The application of a dual-lead locking screw could enhance the reduction and fixation stability of the proximal humerus fractures: a biomechanical evaluation.

Introduction: Bicortical screw fixation, which penetrates and fixes the near and far cortex of bone, has been conventionally used to achieve compressive fixation for fracture using screws. Open reduction and internal fixation using the locking plate are widely used for treating proximal humerus fractures. However, minimal contact between the bone and the locking plate can lead to an insufficient reduction. Theoretically, a dual-lead locking screw with different leads for the screw head and body could enhance the reduction and fixation stability of fragments in proximal humeral fractures without bicortical fixation, and achieve additional compression at the bone-plate-screw interface. This study assessed the insertion mechanics of the lead ratio of the dual-lead locking screw and its effect on the fixation stability of the proximal humerus fracture. Methods: A Multi-Fix® locking plating system composed of ∅ 3.5 mm locking screws and a locking plate was used to make a locked plating for Sawbone bone blocks and fourth-generation composite humeri. Two different types of Sawbone bone blocks were used to simulate the osteoporotic (10 PCF) and normal cancellous (20 PCF) bones. The lead of the screw head thread (Lhead) was 0.8 mm, and that of the screw body (Lbody) was 0.8, 1.25, 1.6, 2.0, and 2.4 mm, whose lead ratios (Rlead=Lbody/Lhead) were 1.0, 1.56, 2.0, 2.5, and 3.0, respectively. Results: The dual-lead locking screw elevated the compression between the locking plate and the bone. The elevation in the compression due to the dual-lead thread became weaker for the cancellous bone when the lead of the screw body was more than twice that of the screw head. The plate/humerus compression with strong bone quality withstood higher dual-lead-driven compression. Discussion: A dual-lead locking screw of Lbody=1.25mm (Rlead=1.56) is recommended for maximum rotational stability for the locked humerus plating. The screws with over Lbody=1.6mm (Rlead=2) have no advantage in terms of the failure torque and maximum torsional deformation. Any locking dual-lead screw with a body thread lead of <1.6 mm (Rlead=2) can be used without the risk of bone crush when surgeons require additional compression to the locked cancellous bone plating.

Spontaneous resolution of spinoglenoid ganglion cyst: a case series.

BACKGROUND: Spontaneous resolution of a spinoglenoid notch ganglion cyst (SGC) without surgical treatment has been rarely reported; however, we have encountered this phenomenon occasionally. Therefore, we aimed to describe a case series of consecutive patients with SGC in whom it spontaneously resolved without surgical treatment. METHODS: We retrospectively reviewed 12 patients with magnetic resonance imaging (MRI)-confirmed SGC in whom it resolved without surgical treatment between January 2011 and March 2023. We included patients without abnormally increased signal intensity or muscle atrophy due to denervation from suprascapular neuropathy on MRI. Resolution of the SGC was confirmed via MRI or ultrasound at the follow-up visit, and suprascapular neuropathy was assessed using electromyography and nerve conduction studies when needed. For functional assessments, the visual analog scale for pain and active range of motion of the shoulder were used to compare pre and postresolution follow-ups. RESULTS: Eleven men and 1 woman with a median age of 54.0 years (interquartile range [IQR] 37.0-65.3) were included in this study. The SGCs resolved spontaneously at a median of 13.2 months with an IQR of 8.2-23.0 after initial evaluation using MRI. The SGCs were multiloculated cysts with superior labrum anterior and posterior II-IX lesions, with a median diameter of 2.5 cm (IQR 2.0-2.8). The median visual analog scale for pain (pre-resolution 5.0 [IQR 4.0-7.0] vs postresolution 1.0 [IQR 0.0-1.0], P = .002) and internal rotation at the back (preresolution 8.0 [IQR 7.0-10.3] vs postresolution 7.5 [IQR 7.0-8.0], P = .034) were significantly improved after the resolution. CONCLUSIONS: Surgical treatment may not be necessary in all cases of SGC. Nonsurgical treatment may be a viable option in the absence of suprascapular nerve involvement or superior labrum anterior and posterior-related physical findings.

Recombinant Human Parathyroid Hormone Biocomposite Promotes Bone-to-Tendon Interface Healing by Enhancing Tenogenesis, Chondrogenesis, and Osteogenesis in a Rabbit Model of Chronic Rotator Cuff Tears.

PURPOSE: To investigate the effect of recombinant human parathyroid hormone (rhPTH) biocomposite on bone-to-tendon interface (BTI) healing for surgical repair of a chronic rotator cuff tear (RCT) model of rabbit, focusing on genetic, histologic, biomechanical and micro-computed tomography (CT) evaluations. METHODS: Sixty-four rabbits were equally assigned to the 4 groups: saline injection (group A), nanofiber sheet alone (group B), rhPTH-soaked nanofiber sheet (nanofiber sheet was soaked with rhPTH, group C), and rhPTH biocomposite (rhPTH permeated the nanofiber sheet by coaxial electrospinning, group D). The release kinetics of rhPTH (groups C and D) was examined for 6 weeks in vitro. Nanofiber scaffolds were implanted on the surface of the repair site 6 weeks after the induction of chronic RCT. Genetic and histologic analyses were conducted 4 weeks after surgery. Furthermore, genetic, histologic, biomechanical, micro-CT, and serologic analyses were performed 12 weeks after surgery. RESULTS: In vivo, group D showed the highest collagen type I alpha 1 (COL1A1), collagen type III alpha 1 (COL3A1), and bone morphogenetic protein 2 (BMP-2) messenger RNA (mRNA) expression levels (all P < .001) 4 weeks after surgery; however, there were no differences between groups at 12 weeks postsurgery. After 12 weeks postsurgery, group D showed better collagen fiber continuity and orientation, denser collagen fibers, more mature bone-to-tendon junction, and greater fibrocartilage layer formation compared with the other groups (all P < .05). Furthermore, group D showed the highest load-to-failure rate (28.9 ± 2.0 N/kg for group A, 30.1 ± 3.3 N/kg for group B, 39.7 ± 2.7 N/kg for group C, and 48.2 ± 4.5 N/kg for group D, P < .001) and micro-CT outcomes, including bone and tissue mineral density, and bone volume/total volume rate (all P < .001) at 12 weeks postsurgery. CONCLUSIONS: In comparison to rhPTH-soaked nanofiber sheet and the other control groups, rhPTH biocomposite effectively accelerated BTI healing by enhancing the mRNA expression levels of COL1A1, COL3A1, and BMP-2 at an early stage and achieving tenogenesis, chondrogenesis, and osteogenesis at 12 weeks after surgical repair of a chronic RCT model of rabbit. CLINICAL RELEVANCE: The present study might be a transitional study to demonstrate the efficacy of rhPTH biocomposites on BTI healing for surgical repair of chronic RCTs as an adaptable polymer biomaterial in humans.

Far-Infrared Radiation to Improve Clinical Outcomes after Arthroscopic Rotator Cuff Repair: A Prospective Randomized Comparative Clinical Study.

Background: The efficacy of far-infrared radiation (FIR) after rotator cuff repair has not been demonstrated yet. The aim of this study was to evaluate the effects of postoperatively applied FIR with regard to early pain, range of motion (ROM), and tendon-to-bone healing after arthroscopic rotator cuff repair. Methods: A total of 64 consecutive patients who underwent arthroscopic rotator cuff repair with small- to medium-sized tears were enrolled in this prospective comparative study and randomly divided into an FIR group (n = 31) and a control group (n = 33). In the FIR group, FIR using a radiator device (Aladdin-H) was applied for 30 minutes per session twice daily from the first postoperative day. This application lasted for 10 weeks during the postoperative period. Clinical outcomes were assessed using a visual analog scale for pain (pVAS) at 5 weeks and ROM at 3 and 6 months postoperatively. Functional scores were evaluated at 6 months postoperatively. Healing of the repaired rotator cuff was also evaluated using ultrasonography at 3 months and magnetic resonance imaging at 6 months postoperatively. Results: In both groups, clinical and functional outcomes were improved up to 6 months compared with preoperative values. At 5 weeks and 3 months postoperatively, the average pVAS was significantly lower in the FIR group than in the control group (1.7 ± 1.0 vs. 2.8 ± 1.4; p = 0.002 at 5 weeks, 2.4 ± 1.3 vs. 3.2 ± 1.8; p = 0.041 at 3 months). However, there was no significant difference in ROM, functional score, or healing rate between two groups at each follow-up time point. Conclusions: The application of FIR after arthroscopic rotator cuff repair could be a safe and effective procedure to decrease postoperative pain, especially in the early postoperative period. This effective application of FIR can be considered to facilitate painless rehabilitation in the postoperative period after arthroscopic rotator cuff repair.

Arthroscopic transosseous anchorless rotator cuff repair reduces bone defects related to peri-implant cyst formation: a comparison with conventional suture anchors using propensity score matching.

BACKGROUND: The transosseous anchorless repair (ToR) technique was recently introduced to avoid suture anchor-related problems. While favorable outcomes of the ToR technique have been reported, no previous studies on peri-implant cyst formation with the ToR technique exist. Therefore, this study compared the clinical outcomes and prevalence of peri-implant cyst formation between the ToR technique and the conventional transosseous equivalent technique using suture anchors (SA). METHODS: Cases with arthroscopic rotator cuff repair (ARCR) between 2016 and 2018 treated with the double-row suture bridge technique were retrospectively reviewed. Patients were divided into ToR and SA groups. To compare clinical outcomes, 19 ToR and 57 SA cases without intraoperative implant failure were selected using propensity score matching (PSM). While intraoperative implant failure rate was analyzed before PSM, retear rate, peri-implant cyst formation rate, and functional outcomes were compared after PSM. RESULTS: The intraoperative implant failure rate (ToR, 8% vs. SA, 15.3%) and retear rate (ToR, 5.3% vs. SA, 19.3%) did not differ between the two groups (all P>0.05). However, peri-implant cysts were not observed in the ToR group, while they were observed in 16.7% of the SA group (P=0.008). Postoperative functional outcomes were not significantly different between the two groups (all P>0.05). CONCLUSIONS: The ToR technique produced comparable clinical outcomes to conventional techniques. Considering the prospect of potential additional surgeries, the absence of peri-implant cyst formation might be an advantage of ToR. Furthermore, ToR might reduce the medical costs related to suture anchors and, thereby, could be a useful option for ARCR. Level of evidence: III.

Can convertible metal-backed glenoid components replace cemented polyethylene glenoid components in anatomical total shoulder arthroplasty?

BACKGROUND: Anatomical total shoulder arthroplasty (aTSA) has been used to manage degenerative diseases such as primary osteoarthritis. An increase in the use of this procedure has led to several developments in humeral and glenoid components to improve patient outcomes. This study aimed to compare clinical and radiological outcomes of the newly-introduced convertible metal-backed glenoid components with cemented polyethylene glenoid components in aTSA, and to determine whether the new component would be comparable to a conventional one for reducing the burden of future revision or conversion surgeries. METHODS: Medical records of fifty patients who underwent aTSA with at least two years of follow-up were retrospectively reviewed. Eighteen patients received convertible metal-backed glenoid components with vitamin E1-coated liner (MB group), while thirty-two patients received conventional cemented polyethylene glenoid components (PE group). Pre- and postoperative clinical and radiological outcomes (acromion-greater tuberosity angle [AGA] and humeral lateral offset [LO]) at final follow-up were assessed. Radiolucent lines (RLLs) and loosening around the humeral and glenoid components were also evaluated. RESULTS: Clinical outcomes improved after surgery in both groups (all p < 0.001). The arc of rotation measured by AGA improved postoperatively in both groups (all p < 0.001), and AGA and LO were not different according to the type of glenoid components (all p > 0.05). Overall complication rates including RLLs of PE and MB groups were 43.8% (14/32) and 16.7% (3/18), respectively (p = 0.031). Although the PE group had more RLLs than did the MB group (p < 0.05), related symptoms and/or glenoid implant loosening were not observed in both groups. Subscapularis failure occurred in two patients in the PE group and in one in the MB group. CONCLUSION: The convertible metal-backed glenoid implant with vitamin E1-coated liner may be a good alternative for considering the potential for an easier conversion to reverse total shoulder arthroplasty.

The correlation of the spinoglenoid ganglion cyst size with the electrophysiological alterations of suprascapular nerve and the rotator cuff muscle power.

BACKGROUND: Although various treatment options are available for spinoglenoid cyst, including conservative and surgical methods, there is no standard guideline for its surgical decompression. Thus, the purpose of the study was to correlate the size of the spinoglenoid notch ganglion cyst (GC) as revealed by magnetic resonance imaging (MRI) with electrophysiological alterations, muscle power, and pain severity, and to estimate a cut-off value of cyst size to perform a decompression. METHODS: Between January 2010 and January 2018, the patients with a GC at the spinoglenoid notch diagnosed on MRI, and who had a minimum follow-up of 2 years after the decompression were included. Maximum cyst diameter as measured on MRI was used for comparison. Electromyography (EMG) and nerve conduction velocity (NCV) studies were performed before the surgery. Peak torque deficit (PTD) percentage compared to opposite shoulder was calculated preoperatively and at 1 year after surgery. Pain severity was estimated using visual analogue scale (VAS) preoperatively. RESULTS: Ten (50%) of 20 patients with GC > 2.2 cm and 1 (5.9%) of 17 patients with GC < 2.2 cm showed EMG/NCV abnormalities (p = 0.019). There was a correlation between the cyst size and the positive EMG/NCV findings (Correlation coefficient (CC) = 0.535, p < 0.001). The preoperative peak torque deficit on the external rotation was correlated with the positive EMG/NCV findings (CC = 0.373, p = 0.021). The PTD was improved significantly at 1 year postoperatively in patients with a GC size >2.2 cm (p = 0.029). The cyst size was not related to the preoperative pain VAS and muscle power. CONCLUSIONS: The spinoglenoid cyst size >2.2 cm, but not pain severity or muscle power, correlates with the positive finding of EMG for compressive suprascapular neuropathy. The GC size >2.2 cm can be a reference to decide the need of decompression surgery. LEVEL OF EVIDENCE: IV, case series.

Posterior Rotator Cuff Tears: Is Extracorporeal Shockwave Therapy a Risk Factor?

Background: Negative effects of extracorporeal shock wave therapy (ESWT) on vulnerable tendon structures have been reported. Meanwhile, tears of the posterior rotator cuff tendon, which is thinner than the anterior, are not common, and the clinical features remain poorly understood. Therefore, we evaluated the relationship between ESWT and posterior rotator cuff tears (RCTs) by investigating the risk factors. Methods: Of 294 patients who underwent rotator cuff repair between October 2020 and March 2021, a posterior RCT more than 1.5 cm from the biceps tendon or an isolated infraspinatus tear was identified in 24 (8.1%, group P). Sixty-two patients (21%) with an anterior RCT within 1.5 cm of the biceps tendon were analyzed as a control group (group A). Preoperative clinical characteristics were assessed to determine the risk factors of posterior RCTs. Results: Calcific deposits were more frequently observed in group P (n = 7, 29.2%) than group A (n = 6, 9.7%, p = 0.024). Further, those in group P were more likely to undergo ESWT (n = 18, 75.0%) than those in group A (n = 15, 24.2%, p < 0.001). Of these, 7 patients experiencing calcific tendinitis from group P (29.2%) and 4 from group A (6.5%, p = 0.005) underwent ESWT for calcification removal. Furthermore, 11 patients experiencing tendinopathy from group P (45.8%), and 11 from group A (17.7%, p = 0.007) underwent ESWT for pain relief. The mean level of fatty infiltration of the supraspinatus was significantly higher in group A than group P (1.8 vs. 1.0, p < 0.001). Conclusions: Since a high prevalence rate of posterior RCTs was related to ESWT, it should be carefully considered when treating calcific tendinitis or pain in patients experiencing tendinopathy.

Subacromial notching after reverse total shoulder arthroplasty.

BACKGROUND: Scapular notching is a well-known postoperative complication of reverse total shoulder arthroplasty (RTSA). However, subacromial notching (SaN), a subacromial erosion caused by repeated abduction impingement after RTSA, has not been previously reported in a clinical setting. Therefore, this study aimed to assess the risk factors and functional outcomes of SaN after RTSA. METHODS: We retrospectively reviewed the medical records of 125 patients who underwent RTSA with the same design between March 2014 and May 2017 and had at least 2 years of follow-up. SaN was defined as subacromial erosion observed at the final follow-up but not on the X-ray 3 months after surgery. Radiologic parameters representing the patient's native anatomy and degrees of lateralization and/or distalization during surgery were evaluated using preoperative and 3 months postoperative X-rays. The visual analogue scale of pain, active range of motion, and American Shoulder and Elbow Surgeons score were assessed preoperatively and at the final follow-up to evaluate the functional outcomes of SaN. RESULTS: SaN occurred in 12.8% (16/125) of enrolled patients during the study period. Preoperative center of rotation-acromion distance (P = .009) and postoperative humerus lateralization offset, which evaluated the degree of lateralization after RTSA (P = .003), were risk factors for SaN. The preoperative center of rotation-acromion distance and postoperative humerus lateralization cutoff values were 14.0 mm and 19.0 mm, respectively. The visual analogue scale of pain (P = .01) and American Shoulder and Elbow Surgeons score (P = .04) at the final follow-up were significantly worse in patients with SaN. CONCLUSIONS: SaN might adversely affect postoperative clinical outcomes. As SaN correlated with patients' anatomical characteristics and degree of lateralization during RTSA, the implant's degree of lateralization should be adjusted according to the patient's own anatomical characteristics.

Implant selection for successful reverse total shoulder arthroplasty.

Reverse total shoulder arthroplasty (RTSA) emerged as a new concept of arthroplasty that does not restore normal anatomy but does restore function. It enables the function of the torn rotator cuff to be performed by the deltoid and shows encouraging clinical outcomes. Since its introduction, various modifications have been designed to improve the outcome of the RTSA. From the original cemented baseplate with peg or keel, a cementless baseplate was designed that could be fixed with central and peripheral screws. In addition, a modular-type glenoid component enabled easier revision options. For the humeral component, the initial design was an inlay type of long stem with cemented fixation. However, loss of bone stock from the cemented stem hindered revision surgery. Therefore, a cementless design was introduced with a firm metaphyseal fixation. Furthermore, to prevent complications such as scapular notching, the concept of lateralization emerged. Lateralization helped to maintain normal shoulder contour and better rotator cuff function for improved external/internal rotation power, but excessive lateralization yielded problems such as subacromial notching. Therefore, for patients with pseudoparalysis or with risk of subacromial notching, a medial eccentric tray option can be used for distalization and reduced lateralization of the center of rotation. In summary, it is important that surgeons understand the characteristics of each implant in the various options for RTSA. Furthermore, through preoperative evaluation of patients, surgeons can choose the implant option that will lead to the best outcomes after RTSA.

Serum Vitamin D Level Correlations With Tissue Vitamin D Level and Muscle Performance Before and After Rotator Cuff Repair.

BACKGROUND: There is a lack of studies about serum and tissue vitamin D levels of the rotator cuff muscle on muscle power, fatty degeneration, and healing failure after rotator cuff repair (RCR). Furthermore, no studies have evaluated vitamin D receptor proteins in the rotator cuff that show a close association with serum vitamin D levels. PURPOSE: To evaluate the correlations between serum vitamin D and tissue vitamin D as well as perioperative variables of arthroscopic RCR. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: From March 2017 to October 2017, a total of 36 patients who underwent RCR were prospectively enrolled, and supraspinatus muscle tissue was obtained during surgery to analyze tissue vitamin D levels. Serum vitamin D levels were checked preoperatively and at 6 months and 1 year postoperatively. Tissue vitamin D levels were assessed using liquid chromatography, and the vitamin D receptor was measured by western blotting. Isokinetic muscle performance test (IMPT; peak torque and torque deficiency compared with the opposite shoulder) results and fatty degeneration of the rotator cuff using the Goutallier classification were assessed preoperatively and at 1 year after surgery. The American Shoulder and Elbow Surgeons score and Constant score were collected at 2 years after surgery. Healing failure of the repaired rotator cuff was analyzed by magnetic resonance imaging at 1 year after surgery. RESULTS: Overall, only three patients (8.3%) had serum vitamin D sufficiency (>20 ng/mL). Among 36 patients, 26 patients returned for their 1-year follow-up. Lower preoperative serum vitamin D levels resulted in lower serum vitamin D levels at 6 months and 1 year postoperatively (all P < .05). Lower preoperative and 1-year postoperative serum vitamin D levels resulted in more torque deficiency on the IMPT in abduction than higher preoperative and 1-year postoperative serum vitamin D levels (all P < .05). Tissue vitamin D levels had a strong correlation with preoperative serum vitamin D levels (P = .001). Lower tissue vitamin D levels were associated with lower peak torque on the IMPT in abduction (P = .043) and a tendency of lower peak torque on the IMPT in external rotation (P = .077) at 1 year postoperatively. There was no correlation between tissue and serum vitamin D levels and functional outcomes, fatty degeneration, and healing failure after surgery (all P > .05). The vitamin D receptor showed no correlation with any variables (all P > .05). CONCLUSION: Lower preoperative serum vitamin D levels had a strong correlation with lower tissue vitamin D levels and lower serum vitamin D levels at 1 year after surgery. Furthermore, the patients with lower serum vitamin D levels showed more weakness of muscle power perioperatively. The results of this study emphasized the association between vitamin D levels and rotator cuff muscle power.

Clinical outcomes of reverse shoulder arthroplasty and rotator cuff repair in patients with massive rotator cuff tears without osteoarthritis: comparison using propensity score matching.

BACKGROUND: The optimal management for massive rotator cuff tears (MRCTs) without osteoarthritis (OA) remains controversial. The purpose of this study was to evaluate and compare the clinical outcomes of reverse shoulder arthroplasty (RSA) vs. rotator cuff repair (RCR) in patients with MRCTs without OA. METHODS: We conducted a retrospective data analysis of 68 patients treated for MRCTs via RSA and 215 patients treated for MRCTs via arthroscopic RCR between January 2014 and April 2019. Through propensity score matching, patients were matched for sex, age, tear size, and global fatty degeneration index. Thirty-nine patients in each group were included, and all patients had completed minimal 2-year follow-up. Postoperative radiologic evaluations of healing failure were performed. The visual analog scale score for pain, range of motion, and functional outcome measures including the American Shoulder and Elbow Surgeons score, QuickDASH (short version of Disabilities of the Arm, Shoulder and Hand questionnaire) score, Simple Shoulder Test score, and Constant score were assessed and compared between the 2 groups. RESULTS: Healing failure was observed in 10 patients in the RCR group (32.3%). No statistically significant differences in preoperative range of motion and functional scores were found between the RCR and RSA groups. Both groups showed significant pain relief and functional improvement at final follow-up. Patients in the RCR group showed significantly greater forward elevation (156.4° ± 23.8° vs. 139.7° ± 22.4°, P < .001) and internal rotation (thoracic vertebra, T8.2 ± 1.2 vs. T9.7 ± 2.6, P = .001). The average American Shoulder and Elbow Surgeons score was 88.3 ± 12.2 in the RCR group and 81.8 ± 16.1 in the RSA group (P = .045). The QuickDASH score was significantly higher in the RCR group (P = .019). A significantly higher Simple Shoulder Test score (9.7 ± 2.8 vs. 8.1 ± 3.0, P = .01) and a significantly higher Constant score (67.2 ± 6.5 vs. 63.2 ± 7.1, P = .011) were seen in the RCR group. CONCLUSION: Both RSA and RCR are effective and reliable treatment options for MRCTs without OA. However, the RCR group showed better shoulder function improvement than the RSA group. Considering the possible implications of RSA, RCR should be referred to as a first-line treatment option for patients with MRCTs without OA with proper indications.

Retear After Arthroscopic Rotator Cuff Repair Results in Functional Outcome Deterioration Over Time.

PURPOSE: This study aimed to evaluate the effect of retear on long-term functional outcomes and glenohumeral joint osteoarthritis (OA) progression after arthroscopic rotator cuff repair (ASRCR). METHODS: We retrospectively reviewed 201 patients who underwent ASRCR and were followed up for at least 5 years. Rotator cuff tendon structural integrity was evaluated using magnetic resonance imaging and/or ultrasonography. Pain, active range of motion, and the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) were evaluated for functional outcomes. To evaluate deterioration over time, the minimal clinically important difference value of pain and ASES were used. RESULTS: The mean follow-up period was 8.6 ± 2.2 years and overall retear rate was 21.4%. OA progression was strongly associated with retear (odds ratio 5.1, P < .001). Functional outcomes at the 2-year postoperative follow-up significantly improved compared to the preoperative status (all P < .017), regardless of retear. However, the retear group presented worse functional outcomes at the final follow-up (pain: 3.1 ± 2.6; ASES: 72.0 ± 17.4) than at the 2-year postoperative follow-up (pain: 1.2 ± 2.3, P = .014; ASES: 91.1 ± 9.9, P= .015) than the healed tendon group at final follow-up (pain: .6 ± 1.7; P < .001; ASES 95.5 ± 11.8; P < .001). The time for deterioration of pain (healed group vs. retear group: 5.5 ± 0.5 vs. 10.6 ± 0.4 years; P < .001) and ASES (healed group vs. retear group: 7.5 ± 0.5 vs. 12.8 ± 0.2 years; P < .001) decreased in the retear group. CONCLUSIONS: The functional status improved after ASRCR in short- and long-term follow-up, regardless of retear. However, retear was strongly associated with OA progression, and long-term functional outcomes deteriorated over time in retear cases, which was not observed during short-term follow-up. STUDY DESIGN: III, retrospective cohort study.

Allogeneic Dermal Fibroblasts Improve Tendon-to-Bone Healing in a Rabbit Model of Chronic Rotator Cuff Tear Compared With Platelet-Rich Plasma.

PURPOSE: To compare the effects of allogeneic dermal fibroblasts (ADFs) and platelet-rich plasma (PRP) on tendon-to-bone healing in a rabbit model of chronic rotator cuff tear. METHODS: Thirty-two rabbits were divided into 4 groups (8 per group). In 2 groups, the supraspinatus tendon was detached and was left as such for 6 weeks. At 6 weeks after creating the tear model, we performed transosseous repair with 5 × 106 ADFs plus fibrin injection in the left shoulder and PRP plus fibrin in the right shoulder. The relative expression of the COL1, COL3, BMP2, SCX, SOX9, and ACAN genes was assessed at 4 weeks (group A) and 12 weeks (group B) after repair. Histologic and biomechanical evaluations of tendon-to-bone healing at 12 weeks were performed with ADF injection in both shoulders in group C and PRP injection in group D. RESULTS: At 4 weeks, COL1 and BMP2 messenger RNA expression was higher in ADF-injected shoulders (1.6 ± 0.8 and 1.0 ± 0.3, respectively) than in PRP-injected shoulders (1.0 ± 0.3 and 0.6 ± 0.3, respectively) (P = .019 and P = .013, respectively); there were no differences in all genes in ADF- and PRP-injected shoulders at 12 weeks (P > .05). Collagen continuity, orientation, and maturation of the tendon-to-bone interface were better in group C than in group D (P = .024, P = .012, and P = .013, respectively) at 12 weeks, and mean load to failure was 37.4 ± 6.2 N/kg and 24.4 ± 5.2 N/kg in group C and group D, respectively (P = .015). CONCLUSIONS: ADFs caused higher COL1 and BMP2 expression than PRP at 4 weeks and showed better histologic and biomechanical findings at 12 weeks after rotator cuff repair of the rabbit model. ADFs enhanced healing better than PRP in the rabbit model. CLINICAL RELEVANCE: This study could serve as a transitional study to show the effectiveness of ADFs in achieving tendon-to-bone healing after repair of chronic rotator cuff tears in humans.

Safety and Efficacy of Autologous Dermal Fibroblast Injection to Enhance Healing After Full-Thickness Rotator Cuff Repair: First-in-Human Pilot Study.

BACKGROUND: There is growing interest in various biological supplements to improve tendon healing in patients after arthroscopic rotator cuff repair. The ideal biological supplement to strengthen rotator cuff remains unknown. PURPOSE: To assess the safety and efficacy of autologous cultured dermal fibroblast (ADF) injection on tendon-to-bone healing in patients after arthroscopic rotator cuff repair. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Included were 6 patients who underwent arthroscopic rotator cuff repair between June 2018 and March 2020; all patients had a full-thickness rotator cuff tear (>2 cm) involving the supraspinatus and infraspinatus tendons. The patients were injected with ADF between the repaired tendon and footprint during arthroscopic rotator cuff repair using the suture bridge technique. The safety of ADFs and the procedure was evaluated at 5 weeks postoperatively, and the anatomical healing of the repaired tendon was accessed at 6 months postoperatively using magnetic resonance imaging and at 12 months using ultrasonography. Outcomes including shoulder range of motion (ROM), visual analog scale (VAS) for pain, and functional scores were measured at 6 and 12 months postoperatively. RESULTS: Adverse reactions to ADF injection were not observed at 6 months after surgery. VAS and functional scores at 6 and 12 months postoperatively were significantly improved compared with preoperative scores (all P < .05). However, there was no significant difference on any ROM variable between preoperative and postoperative measurements at 6 and 12 months (all P > .05). No healing failure was found at 6 and 12 months postoperatively. CONCLUSION: There was no adverse reaction to ADF injection, and all patients had successful healing after rotator cuff repair. A simple and easily accessible ADF injection may be a novel treatment option for increasing the healing capacity of torn rotator cuff tendons. Further clinical research is needed to verify the study results.

Optimal insertion site of glenoid baseplate in reverse total shoulder arthroplasty: anatomical simulation using three dimensional image processing software.

PURPOSE: Conventionally, the central structure of the baseplate is inserted through the point where the vertical and horizontal axes of the glenoid intersect (conventional insertion site (CIS)). However, there is scanty theoretical evidence that CIS has the optimal bone stock. We evaluated the optimal insertion site for the glenoid baseplate through the three-dimensional volumetric measurement of the glenoid bone stock. METHODS: Pre-operative computed tomography (CT) images of 30 consecutive reverse total shoulder arthroplasty procedures were analyzed. Three-dimensional image processing software was used to reconstruct CT and volumetrically measure the glenoid bone stock according to the simulated central peg. A simulated central peg was inserted to the medial pole of the scapula from 49 points determined along with the intersect point of the vertical and horizontal axes of the glenoid CIS at 2-mm intervals. The overlapped volume between the simulated central peg and glenoid vault, representing the amount of glenoid bone stock along the passage of the central peg, was then automatically calculated. RESULTS: The depth of the glenoid vault was 25.5 ± 3.0 mm (range, 19.3-31.5), and the mean overlapped volume between the simulated central peg and the glenoid vault was 623.0 ± 185.8 ml. The optimal insertion site for the bony purchase of the central peg was 2 mm inferior and posterior from the CIS (765.3 ± 157.5). CONCLUSION: The optimal insertion site of the baseplate is located slightly inferiorly and posteriorly to the CIS. This anatomical information may be used as a reference to determine the optimal insertion site of the baseplate according to an implant of a surgeon's choice.

Significance of the acromiohumeral distance on stress radiography for predicting healing and function after arthroscopic repair of massive rotator cuff tears.

BACKGROUND: A decreased acromiohumeral distance (AHD) is commonly detected in patients with massive rotator cuff tears (mRCTs). Most studies evaluating fixed humeral elevation have used preoperative or postoperative standardized radiography and not stress radiography. This study aimed to evaluate the predictive role of the preoperative AHD measured using stress radiography (AHD_stress) in rotator cuff healing and function after arthroscopic repair of mRCTs. METHODS: The data of 113 patients who underwent arthroscopic repair of mRCTs were analyzed. Postoperative cuff integrity was evaluated using magnetic resonance imaging at 1 year, and shoulder function was evaluated at a mean of 34.9 ± 17.8 months (range, 24-92 months) postoperatively. Forty-seven patients showed healing failure. Propensity score matching (1-1) was performed between the healed group and healing failure group. Thirty-eight patients in each group were matched in the final analysis. The AHD and AHD_stress were defined as the shortest distances from the inferior acromion to the superior humerus on standard anteroposterior radiography and stress radiography (5.4-kg weight applied inferiorly in a neutral position), respectively. The AHD difference (AHD_diff) was defined as the difference between the AHD and AHD_stress values. Receiver operating characteristic curve analysis was performed to determine cutoff values for significant variables. RESULTS: No difference in the mean preoperative AHD was found between the healed group (7.5 ± 2.0 mm) and healing failure group (6.9 ± 2.2 mm, P = .234). The AHD_diff value was significantly higher in the healed group (4.4 ± 2.1 mm) than in the healing failure group (3.0 ± 2.0 mm, P = .002; cutoff, 3.2 mm). Patients with an AHD_diff value ≥ 3.2 mm showed a lower healing failure rate (28.9% vs. 71.1%, P < .001) and higher functional scores than patients with an AHD_diff value < 3.2 mm. The AHD_diff value was higher in patients with an American Shoulder and Elbow Surgeons (ASES) score ≥ 80 (4.9 ± 1.9 mm) than in those with an ASES score < 80 (3.1 ± 2.1 mm, P = .024). Among patients with healing failure, only the postoperative AHD showed a significant difference between those with an ASES score ≥ 80 (7.0 ± 2.5 mm) and those with an ASES score < 80 (4.8 ± 2.1 mm, P = .009; cutoff, 4.8 mm). CONCLUSION: A reducible AHD, which increased by ≥ 3.2 mm under stress radiography, can be a favorable predictor of rotator cuff healing and function after arthroscopic repair of mRCTs. Our findings suggest that this new and simple radiologic parameter should be considered preoperatively and would be helpful to determine appropriate treatment strategies.

Risk factors for and prognosis of folded rotator cuff tears: a comparative study using propensity score matching.

BACKGROUND: The prognosis of rotator cuff repair (RCR) may be affected by the shape and quality of the torn rotator cuff tendon. However, only a few studies have reported on folded rotator cuff tears (FCTs). Therefore, this study aimed to evaluate the prognostic factors for FCT and clinical outcomes of FCT repair. METHODS: Through propensity score matching (PSM), 200 (40 patients with FCTs and 160 controls) of 1927 patients who underwent RCR from 2010 to 2016 were included. The variables not used for PSM were compared. The anatomic and functional outcomes were assessed at the final follow-up (32.3 ± 21.2 months), and the related prognostic factors for FCTs were evaluated. RESULTS: The risk factors for FCT were heel-type spur (odds ratio [OR], 11.6; P < .001) and delamination (OR, 2.3; P = .034). Although the functional scores at the final follow-up for both groups improved postoperatively and were not significantly different, the visual analog scale scores for pain (1.9 ± 2.1 vs. 1.2 ± 1.7, P = .034) and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) scores (83.1 ± 14.3 vs. 88.5 ± 12.2, P = .018) were significantly worse in the FCT group at 6 months postoperation. The retear rate was significantly higher in the FCT group (25.0 vs. 10.0%, P = .018). An FCT was a significant risk factor for retears (OR, 3.0; P = .015); however, a subgroup analysis revealed that the retear rate according to the management strategy for the folded portion (débridement of the folded portion vs. en masse repair including the folded portion) was not significantly different (26.7 vs. 24.0%, P > .99). CONCLUSION: The risk factors for FCTs were heel-type spur and delamination. The retear rate was significantly higher for patients with FCTs. An FCT was indicative of poor quality of the remaining tendon; therefore, FCT may be a prognostic factor for worse functional outcomes during the early postoperative period and poor healing potential.

New quantified measurement of fatty infiltration of the rotator cuff muscles using magnetic resonance imaging.

BACKGROUND: The degree of fatty infiltration of the rotator cuff muscle is typically evaluated using the Goutallier-Fuchs grading system, but its consistency remains controversial. This study aimed to evaluate a new quantified measurement of fatty infiltration based on three-dimensionally reconstructed volumetric data obtained from magnetic resonance images of non-pathologic shoulders using open-source software. METHODS: Fourteen shoulder 3-T magnetic resonance images (8 men, 6 women) without lesions obtained between 2010 and 2017 were analysed. Slicer version 4.6.2 was used to semi-automatically reconstruct the three-dimensional volumetric data from T2 sagittal oblique images and to differentiate fat tissue from rotator cuff muscle using the difference in signal intensity. RESULTS: The cutoff value for dividing muscle and fat was 508.9. The inter-class and intra-class correlations of each rotator cuff muscle and fat tissue were >0.9 (all P < 0.001). The mean muscle volume of the supraspinatus, infraspinatus, teres minor, and subscapularis were 15.2, 20.9, 13.3, and 29.7 mL, respectively. The muscle volume of the men was greater than that of the women (all P < 0.001), and the fat infiltration ratio was positively correlated with body mass index (all P < 0.05). CONCLUSIONS: The semi-automated quantified measurement of fatty infiltration of the rotator cuff muscles using magnetic resonance imaging and Slicer software presented excellent consistency. This technique could be an alternative measurement to complement the weak consistency of the Goutallier-Fuchs grading system. However, to reduce the error of measurement, this study evaluated non-pathologic shoulders. Therefore, further study using magnetic resonance imaging of pathologic shoulders is necessary for actual clinical application. LEVEL OF EVIDENCE: Level IV, case series, diagnostic study.

Comparing Clinical Outcomes After Subacromial Spacer Insertion Versus Other Reconstruction Methods in the Treatment of Irreparable Massive Rotator Cuff Tears.

BACKGROUND: Previous studies on subacromial spacer (SAS) insertion have been limited to case series that did not compare the effectiveness of this technique with other techniques. HYPOTHESIS: Outcomes after SAS insertion for the treatment of irreparable massive rotator cuff tears (IMRCTs) will be similar to those of other techniques. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: This retrospective study was based on data collected from patients who underwent correction of IMRCTs between January 2010 and October 2017. Group 1 patients (n = 17) received SAS insertion with or without partial repair; group 2 patients (n = 36) were treated with other techniques (isolated partial repairs or bridging grafts). Preoperative tear size and global fatty degeneration index values were evaluated. Range of motion, visual analog scale for pain, American Shoulder and Elbow Surgeons (ASES) score, Constant score, Simple Shoulder Test (SST), Disabilities of the Arm, Shoulder and Hand score, and acromiohumeral distance (AHD) were assessed preoperatively and at final follow-up at least 2 years after the surgery (range, 24-60 months). In both groups, ultrasonographic examination was performed at 3 and 6 months postoperatively, and magnetic resonance imaging (MRI) was performed at 1 year. RESULTS: Tear size and preoperative global fatty degeneration index were not significantly different between the groups (all P > .05). There were no differences in functional scores between the groups at final follow-up (all P > .05). AHD was maintained at final follow-up in group 1 (mean ± SD: 6.2 ± 2.1 mm [postoperatively] vs 6.7 ± 2.3 mm [final follow-up]; P = .678), and there was no difference compared with group 2 (7.2 ± 3.2 mm; P = .244). Patients with retears in group 2 (23 of 36, 63.9%) had lower ASES (P = .041) and SST (P = .027) scores at final follow-up when compared with patients in group 1. Six patients (35.3%) in group 1 had partial repairs; these patients had better external rotation at 90° (P = .047), better SST scores (P = .036), and higher AHDs at final follow-up (P = .046) than those in group 1 who had no repair. Three patients (50%) showed retears of partially repaired tendons on MRI. Of 13 patients (76.5%) in group 1 with postoperative MRI, 12 (92.3%) showed fibrotic tissue in the subacromial space not seen preoperatively. CONCLUSION: There was no difference in outcomes between SAS and the other reconstruction methods for treating IMRCTs. However, given the high retear rate associated with other techniques and poor functional outcomes after retear, SAS insertion could be a viable option for treating IMRCTs.