Tranexamic Acid Can Reduce Early Tendon Adhesions After Rotator Cuff Repair and Is Not Detrimental to Tendon-Bone Healing: A Comparative Animal Model Study.

PURPOSE: To determine the effects of topical tranexamic acid (TXA) administration on tendon adhesions, shoulder range of motion (ROM), and tendon healing in an acute rotator cuff repair rat model. METHODS: A total of 20 Sprague Dawley rats were used. Tendon adhesion, ROM, and biomechanical and histological analysis of tendon-bone healing was conducted at 3 and 6 weeks after surgery. The rats underwent rotator cuff repair surgery on both shoulders and were administered TXA via subacromial injections. The tendon adhesion was evaluated macroscopically and histologically. Biomechanical tendon healing was measured using a universal testing machine, and histological analysis was quantified by H&E, Masson's trichrome, and picrosirius red staining. RESULTS: At 3 weeks after surgery, the adhesion score was significantly lower in the TXA group (2.10 ± 0.32) than in the control group (2.70 ± 0.48) (P = .005), but there was no significant difference between the 2 groups at 6 weeks. Regarding ROM, compared with the control group, the TXA group showed significantly higher external rotation (36.35° ± 4.52° vs 28.42° ± 4.66°, P < .001) and internal rotation (45.35° ± 9.36° vs 38.94° ± 5.23°, P = .013) 3 weeks after surgery. However, at 6 weeks, there were no significant differences in external and internal rotation between the 2 groups. In the biomechanical analysis, no significant differences in gross examination (3 weeks, P = .175, 6 weeks, P = .295), load to failure (3 weeks, P = .117, 6 weeks, P = .295), or ultimate stress (3 weeks, P = .602, 6 weeks, P = .917) were noted between the 2 groups 3 and 6 weeks after surgery. In the histological analysis of tendon healing, no significant differences in the total score (3 weeks, P = .323, 6 weeks, P = .572) were found between the 2 groups 3 and 6 weeks after surgery. CONCLUSIONS: Topical TXA administration showed a beneficial effect in reducing tendon adhesions and improving ROM 3 weeks postoperatively and had no effect at 6 weeks. This suggests that additional intervention with TXA may be useful in achieving long-term improvement in shoulder stiffness. Additionally, TXA may increase tissue ground substance accumulation in the late postoperative period but does not adversely affect tendon-bone interface healing. CLINICAL RELEVANCE: The use of TXA after rotator cuff repair has no effect on tendon-bone interface healing in clinical practice and can improve shoulder stiffness in the early postoperative period. Additional research on the long-term effects is needed.

Is ulnar shortening osteotomy effective for the treatment of ulnar styloid impaction syndrome compared to ulnar impaction syndrome?

PURPOSE: This study aimed at evaluating the outcomes of ulnar shortening osteotomy (USO) for the treatment of ulnar styloid impaction syndrome (USIS) and to compare them with those of USO for the treatment of ulnar impaction syndrome (UIS). METHODS: We enrolled 144 patients who underwent USO between March 2015 and October 2021. The patients were divided into a UIS group (group I, n = 93) and a USIS group (group II, n = 51). Clinical and radiological parameters, including Disabilities of the Arm, Shoulder, and Hand (DASH) score, ulnar variance, ulnar styloid length, and ulnar styloid process index (USPI), were collected pre-operatively and one year post-operatively, and a comparative analysis was performed. RESULTS: The DASH score showed significant improvement in both groups (p < .001 and p < .001), and there was no significant difference between the two groups one year after surgery (p = .143). The USPI was significantly different between the two groups (p < .001). The ulno-lunate and ulno-triquetrum distances showed significant increases in both groups, with significant differences between the two groups (p = .020, and p < .001, respectively). The incidence of post-operative arthritic changes in the distal radioulnar joint was significantly greater in the UIS group than that in the USIS group (21 vs 3, respectively; p = .017). No remarkable differences were observed in the post-operative evidence of chondromalacia at the last follow-up between the two groups. CONCLUSION: The USO, which was performed as a treatment for USIS showed reliable outcomes compared to the USO for the treatment of UIS. Therefore, USO is a viable option for the treatment of USIS.

Editorial Commentary: Overtensioning of Rotator Cuff Rear Repair Predisposes to Failure of Complete Healing.

Overtension repair of rotator cuff tear may predispose to the failure of postoperative integrity of the rotator cuff tendon. Surgeons should consider the size of the rotator cuff tear and maintain adequate tension for successful rotator cuff repair. Feel the tension on the tendon: too much can poison the outcome.

How Much Will High Tension Adversely Affect Rotator Cuff Repair Integrity?

PURPOSE: To suggest a cutoff value of tension related to retear of a repaired chronically contracted rotator cuff and to analyze the correlation between predictive factors and integrity of repair in large to massive contracted rotator cuff tears (RCTs). METHODS: We analyzed arthroscopic rotator cuff repairs for large to massive (>3 cm) contracted RCTs, not amenable to complete repair by standard means with meticulous release, with a minimum of 1 year follow-up. An intraoperative procedure was designed for the estimation of repair tension using a tensiometer. Clinical and radiological findings were compared between the healed group and the retear group, and magnetic resonance imaging was performed ∼1 year postoperatively for the evaluation of integrity of the repair site. The receiver operating characteristic curve was used to identify the cutoff value of the independent factors. Factors affecting postoperative retear were examined with multivariate analysis. RESULTS: Fifty patients were enrolled in this study and divided into the healed group (31 patients) and the retear group (19 patients) according to the follow-up magnetic resonance imaging findings. Significant results showed that tension (5.13 < 95% confidence interval [CI] < 58.15, P < .001) and acromiohumeral interval (AHI) (1.13 < 95% CI < 33.10, P = .013) were important factors for the integrity of rotator cuff repair. The cutoff value of tension was 35 N, and an AHI <6.6 mm may also be considered a predictor of retear. An occupation ratio of the tension >35 N was the strongest predictor of retear, with an area under the curve of 0.799, sensitivity of 84.2%, and specificity of 67.7% (accuracy = 76.0%). CONCLUSIONS: The integrity of a large to massive rotator cuff repair is strongly related to the tension to reach the articular margin of the footprint and AHI. We found that the possibility of retear increases when tension ≥35 N is required. AHI <6.6 mm may also be considered a predictor of retear. LEVEL OF EVIDENCE: Level III, retrospective cohort design.

Implantation of Culture-Expanded Bone Marrow Derived Mesenchymal Stromal Cells for Treatment of Osteonecrosis of the Femoral Head.

BACKGROUND: Although core decompression (CD) with stem cell for the treatment of osteonecrosis of the femoral head (ONFH) showed promising results in many reports, the efficacy remains uncertain. We aimed to evaluate the efficacy of CD with culture-expanded autologous bone marrow-derived mesenchymal stem cell (BM-MSC) implantation in early stage ONFH. METHODS: A total of 18 patients (22 hips) with ONFH who underwent CD with culture-expanded BM-MSC implantation from September 2013 to July 2020 were retrospectively reviewed. The median age was 35.0 years [interquartile range (IQR), 28.5-42.0], and the median follow-up period was 4.0 years (IQR, 2.0-5.3). The median number of MSCs was 1.06 × 108. To evaluate radiographic and clinical outcomes, Association Research Circulation Osseous (ARCO) classifications, Japanese Investigation Committee classification, combined necrotic angle (CNA) visual analogue scale (VAS) and Harris Hip Score (HHS) were checked at each follow-up. RESULTS: The preoperative stage of ONFH was ARCO 2 in 14 hips and ARCO 3a in 8 hips. The ARCO staging was maintained in 7 hips in ARCO 2 and 4 hips in ARCO 3a. The radiographic failure rate of ARCO 2 and 3a was 14.3 and 50%, respectively. Furthermore, CNA decreased to more than 20° in 6 hips (four were ARCO 2 and two were ARCO 3a).There was no significant difference in the VAS and HHS (P = 0.052 and P = 0.535, respectively). Total hip arthroplasty was performed in 4 hips. CONCLUSION: CD with culture-expanded autologous BM-MSCs showed promising results for the treatment of early stage ONFH.

Effect of Gabapentin on Tendon-to-Bone Healing in a Rat Model of Rotator Cuff Repair.

BACKGROUND: Gabapentin is often used as an analgesic after rotator cuff repair surgery and is recommended as an additional analgesic for arthroscopic rotator cuff repairs. However, evidence of its effects on biological healing mechanisms is lacking. The objective of this study was to investigate the potential of gabapentin in improving tendon-to-bone healing after rotator cuff repair using a rat model. MATERIALS AND METHODS: A total of 20 male rats were randomly allocated to one of two groups: group 1 (repair only, n=10) or group 2 (gabapentin injection, n=10). The rats in the experimental group (group 2) were administered 80 mg/kg of gabapentin subcutaneously 30 minutes before surgery, followed by 80 mg/kg subcutaneously every 24 hours for 48 hours. We used the left shoulder of every rat, while for biomechanical analysis, we used the right shoulder. RESULTS: There was no significant difference in the load to failure, ultimate stress, or elongation between the groups. Collagen continuity, orientation, and density were better in group 2 than group 1. CONCLUSION: In a rat model of rotator cuff repair, gabapentin had a positive impact on the quality of collagen organization at the junction between the tendon and bone, while preserving the biomechanical properties. We propose the use of gabapentin as a supplementary analgesic agent for postoperative pain relief after arthroscopic rotator cuff repair; however, further studies of the effect of gabapentin on biological healing mechanisms are required. [Orthopedics. 202x;4x(x):xx-xx.].

Biomechanical and histological evaluation of aspirin in rotator cuff tear rat model.

Background: Aspirin is a representative non-steroidal anti-inflammatory drug (NSAIDs) and has been commonly used for the treatment of tendinopathy in clinical practice. In this study, we aimed to evaluate the biomechanical and histological healing effects of aspirin on the healing of the tendon-to-bone interface after rotator cuff tear repair. Methods: A total of 20 male Sprague-Dawley rats were randomly divided into two groups of 10 rats each. Group-C performed repaironly, and group-aspirin treated with aspirin after tendon repair. Group-aspirin rat were intraperitoneally injected with aspirin at 10 mg/kg every 24 h for 7 days. Eight weeks after surgery, the left shoulder of each rat was used for histological analysis and the right shoulder for biomechanical analysis. Results: In the biomechanical analysis, there was no significant difference in load-to-failure (group-C: 0.61 ± 0.32 N, group-aspirin: 0.74 ± 0.91 N; p = .697) and ultimate stress (group-C: 0.05 ± 0.01 MPa, group-aspirin: 0.29 ± 0.43 MPa; p = .095). For the elongation (group-C: 222.62 ± 57.98%, group-aspirin: 194.75 ± 75.16%; p = .028), group-aspirin confirmed a lower elongation level than group-C. In the histological evaluation, the Bonar score confirmed significant differences in collagen fiber density (group-C: 1.60 ± 0.52, group-aspirin: 2.60 ± 0.52, p = .001) and vascularity (group-C: 1.00 ± 0.47, group-aspirin: 2.20 ± 0.63, p = .001) between the groups. Conclusions: Aspirin injection after rotator cuff tear repair may enhance the healing effect during the early remodeling phase of tendon healing.

Be aware of the "O" sign in the bipolar cup dissociation during closed reduction of bipolar dislocation: A case report.

RATIONALE: Bipolar cup dissociation following hip hemiarthroplasty is a rare complication of which only a few cases have been reported, and it usually requires revision surgery because of difficulties in closed reduction. PATIENT CONCERNS: We report the case of a 57-year-old man who underwent bipolar hemiarthroplasty 2 months ago caused by a left femoral neck fracture. Postoperatively, bipolar dislocation occurred thrice, and the patient showed bipolar cup dissociation during closed reduction maneuver at the recent visit. At the time of this event, no consideration was given to the shape of the prosthesis on the radiograph. DIAGNOSES: The patient was diagnosed with early bipolar cup dissociation. INTERVENTIONS: The patient underwent revision surgery to replace and reassemble the femoral head component. OUTCOMES: No further dislocation occurred following the surgery. LESSONS: To avoid dissociation of the components during closed reduction, it would be helpful to have knowledge of the "O" sign, a concentric circle shape of the prosthesis on the radiograph. LEVEL OF EVIDENCE: Level V, case report.

Surgical strategy of the treatment of atypical femoral fractures.

The atypical femoral fracture (AFF) has been attracting significant attention because of its increasing incidence; additionally, its treatment is challenging from biological and mechanical aspects. Although surgery is often required to manage complete AFFs, clear guidelines for the surgical treatment of AFFs are currently sparse. We reviewed and described the surgical treatment of AFFs and the surveillance of the contralateral femur. For complete AFFs, cephalomedullary intramedullary nailing spanning the entire length of the femur can be used. Various surgical techniques to overcome the femoral bowing common in AFFs include a lateral entry point, external rotation of the nail, and the use of a nail with a small radius of curvature, or a contralateral nail. In the case of a narrow medullary canal, severe femoral bowing, or pre-existing implants, plate fixation may be considered as an alternative. For incomplete AFFs, prophylactic fixation depends on several risk factors, such as a subtrochanteric location, presence of a radiolucent line, functional pain, and condition of the contralateral femur; the same surgical principles as those in complete AFFs can be applied. Finally, once AFF is diagnosed, clinicians should recognize the increased risk of contralateral AFFs, and close surveillance of the contralateral femur is recommended.

Current Research on the Influence of Statin Treatment on Rotator Cuff Healing.

Rotator cuff tears are a condition characterized by damage to the muscles and tendons that connect the scapula and humerus, which are responsible for shoulder rotation and arm lifting. Metabolic factors such as diabetes, thyroid disease, high cholesterol, vitamin D deficiency, obesity, and smoking have been associated with an increased risk of rotator cuff tears. Interestingly, patients with hyperlipidemia, a condition characterized by high levels of cholesterol and other fats in the blood, have been found to have a higher incidence of rotator cuff tears and breakdown of tendon matrix. As a result, statin therapy, which is commonly used to lower cholesterol levels in hyperlipidemia, has been explored as a potential treatment to improve clinical outcomes in rotator cuff tears. However, the results of preclinical and clinical studies on the effects of statins on tendon healing in rotator cuff tears are limited and not well-defined. Moreover, since hyperlipidemia and rotator cuff tears are more prevalent in older individuals, a literature review on the efficacy and safety of statin therapy in this population is needed.

Prognostic factors determining long-term outcomes of conservative treatment for acute calcific periarthritis of the hand.

Acute calcific periarthritis (ACP) of the hand is an uncommon disease that is usually self-limited. Although the conservative treatment is generally considered the primary intervention, the prognostic factors associated with long-term outcomes have yet to be identified. The purposes of this study were to investigate the long-term effects of conservative treatment and identify factors associated with long-term prognosis. We retrospectively reviewed 25 patients with a mean age of 46 years who were diagnosed with ACP of the hand and followed up over more than 2 years. Pain control with nonsteroidal anti-inflammatory drugs and activity restrictions were recommended for the initial treatment. Symptom persistence was defined as a visual analogue scale of more than 1. We compared patients with and without symptom persistence regarding potential prognostic factors such as age, gender, calcification size and type (type 1, amorphous and ill-defined; type 2, homogenous and well-defined), and joints and digits involved. Factors associated with symptom persistence were examined with multivariate analysis. At 2-year follow-up, 19 patients showed complete improvement, whereas 6 reported persistent symptoms. Symptom persistence was independently associated with the thumb involvement (odds ratio (OR), 149.77; 95% confidence interval (CI), 0.61-15.98; P = 0.02) and calcification type 2 (OR, 27.68; 95% CI, 0.50-11.08; P = 0.02). In our study, most patients with ACP of the hand reported symptom improvement with conservative treatment at 2 years of follow-up. Calcification of the thumb or calcification type (homogeneous with a well-defined margin) was independently associated with symptom persistence at 2 years.

The Wear Rate and Survivorship in Total Hip Arthroplasty Using a Third-generation Ceramic Head on a Conventional Polyethylene Liner: A Minimum of 15-year Follow-up.

Purpose: The purpose of this study was to evaluate the wear and survival rates of third-generation ceramic heads on a conventional ultra-high molecular weight polyethylene liner. Materials and Methods: A total of 160 hips (147 patients with a mean age of 55.9 years) who underwent total hip arthroplasty using the third-generation ceramic head on a conventional polyethylene liner from March 1998 to August 2003 were reviewed retrospectively. Evaluation of the wear rate for 56 hips (49 patients) followed-up for at least 15 years was performed using the PolyWare program version 8 (Draftware Developers, USA). The Kaplan-Meier survivorship was also evaluated. Results: Linear wear and volumetric wear rates were 0.11±0.47 mm/year and 32.75±24.50 mm3/year, respectively. Nine revisions were performed during the follow-up period because of cup or stem loosening. The Kaplan-Meier survival rate, using cup revision or total revision total hip arthroplasty (THA) as the endpoint of analysis, was 93.7% at 15 years and 73.6% at 20 years. Conclusion: Because all revisions were performed between 15 and 20 years in our study, surgeons should pay greater attention to patients who underwent THA with ceramic-on-polyethylene bearing from 15 years postoperatively. Contemporary alumina ceramic on highly cross-linked polyethylene could certainly be a good alternative bearing couple providing better longevity.

Open Foveal Repair of the Triangular Fibrocartilage Complex Tears Associated with Symptomatic Ulnar Styloid Non-union.

Background: Symptomatic ulnar styloid non-union can be treated by excision of the ulnar styloid fragment. For combined triangular fibrocartilage complex (TFCC) tears, several repair techniques such as arthroscopic repair, open repair to the fracture site or reconstruction using a tendon graft have been introduced. This study reports the technique and outcomes of open foveal repair of the TFCC with excision of the ulnar styloid fragment in patients with symptomatic ulnar styloid non-union and distal radioulnar joint (DRUJ) instability. Methods: Consecutive patients with symptomatic ulnar styloid non-union with TFCC tears and DRUJ instability who underwent excision of the ulnar styloid fragment and open foveal repair of the TFCC were retrospectively reviewed. After excising the ulnar styloid fragment, a capsular window was created between the triquetrum and TFCC, followed by attaching the TFCC to the fovea using three sutures through a bone tunnel from the ulnar cortex to the fovea. Additional ulnar shortening osteotomies were performed in patients with positive ulnar variance and ulnar impaction test. The outcomes were evaluated in terms of DRUJ stability and the Quick Disabilities of the Arm, Shoulder and Hand (DASH) scores. Results: In total, 21 patients with a mean age of 40 were enrolled in the study. All patients demonstrated DRUJ stability at a mean follow-up duration of 14 months. The mean Quick DASH score significantly improved from 18.9 ± 11.7 to 2.5 ± 4.1 (p < 0.05). Eleven patients underwent combined ulnar shortening osteotomies, and no difference in the Quick DASH score was found between patients who underwent ulnar shortening osteotomy and those who did not. Conclusions: This study demonstrates that open foveal repair of the TFCC with ulnar styloid fragment excision is an effective strategy to surgically treat patients with symptomatic ulnar styloid non-union with TFCC tear and DRUJ instability. Level of Evidence: Level III (Therapeutic).

The Natural History of Kienböck's Disease Diagnosed at More than 50 Years of Age.

Background: Previous literatures suggest that the prognosis of Kienböck's disease might be favorable despite no surgery if it is diagnosed in late age, but the evidence is not clear. The aim of this study was to determine the radiographic and clinical progression of Kienböck's disease diagnosed at more than 50 years of age. Methods: Data of 27 patients diagnosed with Kienböck's disease at more than 50 years of age between 2000 and 2016 were investigated. During the study period, no treatment, either surgical or nonsurgical, was applied. We explained to the patients that the affected lunate was not expected to collapse further if found late in age. Annual visits were recommended, through which radiographic and clinical observation was made. We assessed changes in Stahl index and radioscaphoid angle between the initial assessment and the final follow-up, and clinical assessment was made using pain in visual analog scale (VAS) and Dornan's criteria. Results: Initially, 2 patients were in Lichtman stage 1, 6 in stage 2, 5 in stage 3A, 11 in stage 3B, and 3 in stage 4. Radiographic follow-up of at least 5 years (mean, 7.8 years) was made in 14 patients, whose Stahl index and radioscaphoid angle did not differ significantly from their initial measurements. Arthritic appearance was not found, and progression in the Lichtman stage was detected in 1 lunate, from 3A to 3B. Despite no surgical treatment for an average of 7.5 years (range, 5.0-15.7 years) of observation period in the 27 patients, average pain in VAS improved from 3.5 (range, 1-7) to 0.8 (range, 0-2), with excellent or good clinical status by Dornan's criteria. Conclusions: Our study suggests that Kienböck's disease diagnosed at more than 50 years of age can follow a benign natural course in radiographic and clinical aspects. Therefore, surgical interventions should be considered carefully in this age group.

Comparison of the conventional Henry approach and trans-flexor carpi radialis approach for the treatment of distal radius fracture: A retrospective cohort study.

Few studies have compared the clinical outcomes of the conventional Henry approach and trans-flexor carpi radialis (FCR) approach. The purpose of this study was to compare the clinical and radiologic outcomes of the conventional Henry approach and trans-FCR approach for the treatment of distal radius fractures. We compared 20 wrists that underwent the conventional Henry approach with 20 wrists that underwent the trans-FCR approach for open reduction and internal fixation of distal radius fracture. The clinical and radiological parameters were checked at 3 months, 6 months, and 1 year after surgery. A visual analogue scale score, the modified Mayo wrist score, range of motion, and grip strength were collected. In addition, tenderness in the area of the FCR tendon were assessed. Regarding radiologic evaluations, the radial inclination, radial height, volar tilt, and ulna variance were measured. In the trans-FCR approach group, 15 patients complained of tenderness in the area of the FCR tendon at 3 months after surgery, which was significantly higher than those of conventional Henry approach group (P < .05). In the conventional Henry approach group, the tenderness had resolved spontaneously by 1 year after surgery in 19 patients. The trans-FCR approach can cause discomfort such as tenderness to the area of the FCR tendon compared to the conventional Henry approach, but there is no significant difference in the final clinical and radiologic outcomes.

Clinical Manifestations, Diagnosis and Management of Synovial Fistula Associated Lateral Ankle Sprain or Instability: A Retrospective Study of 19 Surgically Confirmed Patients.

We aimed to investigate the preoperative history, clinical manifestations, imaging findings, and postoperative clinical outcomes for patients with surgically confirmed synovial fistula around the ankle joint. 19 consecutive patients who were confirmed to have synovial fistula in the surgical field were enrolled in this study. Medical records of all patients in terms of preoperative details, operative findings, and postoperative outcomes at 1 year after the surgery were retrieved. As a diagnostic modality, the normal saline test or MRI was used. Intraoperatively, the synovial fistula was repaired with the capsuloligamentous repair or additional periosteal augmentation. All patients had a history of ankle sprain prior to symptoms and showed positive results in the saline load test. One patient had recurred symptom after the surgery, so needed a revisional periosteal augmentation. At 1 year follow-up period, the average Foot ankle outcome score was 87.65 and no surgery-related complication was detected. Synovial fistula of the ankle joint needs to be taken into consideration as a possible complication in patients with ankle sprain history and recurrent joint swelling. The saline load test would be useful for its diagnosis, and treatment should be focused on the complete closure of capsular opening along with restoration of its surrounding pathologic conditions.

Pyruvate dehydrogenase kinase 4 promotes ubiquitin-proteasome system-dependent muscle atrophy.

BACKGROUND: Muscle atrophy, leading to muscular dysfunction and weakness, is an adverse outcome of sustained period of glucocorticoids usage. However, the molecular mechanism underlying this detrimental condition is currently unclear. Pyruvate dehydrogenase kinase 4 (PDK4), a central regulator of cellular energy metabolism, is highly expressed in skeletal muscle and has been implicated in the pathogenesis of several diseases. The current study was designed to investigated and delineate the role of PDK4 in the context of muscle atrophy, which could be identified as a potential therapeutic avenue to protect against dexamethasone-induced muscle wasting. METHODS: The dexamethasone-induced muscle atrophy in C2C12 myotubes was evaluated at the molecular level by expression of key genes and proteins involved in myogenesis, using immunoblotting and qPCR analyses. Muscle dysfunction was studied in vivo in wild-type and PDK4 knockout mice treated with dexamethasone (25 mg/kg body weight, i.p., 10 days). Body weight, grip strength, muscle weight and muscle histology were assessed. The expression of myogenesis markers were analysed using qPCR, immunoblotting and immunoprecipitation. The study was extended to in vitro human skeletal muscle atrophy analysis. RESULTS: Knockdown of PDK4 was found to prevent glucocorticoid-induced muscle atrophy and dysfunction in C2C12 myotubes, which was indicated by induction of myogenin (0.3271 ± 0.102 vs 2.163 ± 0.192, ****P < 0.0001) and myosin heavy chain (0.3901 ± 0.047 vs. 0.7222 ± 0.082, **P < 0.01) protein levels and reduction of muscle atrophy F-box (10.77 ± 2.674 vs. 1.518 ± 0.172, **P < 0.01) expression. In dexamethasone-induced muscle atrophy model, mice with genetic ablation of PDK4 revealed increased muscle strength (162.1 ± 22.75 vs. 200.1 ± 37.09 g, ***P < 0.001) and muscle fibres (54.20 ± 11.85% vs. 84.07 ± 28.41%, ****P < 0.0001). To explore the mechanism, we performed coimmunoprecipitation and liquid chromatography-mass spectrometry analysis and found that myogenin is novel substrate of PDK4. PDK4 phosphorylates myogenin at S43/T57 amino acid residues, which facilitates the recruitment of muscle atrophy F-box to myogenin and leads to its subsequent ubiquitination and degradation. Finally, overexpression of non-phosphorylatable myogenin mutant using intramuscular injection prevented dexamethasone-induced muscle atrophy and preserved muscle fibres. CONCLUSIONS: We have demonstrated that PDK4 mediates dexamethasone-induced skeletal muscle atrophy. Mechanistically, PDK4 phosphorylates and degrades myogenin via recruitment of E3 ubiquitin ligase, muscle atrophy F-box. Rescue of muscle regeneration by genetic ablation of PDK4 or overexpression of non-phosphorylatable myogenin mutant indicates PDK4 as an amenable therapeutic target in muscle atrophy.

Comparison of the effectiveness of extensor muscle strengthening exercise by itself, exercise with polydeoxyribonucleotide injection, and exercise with extracorporeal shockwave therapy in lateral epicondylitis: a randomized controlled trial.

BACKGROUND: Extensor muscle strengthening exercises with counterforce braces (EX) is a conventional conservative treatment for lateral epicondylitis (LE) of the elbow. In addition, polydeoxyribonucleotide (PDRN) or extracorporeal shockwave therapy (ESWT) has been recently used for LE. METHODS: Sixty-three patients with chronic LE participated in this study and randomly allocated in three groups (G1: EX, G2: EX+PDRN injection, and G3: EX+ESWT). All of the three groups were taught to perform EX at the first out-patient department (OPD) visit. Group 2 was injected with 3 mL PDRN (5.625 mg/3 mL), while group 3 received ESWT at the first OPD visit. Visual analog scale pain score, Mayo elbow performance score (MEPS), and ultrasonographic examination were checked before, 6 weeks, and 12 weeks after the treatments. RESULTS: Overall functional scores and ultrasonographic findings in all three groups improved after treatment. The mean MEPS in group 2 improved more than groups 1 and 3 at 6 weeks (G1, 56.9>62.4; G2, 54.3>65.0; G3, 55.7>62.6), and more than group 1 at 12 weeks (G1, 56.9>67.9; G2, 54.3>73.6). The mean common extensor tendon depth (CETD) on ultrasonography in group 2 increased more than groups 1 and 3 at 6 and 12 weeks (6 weeks: G1, 0.385>0.386; G2, 0.332>0.392; G3, 0.334>0.357; 12 weeks: G1, 0.385>0.409; G2, 0.332>0.438; G3, 0.334>0.405 [cm]). CONCLUSIONS: PDRN injections combined with EX exhibited a greater improvement in mean MEPS and mean CETD compared to EX only or EX combined with ESWT for LE within the 12 weeks follow-up.

Upper Limb Reconstruction in Tetraplegic Patients: A Primer for Spinal Cord Injury Specialists.

Cervical spinal cord injury (SCI) often causes debilitating loss of function of the upper limb. Upper extremity reconstruction surgery can restore some of the upper limb function in tetraplegic patients with SCI. The procedures are typically muscle-tendon unit transfer surgeries, which redistribute the remaining functional muscles to restore active elbow extension, key grip, and finger grasping. In addition to the tendon transfer surgeries, nerve transfers have emerged recently and are showing promising results. However, despite more than half of the tetraplegic patients can benefit from upper limb surgery, only a few of them receive the procedures. This missed opportunity may be due to the lack of communication between SCI specialists and hand surgeons, or the lack of awareness of such options among the specialists and patients. In this review, we provide a basic overview of upper limb reconstruction in tetraplegic patients with target audience of SCI specialists for their better understanding of the basic concept of surgery and information for patient consultation before referring to hand surgeons.

Where is the Target Point to Prevent Cortical Hinge Fracture in Medial Closing-Wedge Distal Femoral Varus Osteotomy?

The purpose of this study was to investigate whether the location of the hinge affects the incidence of hinge fracture during medial closing-wedge distal femoral varus osteotomy (DFVO). Twenty knees from 10 fresh-frozen human cadavers (mean age, 75 ± 17 years) were used to perform uniplanar medial closing-wedge DFVO with a 7-mm wedge. Each specimen was randomly assigned to either group A (supracondylar hinge) or group B (lateral condylar hinge). The incidence of hinge fracture and stability was compared between both groups after uniplanar medial closing-wedge DFVO. In group A, 8 of 10 knees had a lateral cortex fracture during closure of the osteotomy gap, and all fractured knees were unstable. Two knees with an intact lateral cortical hinge showed stability under manual valgus and varus forces. After intentional breakage of the lateral cortical hinge, both knees were found to be unstable under the same force. In group B, 2 of 10 knees had a lateral cortex fracture, and 8 knees had no fractures. All specimens were found to be stable under manual valgus and varus forces. After intentional breakage of the lateral cortical hinge in group B, 2 knees were unstable, while 8 knees remained stable. This study showed a significantly higher incidence of lateral cortical hinge fracture and instability in group A than in group B during closure of the osteotomy gap.