Injury mechanism affects the stability of suture-button syndesmosis fixation.

BACKGROUND: Ankle syndesmosis injury is a common condition, and the injury mechanism can be sorted into pure syndesmosis injury, Weber-B, and Weber-C type fractures. This study aims to evaluate the treatment outcomes and stability of suture-button fixation for syndesmosis injury with different injury mechanisms. We hypothesized that injury mechanisms would alter the stability of suture-button fixation. METHODS: We retrospectively reviewed 63 patients with ankle syndesmosis injury who underwent surgery with TightRope (Arthrex, Naples, FL, USA) from April 2014 to February 2019. The stability of suture-button fixation with TightRope was evaluated by comparing the preoperative, postoperative, and final follow-up measurements of tibiofibular clear space (TFCS), tibiofibular overlap (TFO), and medial clear space (MCS). A subgroup analysis for each demographic group and injury type including pure syndesmosis injury, Weber-B, and Weber-C type fractures were performed. RESULTS: Syndesmosis was effectively reduced using TightRope. After the index surgery, the tibiofibular clear space was reduced from 7.73 to 4.04 mm, the tibiofibular overlap was increased from 3.05 to 6.44 mm, and the medial clear space was reduced from 8.12 to 3.54 mm. However, syndesmosis widening was noted at the final follow-up, especially in Weber-C type fractures (TFCS 3.82 to 4.45 mm, p < 0.01 and TFO 6.86 to 6.29 mm, p = 0.04). Though widened, the final follow-up values of tibiofibular clear space and tibiofibular overlap were in the acceptable range. Postoperatively and at the final follow-up, medial clear space was found to be significantly larger in the Weber-C group than in the pure syndesmosis and Weber-B groups (p < 0.05). CONCLUSIONS: Suture-button fixation can offer anatomic reduction and dynamic fixation in syndesmosis injuries. However, when using this modality for Weber-C type fractures, more attention should be focused on the accuracy of reduction, especially of medial clear space, and rediastasis should be carefully monitored. TRIAL REGISTRATION: This trial was retrospectively approved by TMU-JIRB. Registration number N202004122, and the date of approval was May 06, 2020. LEVEL OF EVIDENCE: III.

Hypoxia enhances chondrogenesis and prevents terminal differentiation through PI3K/Akt/FoxO dependent anti-apoptotic effect.

Hypoxia, a common environmental condition, influences cell signals and functions. Here, we compared the effects of hypoxia (1% oxygen) and normoxia (air) on chondrogenic differentiation of human mesenchymal stem cells (MSCs). For in vitro chondrogenic differentiation, MSCs were concentrated to form pellets and subjected to conditions appropriate for chondrogenic differentiation under normoxia and hypoxia, followed by the analysis for the expression of genes and proteins of chondrogenesis and endochondral ossification. MSCs induced for differentiation under hypoxia increased in chondrogenesis, but decreased in endochondral ossification compared to those under normoxia. MSCs induced for differentiation were more resistant to apoptosis under hypoxia compared to those under normoxia. The hypoxia-dependent protection of MSCs from chondrogenesis-induced apoptosis correlated with an increase in the activation of the phosphatidylinositol 3-kinase (PI3K)/Akt/FoxO pathway. These results suggest that the PI3K/Akt/FoxO survival pathway activated by hypoxia in MSCs enhances chondrogenesis and plays an important role in preventing endochondral ossification.

Isolation of mesenchymal stem cells from human ligamentum flavum: implicating etiology of ligamentum flavum hypertrophy.

STUDY DESIGN: To demonstrate the existence of mesenchymal stem cells (MSCs) in ligamentum flavum (LF) and their pathogenic role in LF hypertrophy. OBJECTIVE: To isolate and characterize LF-derived MSCs and their response to transforming growth factor-beta 1 (TGF-ß1) and trichostatin A (TSA), a histone deacetylase inhibitor (HDACi). SUMMARY OF BACKGROUND DATA: LF is a connective tissue, of which hypertrophic changes induce spinal stenosis. The pathogenic role of TGF-ß1 in spinal stenosis has been implicated. TSA has been shown to suppress TGF-ß1-induced alpha-smooth muscle actin (α-SMA), type I and III collagen synthesis in a variety of cells. MSCs have been isolated from a variety of adult tissues, except LF. Whether MSCs exist in LF and their response to TGF-ß1 and TSA is not clear. METHODS: The MSCs from LF were isolated and cultured. Their phenotypic character, linage differentiation potential, and response to TGF-ß1 and TSA were analyzed. RESULTS: LF-derived MSCs have the similar profile of surface markers as bone marrow MSCs. They were demonstrated to have the potential to be differentiated into osteoblasts, adipocytes, and chondrocytes. Administration of TGF-ß1 stimulated cell proliferation, enhanced the gene expression of type I and III collagen, and increased the gene expression and protein level of α-SMA. TSA blocked the fibrogenic effects of TGF-ß1. CONCLUSION: The current results demonstrated the isolation of MSCs from LF. The cellular response to TGF-ß1 implied that these cells might play an important role in the pathogenesis of LF hypertrophy. TSA, which blocks the effects of TGF-ß1, may be a potent therapeutic choice for inhibiting LF hypertrophy.

Trichostatin A inhibits TGF-ß1 induced in vitro chondrogenesis of hMSCs through Sp1 suppression.

Trichostatin A (TSA) is a histone deacetylase inhibitor (HDACi) known to modulate differentiation of many cells. However, its effect on chondrogenesis remains elusive. This study was aimed to investigate the effects of TSA on in vitro transforming growth factor-ß1 (TGF-ß1)-induced chondrogenesis of human mesenchymal stem cells (hMSCs). The pellet cultures of hMSCs in a chondrogenic medium were exposed to TGF-ß1 and TSA. Quantitative reverse transcription/polymerase chain reaction (PCR) analysis, Alcian blue staining, and immunohistochemistry staining were used to confirm and compare the differences in chondrogenesis by analyzing the mRNA of chondrogenic genes (Sox9, Aggrecan, and Col2A1), synthesis of chondrogenic proteins and type II collagen, respectively. TGF-ß1 signaling and its downstream targets were determined by western blot analysis. TGF-ß1 led to significant increases in chondrogenic gene expression and the synthesis of chondrogenic proteins. However, TSA significantly decreased chondrogenic gene expression and the synthesis of chondrogenic proteins in a dose-dependent manner. TGF-ß1 increased phosphorylation of Smad 2/3 and Sp1 expression around half an hour after induction. The increase of Sp1, but not Smad 2/3 activation was almost completely blocked by the addition of TSA. The chondrogenic effect of TGF-ß1 was also suppressed by the Sp1-binding inhibitor mithramycin A. Finally, overexpression of Sp1 abolished TSA-mediated inhibition of TGF-ß1-induced chondrogenesis. Our study showed that TSA inhibited chondrogenesis through inhibition of TGF-ß1-induced Sp1 expression. Furthermore, Sp1 could be a useful tool in future studies looking into biological mechanisms by which chondrogenesis of hMSCs can be augmented, especially in the area of clinical application.

Open reconstruction of large bony glenoid erosion with allogeneic bone graft for recurrent anterior shoulder dislocation.

BACKGROUND: Severe glenoid bone loss in recurrent anterior glenohumeral instability is rare and difficult to treat. PURPOSE: The authors present a surgical technique using allogeneic bone grafting for open anatomic glenoid reconstruction in addition to the capsular shift procedure. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Nine consecutive patients with a history of recurrent anterior shoulder instability underwent reconstruction of large bony glenoid erosion with a femoral head allograft combined with an anteroinferior capsular shift procedure. Preoperative computed tomographic and arthroscopic evaluation was performed to confirm a > or =120 degrees osseous defect of the anteroinferior quadrant of the glenoid cavity, which had an "inverted-pear" appearance. Patients were followed for at least 4.5 years (range, 4.5-14). Serial postoperative radiographs were evaluated. Functional outcomes were assessed using Rowe scores. RESULTS: All grafts showed bony union within 6 months after surgery. The mean Rowe score improved to 84 from a preoperative score of 24. The mean loss of external rotation was 7 degrees compared with the normal shoulder. One subluxation and 1 dislocation occurred after grand mal seizures during follow-up. These 2 patients regained shoulder stability after closed reduction. The remaining patients did not report recurrent instability. All patients resumed daily activities without restricted motion. CONCLUSION: This technique for open reconstruction is viable for the treatment of recurrent anterior glenohumeral instability with large bony glenoid erosion.

Disassembly and dislocation of a bipolar hip prosthesis.

Dislocation of a hip prosthesis is a common complication. In usual cases of hip prosthesis dislocation, the prosthetic femoral head comes out from either the natural acetabular cavity in a bipolar hemiarthroplasty or the prosthetic acetabulum in a total hip arthroplasty. Only a few cases of bipolar hip prosthesis dislocation due to dissociation between the polyethylene and inner head of the prosthesis have been reported. We describe a rare case of disassembly of the inner head from the bipolar outer prosthesis in an osteoarthritic acetabulum. A 72-year-old woman had undergone bipolar hemiarthroplasty due to fracture of the left femoral neck about 10 years previously. Recently, she sustained an injury after falling from a chair, and examinations revealed an unusual disassembly-dislocation of the bipolar hip prosthesis. We classified this failure in our patient as a type II failure, representing extreme varus position of the outer head in the acetabulum, dislocation of the inner head from the outer head, and a detached locking ring around the stem neck. This mechanism of failure as shown in our patient rarely occurs in the bipolar prosthesis of the self-centering system. Osteoarthritic change of the acetabulum would place the outer head in the varus position, increasing wear on the beveled rim by impinging the femoral stem neck and causing dislodgment of the inner locking ring and consequent disassembly-dislocation of the inner head.

Tenosynovial lipoma arborescens of the ankle in a child.

Lipoma arborescens is a rare entity of the synovium and frequently occurs in the joints. Lipoma arborescens involving the synovial sheaths of the tendons is exceedingly rare. We report a case of a 12-year-old girl with lipoma arborescence affecting the synovial sheaths of the peroneal, posterior tibialis, and flexor tendons. Identification of the typical features of fat tissues in the proliferative synovium on MRI may help in making a correct diagnosis. The clinical presentation and MRI findings are described, and the entity is briefly reviewed.

Operative treatment of displaced medial epicondyle fractures in children and adolescents.

Twenty-five patients who sustained displaced medial epicondyle fractures were treated by various surgical techniques. There were 18 males and 7 females. The mean age was 13.7 years. Surgical outcome was evaluated by use of the Elbow Assessment Score of the Japanese Orthopedic Association. Many variables that might influence the surgical outcome were considered. The results revealed no significant correlation between surgical outcome and injury mechanism, displacement, interval from injury to surgery, dislocation, fixation method, or duration of immobilization. The motion arc was moderately decreased in 1 patient treated by use of screw fixation. Moderate instability to valgus stress was noted in another patient treated by use of pin fixation (K-wires). The treatment results were all scored, and the patients with medial epicondylar fractures (displacement >5 mm) showed good to excellent results with operative treatment. Residual deformity did not compromise cosmetic appearance or clinical results. Therefore, operative treatment is a suitable choice for managing these fractures in children and adolescents.