Acquired adult flatfoot is a deformity characterized by a decreased medial longitudinal arch and a hindfoot valgus with or without forefoot abduction. The etiologies of this deformity include posterior tibial tendon dysfunction, rheumatoid arthritis, trauma, Charcot's joint, neurologic deficit, and damage to the medial spring ligament complex or plantar fascia. Among these, posterior tibial tendon dysfunction is the most well-known cause. Although posterior tibial tendon dysfunction has been regarded as a synonym of acquired adult acquired flatfoot, failure of the ligaments supporting the arch can also result in progressive deformity even without a posterior tibial tendon problem. The authors describe the pathophysiology, diagnosis, and nonoperative treatment of acquired adult flatfoot, focusing on posterior tibial tendon dysfunction.

Acquired adult flatfoot deformity is characterized by flattening of the medial longitudinal arch and dysfunction of the posteromedial soft tissues, including the posterior tibial tendon. When the non-operative treatment fails to result in improvement of symptoms, surgery should be considered. Operative techniques include flexor digitorum longus tendon transfer, calcaneal medial slide osteotomy, lateral column lengthening, and arthrodesis of the hindfoot. The principle of correcting the deformity while avoiding overcorrection and excessive stiffness is important in achievement of good outcomes in these patients.

Purpose: The purpose of this study is to evaluate the efficacy of mesenchymal stem cell (MSC) isolation by the magnetic-activated cell sorting (MACS) method in tendon tissue-derived cells compared to the colony picking method for isolation of MSCs by picking colony-forming cells. Materials and Methods: Human tendon-derived cells were isolated by enzyme digestion using normal tendon tissues from three donors. We used the magnetic kit and well-known MSC markers (CD90 or CD105) to isolate MSCs in tendon-derived cells using MACS. Cloning cylinders were used to isolate colony-forming cells having MSC characteristics in tendon-derived cells. Colony-forming unit-fibroblast (CFU-F) assay was used to evaluate the self-renewal capacity of cells isolated using the colony picking method or MACS. For comparison of differentiation potentials into osteogenic or adipogenic lineage between two groups, alizarin red S and oil red O staining were performed at 14 days after induction of differentiation in vitro. Results: Flow cytometry results showed that early passage tendon-derived cells expressed CD44 in 99.13%, CD90 in 56.51%, and CD105 in 86.19%. In the CFU-F assay, CD90+ or CD105+ cells isolated with MACS showed larger colony formation in size than cells isolated using the colony picking method. We also observed that CD90+ or CD105+ cells were constantly differentiated into both osteogenic and adipogenic lineages in cells from all donors, whereas cells isolated using the colony picking method were heterogeneous in differentiation potentials to the osteogenic and adipogenic lineages. Conclusion: CD90+ or CD105+ cells isolated using MACS showed superior MSC characteristics in the self-renewal and multi-differentiation capacities compared with cells isolated using the colony picking method.

Purpose: Ligament reattachment technique using a suture anchor appears to show satisfactory functional outcomes and mechanical stability compared with conventional bone tunnel technique. This study was prospectively conducted in order to evaluate functional outcomes of modified Brostrom procedures using the suture bridge technique for chronic ankle instability in athletes. Materials and Methods: Twenty eight athletes under 30 years of age were followed for more than two years after undergoing the modified Brostrom procedure using the suture bridge technique. Functional evaluation consisted of the foot and ankle outcome score (FAOS), foot and ankle ability measure (FAAM) score. Range of motion and time to return to exercise were evaluated using a periodic questionnaire. Talar tilt angle and anterior talar translation were measured through stress radiographs for evaluation of mechanical stability. Results: FAOS improved significantly from preoperative mean 59.4 points to 91.4 points (p<0.001). Daily living and sport activity scores of FAAM improved significantly from preoperative mean 50.5, 32.5 points to 94.8, 87.3 points, respectively (p<0.001). Talar tilt angle and anterior talar translation improved significantly from preoperative mean $16.8^{\circ}$, 13.5 mm to $4.2^{\circ}$, 4.1 mm at final follow-up (p<0.001). Times to return to exercise were as follows: mean 10.2 weeks in jogging, 15.4 weeks in spurt running, 13.1 weeks in jumping, 11.5 weeks in walking on uneven ground, 9.1 weeks in standing on one leg, 7.2 weeks in tip-toeing gait, 8.4 weeks in squatting, and 10.6 weeks in descending stairs. Conclusion: Modified Brostrom procedure using the suture bridge technique showed satisfactory functional outcomes for chronic ankle instability in athletes. Optimal indication and cost-effectiveness of the suture bridge technique will be studied in the future.

Purpose: The purpose of this study is to report on the result of repairing Achilles tendon using absorbable suture under nerve block. Materials and Methods: We retrospectively reviewed 20 patients with acute Achilles tendon rupture who were followed up for at least six months after the operation. We repaired Achilles tendon using two absorbable sutures using the Krackow technique for the proximal stump and the Kessler technique for the distal stump. A programmed postoperative management including non-weight bearing with a short leg cast for four weeks after the operation was applied for all patients. We evaluated clinical results using American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, visual analogue scale (VAS) for satisfaction, range of motion of ankle, functional recovery rate, and the starting time of single heel raise. Results: The mean VAS score for satisfaction and AOFAS score was 9.2 and 93.0, respectively. The affected ankle showed a mean dorsiflexion rate of 90% and plantar-flexion rate of 94% compared to the uninjured side. The single heel raise could start at a mean of 3.5 months after the operation. Conclusion: Treatment of Achilles tendon rupture with absorbable suture material using the hybrid suture technique of proximal Krackow and distal Kessler showed sufficient stability and minimal chronic inflammatory reaction.

Purpose: This study was designed to evaluate the clinical efficacy of temporary K-wire fixation in F-plate fixation for displaced intra-articular calcaneal fractures. Materials and Methods: Two groups (group 1 with F-plate fixation only and group 2 with temporary K-wire fixation and F-plate fixation) of patients were included in this study. The temporary K-wire was removed six weeks after the operation. Each group consisted of 33 cases. Rotational axis angles were measured radiographically and the foot and ankle outcome score (FAOS) was used for clinical assessment. Results: In group 1, the mean rotational axis angle was reduced from $27^{\circ}$ preoperatively to $5.59^{\circ}$ postoperatively and the angle at last follow-up was $9.94^{\circ}$. There was an increase in angle of $4.35^{\circ}$ between postoperative and the last follow-up measurement. In group 2, the mean rotational axis angle was reduced from $21.2^{\circ}$ preoperatively to $4.39^{\circ}$ postoperatively and the angle at last follow-up was $5.91^{\circ}$. There was an increase in angle of $1.52^{\circ}$ between postoperative and the last follow-up measurement. Significant difference in the changes of rotational axis angle was observed between the two groups. However, no significant difference in FAOS was observed between the two groups. Conclusion: Temporary K-wire fixation can prevent reduction loss when treating displaced intra-articular calcaneal fractures with an F-plate.

Purpose: The purpose of this study was to assess the treatment outcomes and prognosis of Lisfranc joint fracture and dislocation according to the mechanism of injury and treatment method. Materials and Methods: Twenty six patients with Lisfranc fracture-dislocation who had been treated surgically were included in this retrospective study. The patients were divided into two groups according to mechanism of injury: direct crushing injury (16 patients) and indirect rotational or compressive injury (10 patients). The patients were also divided into three groups according to the surgical methods. The parameters used were radiographic evaluation, patients' subjective satisfaction levels, length of hospital stay, and the American Orthopaedic Foot and Ankle Society (AOFAS) midfoot score. Statistical analysis was performed. Results: The mean postoperative AOFAS midfoot score was 78.7. The mean length of stay was 39.6 days. Statistically significant differences in subjective satisfaction, AOFAS midfoot score, and length of hospital stay were observed between the two groups (p<0.05). However, no significance differences were observed between the three groups who were divided according to the different surgical methods (p>0.05). Conclusion: Mechanism of trauma and the severity of soft-tissue injury were significant prognostic factors affecting the surgical outcomes of Lisfranc joint fracture and dislocation.

Intravascular papillary endothelial hyperplasia (IPEH) has appeared in the literature under a variety of names, including Masson's tumor, Masson's hemangioma, and Masson's pseudoangiosarcoma. It is a benign lesion of the skin and subcutaneous tissue characterized by reactive proliferation of vascular endothelial cells with papillary formations. The clinical picture is not specific and the lesion resembles malignant angiosarcoma clinically and histopathologically. Therefore, it is often mistaken for angiosarcoma and a group of other benign and malignant vascular lesions. We report on a case of IPEH adherent to peripheral nerve treated with operative excision.

Skin grafting is often required for diabetic ulcerative foot lesions. In skin grafting, effective regional or local anesthesia into the donor and recipient areas plays a significant role in continuous control of pain. We report on a technique of ultrasound-guided nerve block on the femoral, sciatic, and lateral femoral cutaneous nerves in large split-thickness skin grafting for ulcer of the foot and leg.