the long-standing deformity. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.

Comparison of orthopaedic manifestations of multiple epiphyseal dysplasia caused by MATN3 versus COMP mutations: a case control study.

BACKGROUND: Multiple epiphyseal dysplasia (MED) is a relatively common skeletal dysplasia mainly involving the epiphyses of the long bones. However, it is a genetically heterogeneous group of diseases sharing certain aspects of the radiologic phenotype. In surveys conducted in East Asia, MATN3 was the most common causative gene, followed by COMP. In this study, the authors compared clinical manifestation of MED patients caused by MATN3 and COMP gene mutations, as well as subsequent orthopaedic interventions. METHODS: Fifty nine molecularly-confirmed MED patients were subjects of this study. The MATN3 gene mutation group comprised of 37 patients (9 female, 28 male). The COMP gene mutation consisted of 22 cases (15 females, 7 males). Medical records and radiographs were reviewed, and questionnaire surveys or telephone interviews were conducted. RESULTS: At the first presentation, the mean age was 8.8 ± 2.8 years (mean ± standard deviation) in the MATN3 group, and 8.5 ± 3.5 years in the COMP group (p = 0.670). The height in the COMP group was significantly shorter than those in the MATN3 group (p < 0.001). Gait abnormality at the first visit (p = 0.041) and the lastest follow-up (p = 0.037) were statistically significant difference. Hip pain (p = 0.084), limitation of daily activity (p = 0.075) at the latest follow-up tended to be more frequent in the COMP group. Hip dysplasia was more common in the COMP group, having significantly larger acetabular angle (p = 0.037), smaller center-edge angle (p = 0.002), severe Stulberg classification (p < 0.001), and smaller femoral head coverage (p < 0.001). CONCLUSIONS: Clinical manifestations of MED caused by MATN3 were milder than manifestations of the COMP mutation group. These differences in clinical manifestation and prognosis justify molecular differentiation between the two genotypes.

High tibial open wedge osteotomy below the tibial tubercle: clinical and radiographic results.

PURPOSE: The purpose of this study was to evaluate the clinical and radiographic results of open wedge HTO below the tubercle for genu varum in relatively young patients. METHODS: Thirty-seven knees in 19 patients with genu varum treated by open wedge HTO below the tubercle between 2001 and 2008 were retrospectively studied. Median follow-up was 36 months (12-108), and median patient age at the time of surgery was 26 years (16-45). Clinical results were evaluated using Lysholm knee scores and Hospital for Special Surgery knee scores. Satisfaction with the results of surgery (0-10 points) was subjectively evaluated using operative scar (1-5 points) and leg shape (1-5 points) results at follow-up. Radiographic evaluations were made using: (1) tibiofemoral angles, (2) mechanical axis deviations, (3) varus-valgus inclinations of the tibial plateau, (4) tibial slopes, and (5) Insall-Savati and (6) Blackburne-Peel ratios. RESULTS: All but one patient achieved radiographic healing and union at the osteotomy site at an average of 3 months postoperatively. Average Lysholm knee score improved from 89.4 ± 8.7 preoperatively to 98.6 ± 2.5 at final follow-up (P = 0.0001), and mean HSS score improved from 91.1 ± 5.6 preoperatively to 98.5 ± 2.0 at final follow-up (P = 0.0001). Mean patient satisfaction score at final follow-up was 8.6 ± 1.0, and mean tibiofemoral angle increased from -1.6° preoperatively to 7.7° at final follow-up (P < 0.0001). The point where the mechanical axis crosses the tibial plateau also shifted significantly from 15.0% preoperatively to 50.6% at final follow-up (P = 0.0002). However, mean posterior tibial slope did not change significantly (9.7° preoperatively and 8.7° at final follow-up; P = NS), and neither did patella heights as measured by Insall-Savati and Blackburne-Peel ratios. CONCLUSION: Both functional assessment and radiographic measures indicated that HTO below the tibial tubercle leads to significant improvements in radiographic parameters and knee function without changes in patellar height or posterior tibial slope. The results obtained support the hypotheses that opening wedge HTO below the tibial tubercle should be recommended in relatively young patients with genu varum. LEVEL OF EVIDENCE: Therapeutic study, Level IV.

Severe equinus deformity after radiofrequency-induced calf muscle reduction.

INTRODUCTION: Radiofrequency-induced calf muscle volume reduction is a commonly used method for cosmetic shaping of the lower leg contour. Functional disabilities associated with the use of the radiofrequency (RF) technique, with this procedure targeting the normal gastrocnemius muscle, still have not been reported. However, the authors have experienced several severe ankle equinus cases after RF-induced calf muscle volume reduction. MATERIAL AND METHOD: This study retrospectively reviewed 19 calves of 12 patients who showed more than 20° of fixed equinus even though they underwent physical therapy for more than 6 months. All were women with a mean age of 32 years (range, 23-41 years). Of the 12 patients, 7 were bilateral. All the patients received surgical Achilles lengthening for deformity correction. To evaluate the clinical outcome, serial ankle dorsiflexion was measured, and the American Orthopedic Foot and Ankle Society (AOFAS) score was evaluated at the latest follow-up visit. The presence of soleus muscle involvement and an ongoing lesion that might affect the postoperative results of preoperative magnetic resonance imaging (MRI) were investigated. Statistical analysis was conducted to analyze preoperative factors strongly associated with patient clinical outcomes. RESULTS: The mean follow-up period after surgery was 18.6 months (range, 12-28 months). At the latest follow-up visit, the mean ankle dorsiflexion was 9° (range, 0-20°), and the mean AOFAS score was 87.7 (range, 80-98). On preoperative MRI, 13 calves showed soleus muscle involvement. Seven calves had ongoing lesions. Five of the ongoing lesions were muscle edema, and the remaining two lesions were cystic mass lesions resulting from muscle necrosis. Ankle dorsiflexion and AOFAS scores at the latest follow-up evaluation were insufficient in the ongoing lesions group. CONCLUSION: Although RF-induced calf muscle reduction is believed to be a safer method than conventional procedures, careful handling is needed because of the side effects that may occur in some instances. The slow progression of fibrosis could be observed after RF-induced calf reduction. Therefore, long-term follow-up evaluation is needed after the procedure. LEVEL OF EVIDENCE IV: Therapeutic case series.

The presence and localization of onychodermis (specialized nail mesenchyme) containing onychofibroblasts in the nail unit: a morphological and immunohistochemical study.

AIMS: Due to its limited availability there has been very little research on the mesenchyme of the nail unit. Recently, we discovered specialized mesenchymal cells beneath the nail matrix and proposed to call them onychofibroblasts. The purpose of this study was to further delineate more precisely by histology and immunohistochemistry the specialized nail mesenchyme. METHODS AND RESULTS: Thirty supernumerary digits were obtained during operations to correct polydactyly. Longitudinal and transverse sections were obtained from formalin-fixed paraffin-embedded blocks. In sections stained with haematoxylin and eosin, a mesenchymal area that showed much more cellularity and less eosinophilic, loose connective tissue was identified beneath the nail matrix and nail bed. Using Alcian blue staining, mucin was detected in this mesenchymal area below the nail matrix and nail bed. Immnunohistochemically, CD10 and versican were expressed strongly in the mesenchyme containing onychofibroblasts under the nail matrix and nail bed. CONCLUSIONS: These results demonstrate the presence and localization of a specialized nail mesenchyme containing onychofibroblasts in a well-defined area beneath the nail matrix and nail bed. Thus, we propose the term onychodermis for this specialized nail mesenchyme that is histologically and immunohistochemically distinct from the dermis of other parts of the nail unit.

Comparative Spatial Transcriptomic and Single-Cell Analyses of Human Nail Units and Hair Follicles Show Transcriptional Similarities between the Onychodermis and Follicular Dermal Papilla.

The nail unit and hair follicle are both hard keratin-producing organs that share various biological features. In this study, we used digital spatial profiling and single-cell RNA sequencing to define a spatially resolved expression profile of the human nail unit and hair follicle. Our approach showed the presence of a nail-specific mesenchymal population called onychofibroblasts within the onychodermis. Onychodermis and follicular dermal papilla both expressed Wnt and bone morphogenetic protein signaling molecules. In addition, nail matrix epithelium and hair matrix showed very similar expressions profile, including the expression of hard keratins and HOXC13, a transcriptional regulator of the hair shaft. Integration of single-cell RNA sequencing and digital spatial profiling data through computational deconvolution methods estimated epithelial and mesenchymal cell abundance in the nail- and hair-specific regions of interest and revealed close transcriptional similarity between these major skin appendages. To analyze the function of bone morphogenetic proteins in nail differentiation, we treated cultured human nail matrix keratinocytes with BMP5, which are highly expressed by onychofibroblasts. We observed increased expressions of hard keratin and its regulator genes such as HOXC13. Collectively, our data suggest that onychodermis is the counterpart of dermal papilla and that BMP5 in onychofibroblasts plays a key role in the differentiation of nail matrix keratinocytes.

Revisit of multiple epiphyseal dysplasia: ethnic difference in genotypes and comparison of radiographic features linked to the COMP and MATN3 genes.

Multiple epiphyseal dysplasia (MED) is a genetically heterogeneous group of diseases characterized by variable degrees of epiphyseal abnormality primarily involving the hip and knee joints. The purpose of this study was to investigate the frequency of mutations in individuals with a clinical and radiographic diagnosis of MED and to test the hypothesis that characteristic radiological findings may be helpful in predicting the gene responsible. The radiographs of 74 Korean patients were evaluated by a panel of skeletal dysplasia experts. Six genes known to be associated with MED (COMP, MATN3, COL9A1, COL9A2, COL9A3, and DTDST) were screened by sequencing. Mutations were found in 55 of the 63 patients (87%). MATN3 mutations were found in 30 patients (55%), followed by COMP mutations in 23 (41%), and COL9A2 and DTDST mutations in one patient (2%) each. Comparisons of radiographic findings in patients with COMP and MATN3 mutations showed that albeit marked abnormalities in hip and knee joints were observed in both groups, the degree of involvement and the morphology of dysplastic epiphyses differed markedly. The contour of the pelvic acetabulum, the presence of metaphyseal vertical striations, and/or the brachydactyly of the hand were also found to be highly correlated with the genotypes. The study confirms that MATN3 and COMP are the genes most frequently responsible for MED and that subtle radiographic signs may give precious indications on which gene(s) should be prioritized for mutational screening in a given individual.

Surgical Outcomes and Predictive Factors of Medial Toe Excision for Polysyndactyly of the Fifth Toe.

BACKGROUND: We aimed to report surgical outcomes and analyze prognostic factors of medial toe excision for polysyndactyly of the fifth toe. METHODS: We reviewed the details of 139 consecutive patients who underwent surgery for postaxial polydactyly of the foot from 2009 to 2018. Among these, 83 patients (90 feet) with polysyndactyly of the fifth toe, treated by medial toe excision (between the duplicated toes) and reconstruction of the fourth web space using a dorsal rectangular flap, were included. The toe alignment and stability were restored by chondroplasty and soft tissue balancing without an osteotomy. A full-thickness skin graft was performed in 52 feet. The mean age at surgery was 27.1 ± 17.5 months and the mean duration of follow-up was 42.8 ± 24.9 months. RESULTS: At the last follow-up, a relatively small size of the reconstructed toe was observed in 19 feet (19/90, 21.1%). Proximal duplication level (metatarsal or proximal phalanx type) and preoperative hypoplasia of the remaining toe were related to the small postoperative size. Valgus deformity of the remaining toe was observed in 2 feet (2/90, 2.2%). We observed 17 cases with delayed healing or early postoperative wound infection. Among these, 7 cases (7/90, 7.8%) showed postoperative thickening or advancement of the web, which was not observed in cases without wound problems. No cases had functional disturbance or pain. CONCLUSION: The overall surgical outcomes were satisfactory without an osteotomy. Patients with a proximal duplication level or preoperative hypoplasia of the remaining toe should be informed of its possible small size postoperatively. LEVELS OF EVIDENCE: Level IV, retrospective case series.

Characterization of the Onychomatricodermis Containing Onychofibroblasts of the Nail Unit : Histology, Immunohistochemistry, and Electron Microscopic Study.

BACKGROUND: We recently discovered the presence of specialized nail mesenchyme below the nail matrix and designated it as onychomatricodermis. OBJECTIVE: We did further research to characterize the histologic, histochemical, immunohistochemical and ultrastructural features of the onychomatricodermis containing onychofibroblasts in the nail unit. METHODS: Ten polydactyly nail unit specimens and 8 nail matrix biopsies were included. H&E-stained slides were reviewed. We did Alcian blue staining and Masson Trichrome staining, as well as immunohistochemical staining for type I collagen, CD10, CD13 and CD34. In addition, polydactyly nail units were examined by transmission electron microscopy. RESULTS: In H&E staining, the specialized mesenchyme called onychomatricodermis was observed to be slightly distant from the undersurface of the nail matrix and be less eosinophilic area. Onychomatricodermal onychofibroblasts showed light purple abundant cytoplasm. Masson Trichrome staining revealed fewer collagen fibers within the onychomatricodermis. In Alcian blue staining the onychomatricodermis showed mucin deposition within the onychofibroblasts and around them. Immunohistochemically, type I collagen was expressed much less in the onychomatricodermis while it was strongly expressed elsewhere in the nail unit. In nail matrix biopsy specimens onychomatricodermal onychofibroblasts expressed CD10 and CD13 strongly, and expressed CD34 as well. Ultrastructurally, collagen fibrils were found sparsely within the onychomatricodermis, whereas collagen fibrils were densely distributed in the dermis of other parts of the nail unit. CONCLUSION: We demonstrated that there was less collagen expression in the onychomatricodermis containing onychofibroblasts. In addition, we found morphological and immunohistochemical features of onychomatricodermal onychofibroblasts (onychofibroblasts of Dongyoun). These findings support the presence of onychomatricodermis containing onychofibroblasts in the nail unit.

Single-cell RNA sequencing of human nail unit defines RSPO4 onychofibroblasts and SPINK6 nail epithelium.

Research on human nail tissue has been limited by the restricted access to fresh specimen. Here, we studied transcriptome profiles of human nail units using polydactyly specimens. Single-cell RNAseq with 11,541 cells from 4 extra digits revealed nail-specific mesenchymal and epithelial cell populations, characterized by RSPO4 (major gene in congenital anonychia) and SPINK6, respectively. In situ RNA hybridization demonstrated the localization of RSPO4, MSX1 and WIF1 in onychofibroblasts suggesting the activation of WNT signaling. BMP-5 was also expressed in onychofibroblasts implicating the contribution of BMP signaling. SPINK6 expression distinguished the nail-specific keratinocytes from epidermal keratinocytes. RSPO4+ onychofibroblasts were distributed at close proximity with LGR6+ nail matrix, leading to WNT/ß-catenin activation. In addition, we demonstrated RSPO4 was overexpressed in the fibroblasts of onychomatricoma and LGR6 was highly expressed at the basal layer of the overlying epithelial component, suggesting that onychofibroblasts may play an important role in the pathogenesis of onychomatricoma.