Arthroscopic assessment for lateral collateral ligament complex deficiency of the elbow: a cadaveric study.

PURPOSE: To evaluate whether elbow instability due to lateral collateral ligament complex injury can be assessed reliably through arthroscopy. METHODS: Eight fresh human cadaveric elbows were placed in a simulated lateral decubitus position. The radiocapitellar joint (RCJ) gap and ulnohumeral joint (UHJ) gap (mm) were measured with different sizes of probes from the posterolateral viewing portal. The elbow was 90 degrees flexed with neutral forearm rotation for RCJ gap measurement and 30 degrees flexed with full supination for UHJ gap measurement. Sequential testing was performed from Stage 0 to Stage 3 (Stage 0: intact; Stage 1: the release of the anterior 1/3 LCL complex; Stage 2: the release of the anterior two thirds of the LCL complex; and Stage 3: the release of the entire LCL complex) on each specimen. The mean gap of RCJ and lateral UHJ was used for the comparison between stages with the intact elbow. RESULTS: The mean RCJ gap distance in Stage 2 and Stage 3 was significantly increased compared to that in Stage 0 (Stage 0 vs. Stage 2: P = .008; Stage 0 vs. Stage 3: P = .010). The mean UHJ gap distance of Stage 1, Stage 2, and Stage 3 was significantly increased compared to that in Stage 0 (Stage 0 vs. Stage 1: P = 0.025; Stage 0 vs. Stage 2: P = .010; Stage 0 vs. Stage 3: P = .011). In contrast, the release of the anterior 1/3 of the LCL complex (Stage 1) was not significantly increased compared to the mean joint gap distance of RCJ (P = .157). CONCLUSION: Arthroscopic measurement of joint gap widening in RCJ and UHJ is a reliable assessment method to detect LCL complex deficiency that involves the anterior two thirds or more.

Anterior radial head subluxation in primary elbow osteoarthritis.

PURPOSE: To investigate elbows with primary osteoarthritis (OA) for the presence of anterior radial head subluxation. METHODS: A total of 71 patients with elbow osteoarthritis and 45 with lateral epicondylitis were initially identified. The baseline characteristics and preoperative elbow X-rays of consecutive patients that had been clinically confirmed with elbow OA or lateral epicondylitis between March 2011 and January 2020 were then retrospectively reviewed. The radiocapitellar ratio (RCR; the ratio of the displacement of the radial head about the diameter of the capitulum) was calculated using lateral views. These RCR values were compared between the OA and lateral epicondylitis cases. RESULT: A significant increase was detected in RCR values between patients in elbow OA and the control group (13.2% (± 10.6) vs -1.2% (± 6.8), P<0.001). Based on receiver operating characteristic curves, RCR values had an excellent area under the curve (0.89) for the detection of elbow OA (Youden index, 0.69; sensitivity, 89%; specificity, 80%). Based on the ROC curve, the cutoff value of RCR was 0.04. Patients with RCR ≥ 0.04 had a significantly higher proportion of cases with elbow OA (risk ratio, 31.50 [95% CI, 11.17-88.82]) than those with RCR ˂ 0.04 (P ˂ 0.001). CONCLUSION: Radial head subluxation is a radiographic finding associated with elbow OA and RCR ≥ 0.04 could be used as an aetiological factor for elbow OA diagnosis.

The role of the lateral part of the distal triceps and the anconeus in varus stability of the elbow: a biomechanical study.

BACKGROUND: The role of the lateral part of the distal triceps as a stabilizer in the lateral collateral ligament-deficient elbow and whether its effect in improving the stability is independent of that of the anconeus are unclear. METHODS: Seven cadaveric elbows were tested under gravity varus stress using a custom-made machine designed to simulate muscle loads while allowing passive flexion of the elbow. An injury model was created by sectioning the lateral collateral ligament and sparing the common extensor origin. The lateral part of the distal triceps tendon was loaded sequentially with 0 N, 10 N, 25 N, and 40 N. Each stage of the lateral part of the distal triceps loading was tested with the anconeus unloaded (inactive) or with a 25-N load applied (active). Articular contact pressures on the coronoid, the medial facet, and the lateral facet were collected and processed using Tekscan sensors and software. RESULTS: A significant decrease in the mean coronoid contact pressure was seen with sequential loading of the lateral part of the distal triceps (P < .001). The ratio of medial to lateral facet contact pressures significantly decreased with sequential loading of the lateral part of the distal triceps (P < .001), indicating a better distribution of the contact pressure between the medial and lateral facets as the lateral part of the distal triceps was loaded. These effects were statistically significant, both with and without anconeus loading. There was no significant modification of the effect of the lateral part of the distal triceps loading on the contact pressure by the anconeus loading (P = .47). However, with active anconeus loading, the contact pressure and the ratio of medial to lateral facet contact pressures were significantly lower for any stage of lateral triceps loading (P < .001), indicating a synergistic effect of the anconeus. CONCLUSIONS: In a lateral collateral ligament-deficient elbow, the lateral part of the distal triceps loading prevents the increased contact pressure on the coronoid under varus stress and improves the distribution of contact pressures on the coronoid. Anconeus loading further decreases and improves the distribution of the contact pressures; however, its effect is independent of that of the lateral part of the distal triceps. These results substantiate a role of the lateral part of the distal triceps as a dynamic constraint against elbow varus and have clinical implications for prevention and rehabilitation of elbow instability.

The role of the lateral collateral ligament-capsule complex of the elbow under gravity varus.

BACKGROUND: The lateral collateral ligament complex along with the capsule is likely to be at risk during arthroscopic extensor carpi radialis brevis release for lateral epicondylitis. We hypothesized that disruption of the lateral collateral ligament-capsule complex (LCL-cc) would increase the mean contact pressure on the coronoid under gravity varus. MATERIALS AND METHODS: Eight cadaveric elbows were tested via gravity varus and weighted varus (2 Nm) stress tests using a custom-made machine designed to simulate muscle loads while allowing passive flexion of the elbow. Mean articular surface contact pressure data were collected and processed using intra-articular thin-film sensors and software. Sequential testing was performed on each specimen from stage 0 to stage 3 (stage 0, intact; stage 1, release of anterior one-third of LCL-cc; stage 2; release of anterior two-thirds of LCL-cc; and stage 3, release of entire LCL-cc). The mean contact pressure on the coronoid and the mean ratio of contact pressure on the medial coronoid to that on the lateral coronoid (M/L ratio) were used for comparisons among the stages and the intact elbow. RESULTS: The overall mean contact pressure significantly increased in stage 2 (P = .0004 in gravity varus and P = .0001 in weighted varus) and stage 3 (P < .0001 in gravity varus and P < .0001 in weighted varus) compared with that in stage 0. In contrast, release of the anterior one-third of the LCL-cc (stage 1) did not significantly increase the mean contact pressure on the coronoid in any degree of flexion under gravity varus (P = .09) or weighted varus loading (P = .6). The M/L ratio difference between stage 0 and stage 1 was 1.1 ± 1.1 under gravity varus (P = .8) and 2.1 ± 1.0 under weighted varus (P = .2). The overall M/L ratios in stage 2 and stage 3 were significantly higher than those seen in stage 0 under gravity varus (P = .04 in stage 2 and P = .02 in stage 3) and weighted varus (P = .006 in stage 2 and P < .0001 in stage 3). CONCLUSIONS: Loss of the anterior two-thirds or more of the LCL-cc significantly increases the overall mean contact pressure on the coronoid, especially the medial coronoid, under both gravity varus and weighted varus. The LCL-cc also plays a role in the distribution of coronoid contact pressure against gravity varus loads.

Radiologically severe osteoarthritis is related to worse clinical outcomes after arthroscopic osteocapsular arthroplasty in primary elbow osteoarthritis at medium-term follow-up: a retrospective cohort study.

HYPOTHESIS: This study aimed to compare the clinical outcomes after arthroscopic osteocapsular arthroplasty (OCA) at medium-term follow-up according to the radiologic severity of primary elbow osteoarthritis (OA) and assess serial changes in clinical outcomes in each group. METHODS: Patients treated from January 2010 to April 2019 with arthroscopic OCA for primary elbow OA with a minimum of 3 years' follow-up were retrospectively assessed regarding range of motion (ROM), visual analog scale (VAS) pain score, and Mayo Elbow Performance Score (MEPS) preoperatively, at short-term follow-up (3-12 months postoperatively), and at medium-term follow-up (≥3 years after surgery). Preoperative computed tomography was performed to evaluate the radiologic severity of OA using the Kwak classification. Clinical outcomes were compared according to the radiologic severity of OA by their absolute values and the number of patients achieving the patient acceptable symptomatic state (PASS). Serial changes in the clinical outcomes in each subgroup were also assessed. RESULTS: Of the 43 patients, 14, 18, and 11 were classified as the stage I, II, and III groups, respectively; the mean follow-up duration was 71.3 ± 28.9 months, and the mean age was 56.5 ± 7.2 years. At medium-term follow-up, the stage I group had a better ROM arc (stage I, 114° ± 14°; stage II, 100° ± 23°; and stage III, 97° ± 20°; P = .067) and VAS pain score (stage I, 0.9 ± 1.3; stage II, 1.8 ± 2.1; and stage III, 2.4 ± 2.1; P = .168) than the stage II and III groups without reaching statistical significance, whereas the stage I group had a significantly better MEPS (stage I, 93.2 ± 7.5; stage II, 84.7 ± 11.9; and stage III, 78.6 ± 15.2; P = .017) than the stage III group. The percentages of patients achieving the PASS for the ROM arc (P = .684) and VAS pain score (P = .398) were comparable between the 3 groups; however, the percentage achieving the PASS for the MEPS was significantly higher in the stage I group than in the stage III group (100.0% vs. 54.5%, P = .016). During serial assessment, all clinical outcomes tended to improve at the short-term follow-up. Compared with the short-term period, the ROM arc tended to decrease at the medium-term follow-up whereas the VAS pain score and MEPS overall did not show significant changes. CONCLUSION: After arthroscopic OCA, the stage I group showed an overall better ROM arc and pain score than the stage II and III groups at medium-term follow-up, whereas the stage I group showed a significantly better MEPS and higher percentage of patients achieving the PASS for the MEPS than the stage III group.

Biomechanical impact of elbow motion in elbow stiffness.

BACKGROUND: A mechanical block in the elbow due to osteophytes in the olecranon fossa is a common clinical symptom for elbow stiffness. PURPOSE/HYPOTHESIS: This study aims to understand the biomechanical characteristics or changes in the stiff elbow in the resting (or neutral) and swing position of the arm using a cadaveric model. The hypotheses included the following: (1) a difference exists in the articular contact pressure of the elbow by comparing the non-stiff and stiff models in in vivo studies; (2) the degree of stiffness would affect the increase of the joint loading of the elbow. STUDY DESIGN: Controlled laboratory study, cadaveric study. METHODS: Eight fresh-frozen specimens from individuals of both sexes were included in the biomechanical study. The specimen was mounted on a custom-designed jig system with gravity-assisted muscle contracture to mimic the elbow in a standing position. The elbow was tested in two conditions (the resting and passive swing). Contact pressure was recorded for three seconds in the resting position, which was the neutral position of the humerus. By dropping the forearm from 90° of the elbow flexion, the passive swing was performed. The specimens were tested sequentially in three stages of stiffness (stage 0, no stiffness; stage 1, 30° of extension limitation; and stage 2, 60° of extension limitation). After data collection was completed in stage 0, a stiff model was sequentially created for each stage. The stiff model of the elbow was created by blocking the olecranon by inserting a 2.0 K-wire into the olecranon fossa horizontally with the intercondylar axis. RESULTS: The mean contact pressures were 279 ± 23, 302 ± 6, and 349 ± 23 kPa in stages 0, 1, and 2, respectively. The increases in the mean contact pressure in stages 2 versus 0 were significant (P < 0.0001). The mean contact pressures were 297 ± 19, 310 ± 14, and 326 ± 13 kPa in stages 0, 1, and 2, respectively. The peak contact pressures were 420 ± 54, 448 ± 84, and 500 ± 67 kPa in stages 0, 1, and 2, respectively. The increases in mean contact pressure in stage 2 versus 0 were significant (P = 0.039). The increases in peak contact pressure in stages 0 versus 2 were significant (P = 0.007). CONCLUSIONS: The elbow bears the load created by gravity and muscle contracture in the resting and swing motion. Moreover, extension limitation of stiff elbow increases the load bearing in the resting position and swing motion. Careful surgical management should be considered for meticulous clearance of bony spur around olecranon fossa to resolve the extension limitation of the elbow.

Return to physical activities after arthroscopic rotator cuff repair: a systematic review and meta-analysis.

BACKGROUND: Rotator cuff tear is one of the most common disorders in orthopedic surgery. When conservative treatment fails, arthroscopic rotator cuff repair has become the most common procedure to achieve a functional shoulder. HYPOTHESIS/PURPOSE: The articles on return to activities following arthroscopic rotator cuff repair have not been collectively analyzed and investigated. We aimed to review systematically and perform a meta-analysis of studies on the return to activities which consist of the return to work, return to sports, and return to daily activities following arthroscopic rotator cuff repair. STUDY DESIGN: Systematic Review and Meta-Analysis. METHODS: Articles regarding return to activities were systematically searched using databases of PubMed, MEDLINE via EBSCO, ScienceDirect, and ProQuest. The review was done according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Guideline. The study protocol was registered in the PROSPERO International Prospective Register of Systematic Reviews. Studies with a level of evidence 1-4 that examined the rate of return to activities after arthroscopic rotator cuff repair were included and analyzed. RESULTS: Fifteen studies published between 2005 and 2021 were included, with 1065 patients (644 male and 421 female). The patient populations are workers and athletes. The meta-analysis on the combined effect of a return to activities using the random-effects model was 88.5% (83.8% on return to work, 88.2% on return to sport, and 97.3% on return to daily activities). The mean duration for return to activities is 6.59 months. CONCLUSION: As much as 88.5% of patients were able to return to activities after arthroscopic rotator cuff repair with a mean duration of 6.59 months. Preoperative factors (gender, workload, chronicity, tear size, and cholesterol level) may contribute to the rate and duration of return to activities.

Patient-specific instrumentation improves the reproducibility of preoperative planning for the positioning of baseplate components with reverse total shoulder arthroplasty: a comparative clinical study in 39 patients.

BACKGROUND: The application of patient-specific instrumentation (PSI) for reverse total shoulder replacement has been rapidly increasing, which could reduce errors in implant positioning. Although PSI theoretically holds promise, evidence of the accuracy and reliability of PSI in shoulder replacement surgery is limited. METHODS: Thirty-nine shoulders that underwent reverse total shoulder arthroplasty were included in this study and categorized into two groups: the conventional (n = 20) and PSI (n = 19) groups. Screw (length and angle) and baseplate (version, inclination, translation, and rotation) positioning were calculated based on postoperative computed tomography images using a three-dimensional measurement tool. The difference between the values of the preoperative target and postoperative measurement was calculated to evaluate the reproducibility of preoperative planning. Screw involvement in the suprascapular and spinoglenoid notches was assessed. Thus, the correlation between the position of the baseplate and the screws was assessed. RESULTS: The mean differences between the planned length and angle (anteroposterior and superoinferior angles) and postoperative measurement in the PSI group were significantly smaller than those in the conventional group. Similarly, the mean difference in baseplate rotation between the planned and postoperative measurements in the PSI group was significantly lower than that in the conventional group (4.5° vs 10.6°; P < .001). The spinoglenoid notch was involved in 10 cases in the conventional group and 2 cases in the PSI group, and this difference was significant (P = .014). Overall, the mean difference between the preoperative and postoperative version, inferior inclination, and rotation values for the baseplate position was significantly correlated with the values for screw position (length and angle). CONCLUSIONS: PSI improves the reproducibility of preoperative planning for baseplate and screw positioning and reduces the risk of neurovascular injury in reverse total shoulder arthroplasty.

Radial Head Prosthetic Replacement in Adolescents: A Report of 5 Cases.

BACKGROUND: The management of severe radiocapitellar joint pathologies in young patients is challenging. Radial head arthroplasty (RHA) is a treatment option in the adult population, but most surgeons avoid implementing it in younger patients, and there are no published results for patients younger than 16 years. METHODS: Our retrospective cohort describes 5 patients (4 male 1 female) who underwent cementless modular RHA at an average age of 14 years (range: 13 to 15). The preoperative diagnoses were post-traumatic radiocapitellar incongruity and arthrosis because of previous Salter-Harris type 3 or 4 fractures of the radial head in 3 cases; and axial instability of the forearm following failed radial head excision in 2 cases. Because of the complexity of the elbow pathology in these cases, all underwent concomitant procedures including: contracture release (5 cases), corrective ulnar osteotomy (2 cases), distal ulnar shortening osteotomy, excision of radioulnar synostosis, microfracture of the capitellum, and partial excision of the medial triceps (1 case each). Collected data included patient-reported outcomes, visual analog scale pain score at rest and during physical activity and radiographic assessment of arthritis and prosthesis loosening. RESULTS: Average clinical follow-up was 8 years (range: 3 to 13). All 5 patients were pain-free at rest, and 3 reported moderate elbow pain (visual analog scale: 5 to 6) with physical activity. At an average radiographic follow-up of 3 years (range: 0.5 to 5), 3 patients showed mild progression of elbow arthrosis, but there were no signs of progressive capitellar erosion or implant loosening. Only 1 complication was noted-development of heterotopic ossification in 1 patient, which required open heterotopic ossification excision and contracture release 2 years following the RHA. None of the patients required prosthesis revision or removal. CONCLUSION: RHA was successful in improving pain and axial forearm stability in this very small series of adolescent patients. Concerns regarding long-term longevity and complications still exist. Considering the lack of other reliable treatment options, RHA may be indicated in this challenging patient population. LEVEL OF EVIDENCE: Level IV: therapeutic study-case series.

Forearm Interosseous Ligaments: Anatomical and Histological Analysis of the Proximal, Central, and Distal Bands.

PURPOSE: To characterize and compare the histological structure of the proximal, central, and distal bands of the interosseous membrane (IOM) of the human forearm in fresh-frozen specimens. METHODS: The IOMs from 16 fresh-frozen left forearm specimens were carefully dissected and examined. The footprint areas of the proximal, central, and distal IOM bands were measured in 6 specimens. The histological characteristics of the IOM bands were evaluated using hematoxylin-eosin and Masson trichrome staining protocols in 10 specimens as histological analysis necessitated an intact footprint. The footprint areas of the IOM were measured using an image processing program. The insertion complex was assessed using a light microscope. RESULTS: Histological assessment revealed that the IOM structure demonstrated similarities with ligament structure. The average footprint areas of the proximal, central, and distal bands at the radial site were 11.1 ± 0.8, 180.4 ± 30.4, and 10.7 ± 1.3 mm2, respectively. At the ulnar site, they were 11.0 ± 1.1, 171.8 ± 30.1, and 10.7 ± 1.2 mm2, respectively. The insertion complex of the IOM into the bone comprised 4 layers: (1) interwoven collagen, (2) oblique collagen, (3) mineralized fibrocartilage (tidemark), and (4) lamellar bone. The average tidemark zone thicknesses of the proximal, central, and distal bands were 20.1 ± 6.3, 107.8 ± 22.9, and 20.6 ± 4.7 µm, respectively at the radial site and 12.0 ± 4.5, 85.7 ± 23.2, and 13.5 ± 6.9 µm, respectively at the ulnar site. CONCLUSIONS: In this study, we confirm that the histological characteristics of the IOM are similar to those of ligaments. Compared with the proximal and distal bands, the central band has a greater footprint area and thicker tidemark zone. CLINICAL RELEVANCE: If surgical reconstruction is performed, the size and histological characteristics of the graft should be similar to those of the native ligaments.

Subacromial bursal preservation can enhance rotator cuff tendon regeneration: a comparative rat supraspinatus tendon defect model study.

BACKGROUND: The role of subacromial bursa in rotator cuff surgery is unknown. This study aimed to assess the subacromial bursa's role in the healing of supraspinatus tendon injury in a rat model. METHODS: Twenty-three male Sprague-Dawley rats (9 weeks old; weight, approximately 296 g) were used in this study. Three rats used as biomechanical study controls were killed at 12 weeks of age. A supraspinatus tendon defect was made bilaterally in 20 rats, whereas an additional subacromial bursa sectioning was performed on the left side. Six rats were killed for biomechanical testing and 4 were killed for histologic observation at 3 and 9 weeks, respectively. RESULTS: The regenerated tendon in the bursal preservation group showed significantly superior biomechanical properties in maximum load to failure at 3 and 9 weeks and stiffness at 9 weeks after surgery compared with the bursal removal group. The modified Bonar scale scores showed better regenerated supraspinatus tendons in the bursal preservation group. CONCLUSION: The present study found that the subacromial bursa plays an important role in rotator cuff regeneration in this rat supraspinatus injury model. Extensive bursectomy of the subacromial bursa may not be recommended in rotator cuff repair surgery, though future in vivo human studies are needed to confirm these observations.

The contact area of the radiocapitellar joint under pronation and supination with axial load using a 3-dimensional computed tomography: an in vivo study.

OBJECTIVE: To evaluate the contact area of the radiocapitellar joint with forearm pronation and supination under axial loading. MATERIALS AND METHODS: Six healthy volunteers (2 males and 4 females, mean age: 44.6 years) were included in the study. A computed tomography scan of the extended elbow joints was obtained at 4 positions of forearm: full pronation with or without load and full supination with or without load. Mimics, 3-matic Medical, Geomagic, and Photoshop were used to reconstruct 3-dimensional models. The contact area of the radiocapitellar joint was measured. Shifting of the center of the contact area of the radiocapitellar joint was measured. RESULTS: The axial load added 8.6% and 10.5% contact area to pronation and supination without load, respectively. From pronation without load, the center of contact area significantly shifted 2.4 ± 1.1 mm anteromedially to supination without load and shifted by 1.0 ± 0.5 mm to the center of the radial head compared with the pronation with load. The center of the contact area significantly shifted 2.4 ± 1.5 mm anteromedially from the pronation to the supination under loading. The contact area of the tuberosity anterior in the radial head significantly increased by 14% (without load) and 8% (with load) from pronation to supination. CONCLUSION: Axial loading increases the contact area of the radiocapitellar joint. The center of the contact area of the radiocapitellar joint changed according to loading and shifted to the anterior tuberosity of the radial head from forearm pronation to supination.

Determination of the patient acceptable symptomatic state after osteocapsular arthroplasty for primary elbow osteoarthritis.

BACKGROUND: The study aimed (1) to determine patient acceptable symptomatic state (PASS) values for the pain visual analog scale (PVAS), range-of-motion (ROM) scale difference, Mayo Elbow Performance Score (MEPS), and Self-evaluation Elbow (SEE) following osteocapsular arthroplasty for primary elbow osteoarthritis and (2) to determine factors for achieving the PASS. METHODS: The study analyzed retrospectively collected osteocapsular arthroplasty registry data from January 2010 to April 2019. Fifty patients were evaluated, and anchor questions for deriving PASS values were administered at a 1-year follow-up. PASS values for the PVAS score, ROM difference, MEPS, and SEE score were derived using a sensitivity- and specificity-based approach. Univariate and multivariate logistic regression analyses were performed to determine factors for achieving the PASS. A subgroup comparison analysis based on age was also conducted. RESULTS: The PASS value was 1.0 for the PVAS score, 15° for ROM difference, 75 for the MEPS, and 60 for the SEE score. Older age (≥65 years) showed significantly lower odds ratios for achieving the PASS for the PVAS score (0.888; 95% confidence interval, 0.804-0.981; P = .032) and ROM (0.861; 95% confidence interval, 0.760-0.976; P = .020). CONCLUSION: Reliable PASS values were derived for the PVAS score, ROM difference, MEPS, and SEE score after osteocapsular arthroplasty. The PASS values defined in this study can be implemented as clinically relevant targets in patients undergoing osteocapsular arthroplasty. An analysis of factors that affect clinical symptom improvement showed that older age (≥65 years) was significantly correlated with lower PASS values for the PVAS score and ROM.

Topography of sensory receptors within the human glenohumeral joint capsule.

BACKGROUND AND HYPOTHESES: Sensory receptors in the joint capsule are critical for maintaining joint stability. However, the distribution of sensory receptors in the glenohumeral joint of the shoulder, including mechanoreceptors and free nerve endings, has not been described yet. This study aimed to describe the distributions of different sensory receptor subtypes in the glenohumeral joint capsule. Our hypotheses were as follows: (1) Sensory receptor subtypes would differ in density but follow a similar distribution pattern, and (2) the anterior capsule would have the highest density of sensory receptors. METHODS: Six glenohumeral joint capsules were harvested from the glenoid to the humeral attachment. The capsule was divided into 4 regions of interest (anterior, posterior, superior, and inferior) and analyzed using modified gold chloride stain. Sensory receptors as well as free nerve endings were identified and counted under a light microscope from sections of each region of interest. The density of each sensory receptor subtype was calculated relative to capsule volume. RESULTS: Sensory receptors were distributed in the glenohumeral joint capsule with free nerve endings. The anterior capsule exhibited the highest median density of all 4 sensory receptors examined, followed by the superior, inferior, and posterior capsules. The median densities of these sensory receptor subtypes also significantly differed (P = .007), with type I (Ruffini corpuscles) receptors having the highest density (2.97 U/cm3), followed by type IV (free nerve endings, 2.25 U/cm3), type II (Pacinian corpuscles, 1.40 U/cm3), and type III (Golgi corpuscles, 0.24 U/cm3) receptors. CONCLUSION: Sensory receptor subtypes are differentially expressed in the glenohumeral joint capsule, primarily type I and IV sensory receptors. The expression of sensory receptors was dominant in the anterior capsule, stressing the important role of proprioception feedback for joint stability. The surgical procedure for shoulder instability should consider the topography of sensory receptors to preserve or restore the proprioception of the shoulder joint.

The elbow plica: a systematic review of terminology and characteristics.

BACKGROUND: There has been a lack of evidence regarding the structure of the elbow plica, or synovial fold. Inconsistency remains regarding the correct terminology, prevalence, and investigation used to understand this anatomic structure. METHODS: For this systematic review, we searched the PubMed, Ovid-MEDLINE, Cochrane, Google Scholar, and Embase databases using keywords as well as medical subject headings for English-language studies. We conducted a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. RESULTS: We included 27 articles in this review. "Plica" was the most commonly used terminology (33%). The prevalence of plicae in asymptomatic and symptomatic patients was 77% and 97%, respectively. Provocative factors were sporting activities (57%), including those performed by professional athletes, and heavy labor (43%). Lateral elbow pain represented the most common symptom (49%). Magnetic resonance imaging was the most commonly used diagnostic modality (64%). On the magnetic resonance imaging scans of symptomatic patients, the most common location of the plica was the posterolateral region (54%) and its thickness was a minimum of 3 mm. In 2 studies that included symptomatic patients, the plica was found to cover more than one-third of the radial head. CONCLUSION: Plicae are prevalent in both asymptomatic and symptomatic patients. Consideration of the pathologies associated with an elbow plica helped identify the following: (1) its thickness is >3 mm and (2) its location is in the posterolateral aspect and/or it covers more than one-third of the radial head quadrant.

Remnant Tendon Preservation Enhances Rotator Cuff Healing: Remnant Preserving Versus Removal in a Rabbit Model.

PURPOSE: To assess whether anatomic repair preserving remnant tendon tissue can enhance tendon-to-bone healing biomechanically and histologically in a rabbit rotator cuff tear model. METHODS: In this controlled laboratory study, bilateral infraspinatus tenotomy from the greater tuberosity, with remnant tendon on the footprint, was performed in 26 New Zealand white rabbits. An open transosseous technique was used to perform bilateral infraspinatus tendon repair 1 week later. Preservation and removal of the remaining tendon were performed on the left and right sides, respectively. Seven rabbits each were killed humanely for biomechanical testing and 6 rabbits each were killed humanely for histologic evaluation at 4 and 12 weeks. RESULTS: Significantly superior biomechanical properties were shown in the remnant tissue-preservation group at 4 and 12 weeks in terms of maximum load (89.6 ± 24.3 N vs 68.2 ± 20.7 N at 4 weeks, P = .048; 120.8 ± 27.5 N vs 93.3 ± 25.1 N at 12 weeks, P = .035) and stiffness (25.3 ± 3.4 N/mm vs 17.7 ± 5.2 N/mm at 4 weeks, P = .009; 26.7 ± 5.2 N/mm vs 19.4 ± 5.2 N/mm at 12 weeks, P < .001). Improved bone-tendon interface histologic maturity scores (14.8 ± 0.9 vs 8.2 ± 1.5 at 4 weeks, P = .027; 16.8 ± 0.7 vs 10.5 ± 1.4 at 12 weeks, P = .027) and large metachromasia areas (0.117 ± 0.053 mm2 vs 0.032 ± 0.017 mm2 at 4 weeks, P = .022; 0.14 ± 0.046 mm2 vs 0.037 ± 0.016 mm2 at 12 weeks, P = .007) were obtained in the preservation group compared with the removal group at 4 and 12 weeks. CONCLUSIONS: This study showed that preserving remnant tissue in anatomic repair can significantly improve rotator cuff healing compared with remnant tissue removal on the footprint in terms of biomechanical properties, bone-tendon interface histologic maturity scores, and metachromasia at 4 and 12 weeks after repair in a rabbit rotator cuff tear model. CLINICAL RELEVANCE: The results suggest that preservation of remnant tissue on the footprint containing the native bone-tendon interface, when present, may be a better option for rotator cuff healing in rotator cuff repair surgery.

Arthroscopic osteocapsular arthroplasty for advanced-stage primary osteoarthritis of the elbow using a computed tomography-based classification.

HYPOTHESIS: Arthroscopic osteocapsular arthroplasty for stage III osteoarthritis (advanced stage) shows worse clinical and radiologic outcomes compared with stage I or II according to computed tomography (CT)-based classification. METHODS: Clinical and radiologic outcomes in 65 patients treated with arthroscopic osteocapsular arthroplasty were retrospectively analyzed for range of motion (ROM) arc, functional score (Mayo Elbow Performance Score [MEPS]), and pain score (visual analog scale [VAS]). Patients were classified into stage I or II (n = 44) and stage III (n = 21) groups according to CT-based classification, and postoperative clinical outcomes and complications were analyzed. RESULTS: Mean follow-up duration was 32.9 ± 13.7 months (range, 24-69). The average patient age was 52 ± 10 years (range, 40-63). Improvements from preoperative to final follow-up were seen in the overall ROM-flexion from 94° ± 19° to 129° ± 14° (P < .01), ROM-extension from 25° ± 12° to 14° ± 7° (P < .01), MEPS from 45 ± 13 to 78 ± 14 (P < .01), and VAS score from 6.3 ± 1.6 to 3.1 ± 1.4 (P < .01). Subgroup analysis using the CT-based classification revealed that stage III led to worsened VAS score and MEPS than stage I or II. CONCLUSIONS: Arthroscopic osteocapsular arthroplasty can be recommended for its favorable overall treatment outcomes for elbow osteoarthritis. However, stage III shows worse clinical and radiologic outcomes compared with stage I or II according to CT-based classification.

Motion quality in rotator cuff tear using an inertial measurement unit: new parameters for dynamic motion assessment.

PURPOSE: This study aimed to (1) figure out the difference in motion smoothness between a nonpathologic shoulder and the other with a rotator cuff tear by measuring the angular velocity using an inertial measurement unit (IMU) sensor and (2) propose the parameters to describe the difference because there is no literature on this topic. MATERIAL AND METHODS: We enrolled patients with rotator cuff disease diagnosed by magnetic resonance imaging. The intact shoulder of participants was compared with the shoulder with rotator cuff tear by using IMU on the basis of the parameters that establish motion smoothness: the number of peaks, the peak velocity-to-mean velocity ratio (PV/MV), and the number of sign reversals. In addition, subgroup analysis was performed with respect to tear size (small to medium vs. large to massive). In addition, correlations with the American Shoulder and Elbow Surgeons score and symptom duration (months) were evaluated. RESULTS: Among 24 patients (15 males, 9 females), all 3 parameters for the motion quality of patients with a rotator cuff tear exhibited significant difference. The parameters showed a significant difference between the small to medium tear group and the large to massive tear group. A negative correlation was found between symptom duration and parameters of motion quality, except for PV/MV. CONCLUSIONS: Motion quality assessment using IMU showed a marked difference in the shoulder with a rotator cuff tear compared with the intact shoulder. Hence, IMU-based parameters for dynamic motion quality could be considered as an option for assessing the function of the shoulder.

Suprascapular nerve neuropathy leads to supraspinatus tendon degeneration.

BACKGROUND: Nowadays most of attention regarding rotator cuff is payed to how to reduce the failure after rotator cuff surgical repair rather than how to prevent the rotator cuff tear before surgery. The etiologies of rotator cuff tear are still unclear. As we all know, the nerve system include brain, spinal cord, sensory organs and all the neurons allover our body coordinates the homoeostasis of our body. We hypothesis that the nerve injury proximal to suprascapular nerve can leads to rotator cuff degeneration even tear. METHODS: Thirty-six SD rats were used. A defect on the suprascapular nerve was made on the right side and a sham surgery on the nerve (expose nerve only) at the left side. The insertion of supraspinatus tendon and supraspinatus muscle were harvested for testing. Twelve rats were sacrificed for biomechanical (six rats) and histological (six rats) properties were evaluated at 3, 6, and 9 weeks after surgery, respectively. RESULTS: Significant inferior biomechanical properties of rotator cuff were found in nerve injured side compared to the nerve intact side at 6-9 weeks. Significant muscle atrophy was found at nerve injured side from 3 to 9 weeks. The enthesis of nerve injured side showed significant excessive cell maturity, reduced cellularity, smaller metachromasia area and more type-III collagen especially at 9 weeks after surgery. CONCLUSIONS: The neuropathy proximal to suprascapular nerve can leads to rotator cuff degeneration even tear. The nerve dysfunction maybe an important etiology for rotator cuff tear.

Navigation-assisted suture anchor insertion for arthroscopic rotator cuff repair.

BACKGROUND: Suture anchor placement for subscapularis repair is challenging. Determining the exact location and optimum angle relative to the subscapularis tendon direction is difficult because of the mismatch between a distorted arthroscopic view and the actual anatomy of the footprint. This study aimed to compare the reliability and reproducibility of the navigation-assisted anchoring technique with conventional arthroscopic anchor fixation. METHODS: Arthroscopic shoulder models were tested by five surgeons. The conventional and navigation-assisted methods of suture anchoring in the subscapularis footprint on the humeral head were tested by each surgeon seven times. Angular results and anchor locations were measured and compared using the Wilcoxon signed rank test. Interobserver intraclass correlation coefficients (ICCs) were analyzed among the surgeons. RESULTS: The mean angular errors of the targeted anchor fixation guide without and with navigation were 17° and 2° (p < 0.05), respectively, and the translational errors were 15 and 3 mm (p < 0.05), respectively. All participants showed a narrow range of anchor fixation angular and translational errors from the original target. Among the surgeons, the interobserver reliabilities of angular errors for ICCs of the navigation-assisted and conventional methods were 0.897 and 0.586, respectively, and the interobserver ICC reliabilities for translational error were 0.938 and 0.619, respectively. CONCLUSIONS: The navigation system may help surgeons be more aware of the surrounding anatomy and location, providing better guidance for anchor orientation, including footprint location and anchor angle.