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The future development of advanced molecular systems with controlled rotation requires the development of an effective methodology for assessing the rotational performance of artificial machine components. We identified two patterns of the dielectric behavior for polar rotators in a static non-polar framework of sizable crystal showing relations between the spectral and molecular-level features of solid-state rotary motion. Various functionalization of phenylene rotors with a fluorine atom(s) changed rotational performance from high to low with rotational barriers ranging from 6.06 to 11.84 kcal mol-1. The meta-F-substitution favored rotator-rotator contacts allowing for the implementation of fast rotary motion. Contrary, the presence of rotator-stator contacts inhibited independent rotator dynamics leading to opposite spectral behavior in terms of temperature evolution of loss peak amplitude. Our observations, supported by an analysis based on an asymmetric double well-potential model, show that easily noticeable spectral differences encoded some molecular-level information important for the implementation of rotary motion.

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PURPOSE: This study aimed to identify the demographic-, radiographic-, and surgery-related factors influencing postoperative functional internal rotation (fIR) following reverse total shoulder arthroplasty (RTSA). METHODS: In this retrospective cohort study, patients who underwent RTSA between June 2013 and April 2018 at a single institution were assigned to two groups ("IROgood" or "IRObad"). Patients were classified as having good fIR (≥8 points in the Constant-Murley score (CS) and fIR to the twelfth thoracic vertebra or higher) or poor fIR (≤2 points in the CS and fIR to the twelfth thoracic vertebra or lower) after RTSA with a single implant model. The minimum follow-up period was two years. Standardized shoulder-specific scores (Visual Analogue Scale (VAS), Simple Shoulder Test (SST), American Shoulder and Elbow Surgeons Score (ASES), Constant-Murley score (CS)) were used to assess the pre- and postoperative functional status of patients. Postoperative radiographic evaluation included the distalization shoulder angle (DSA), lateralization shoulder angle (LSA), critical shoulder angle (CSA), acromiohumeral distance (AHD), glenoid inclination (GI), medialization of the center of rotation (COR), lateralization of the humerus, and distalization of the greater tuberosity. Additionally, preoperative evaluation included rotator cuff arthropathy according to Hamada, glenoid version, anterior or posterior humeral head subluxation, and fatty infiltration of the rotator cuff according to Goutallier. Univariate analysis of demographic, surgical, radiographic, and implant-associated parameters was performed to identify factors associated with postoperative fIR. The Shapiro-Wilk test assessed the normal distribution of the data. Intergroup comparisons regarding demographic and surgery-related factors were conducted using the Mann-Whitney-U Test. Radiographic changes were compared using chi-square or Fisher's exact tests. The significance level was set at p < 0.05. RESULTS: Of a total of 42 patients, 17 (age: 73.7 ± 5.0 years, follow-up (FU) 38 months [IQR 29.5-57.5]) were included in the "IRObad" group, and 25 (age: 72 ± 6.1 years, FU 47 months [IQR 30.5-65.5]) were included in the "IROgood" group. All patients were treated with the same type of implant (glenosphere size: 36 mm, 14.3%; 39 mm, 38.1%; 42 mm, 47.6%; neck-shaft angle: 135° in 68.0%; 155° in 32.0%) and had comparable indications. Univariate analysis did not reveal any of the investigated demographic, radiographic, or surgery-related parameters as risk factors for poor postoperative fIR (p > 0.05). CONCLUSION: None of the investigated factors, including implant-associated parameters, influenced postoperative fIR after RTSA in this cohort.

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BACKGROUND: No comprehensive study has been conducted on the effects of high tibial osteotomy (HTO) on the coronal, sagittal, and axial alignments of the ankle joint. Therefore, this study aimed to investigate the multiplane changes in the ankle joint following HTO using the EOS biplanar X-ray imaging system. METHODS: The medical records of 43 patients who underwent HTO for the treatment of medial knee osteoarthritis were retrospectively reviewed. Preoperative and postoperative EOS images and lower-extremity scanograms were evaluated; the correlations between the outcomes were evaluated. RESULTS: After HTO, the ankle joint axis point on the weight-bearing line showed significant lateralization (p < .001). The knee lateral ankle surface angle increased significantly in the sagittal alignment (p < .001). The distal tibia showed a significant internal rotation in the axial plane (p = .022). Tibial rotation showed no significant relationship with the other parameters. CONCLUSIONS: HTO induced lateralization of the ankle joint axis (coronal), increased the posterior tibial slope (sagittal), and caused the internal rotation of the distal tibia (axial). Axial changes in the distal tibia showed no significant relationship with other coronal and sagittal parameters of the ankle joint. We suggest that surgeons should consider, during HTO, that the ankle joint axis shifts laterally and distal tibia has tendency to rotate internally after HTO.

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Objectives: Reverse total shoulder arthroplasty (rTSA) has shown success in the treatment of end-stage glenohumeral pathology. However, one major shortcoming has been the lack of internal rotation (IR), which can have significant functional consequences. Much research has been conducted to maximize IR after rTSA, but the literature is unclear which measurement of IR represents the "gold standard" between vertebral level and goniometer-based measurements. Methods: Patients were prospectively enrolled into one of three groups: postoperative from rTSA, subacromial pain (SA), and normal. IR measurements were obtained either by the vertebral body level, by which radiographic markers indicated the highest level that the patient was able to reach on the body midline; or by using a goniometer while the shoulder was in 90-degree abduction as the patient stood upright. Results: Comparisons between the radiographic vertebral level and goniometer IR measurements showed significant correlations within the normal (r = - 0.43, P = 0.02) and SA pain groups (r = - 0.44, P = 0.02). The rTSA group did not quite reach statistical significance (P = 0.11), but had a moderate correlation coefficient (r = - 0.33). Accuracy of visual IR measurements was also significant. All rTSA group vertebral level measurements were within two vertebral levels, while only 84.6% of IR measurements by goniometer were within 15 degrees. Visual vertebral level measurements were found to be more accurate for the SA pain group (86.2 vs 66.7%). Conclusion: A comparison of the two primary IR measurement methods for shoulders was shown to have a correlation. This would allow for direct comparison of different literature using only one measurement method. While the correlation is not yet strong enough to allow for conversion between the two measurement types, creating a matched cohort taking into account other factors may lead to the correlation reaching this point.

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The rotational spectra of the 1:1 complex formed by acrolein and methanol and its deuterated isotopologues have been analyzed. Two stable conformations in which two hydrogen bonds between the two moieties are formed were detected. The rotational lines show a hyperfine structure due to the methyl group internal rotation in the complex and the V3 barriers hindering the motion were determined as 2.629(5) kJ mol-1 and 2.722(5) kJ mol-1 for the two conformations, respectively. Quantum mechanical calculations at the MP2/aug-cc-pVTZ level and comprehensive analysis of the intermolecular interactions, utilizing NCI and SAPT approaches, highlight the driving forces of the interactions and allow the determination of the binding energies of complex formation.

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Acetone (CH3COCH3), the simplest ketone, has recently attracted considerable attention for its important role in atmospheric chemistry and in the formation of ices in extraterrestrial sources that contain complex organic molecules. In this study, we employed a combination of experimental rotational spectroscopy and quantum chemistry calculations to investigate the structure and dynamics of the acetone-water complex. Our aim was to understand how non-covalent interactions with water affect the methyl internal rotation dynamics of acetone, and how water-centered large amplitude motions alter the observed physical properties compared to those predicted at the equilibrium position. Detailed rotation-tunneling analyses of acetone-H2O and -D2O reveal that the interactions with water disrupt the equivalence of the two methyl rotors, resulting in a noticeably lower methyl rotor barrier for the top with the close-by water compared to that of free acetone. The barrier for the methyl group further from water is also lower, although to a lesser degree. To gain further insights, extensive theoretical modelling was conducted, focusing on the associated large amplitude motions. Furthermore, quantum theory of atoms in molecules and non-covalent interactions analyses were utilized to visualize the underlying causes of the observed trends.

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Introduction: In total knee arthroplasty (TKA), the implant positions and knee kinematics, as well as the manifestation of medial pivot motion, play pivotal roles in determining postoperative clinical outcomes. The purpose of the current study was to analyze the correlation between knee kinematics, which was measured during TKA and implant positions derived using computed tomography (CT) examination after TKA. Methods: This study comprised 64 patients (76 knees) who underwent primary TKA between 2015 and 2022. A navigation system was used in TKA procedures, and intraoperative knee kinematics were automatically calculated with it. Utilizing three-dimensional evaluation software, positioning of implants was quantified with CT images taken pre- and post-operatively. Multiple regression analyses were employed to explore the impact of femoral component position (FP) and tibial component position (TP) on knee kinematics, focusing on the extent of tibial rotational motion (TRM) during passive knee motion. Results: FP affected TRM between knee extension and 90° flexion (p = 0.003, 95 % confidence interval [CI]: 0.315-1.384) and between knee extension and full flexion (p = 0.0002, 95 % CI: 0.654-1.844) after TKA. FP in internal rotation positively affected internal TRM after TKA. TP was not associated with TRM. Conclusions: Findings of the current study suggest that FP in internal rotation positively impacts knee kinematics after TKA.

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Purpose: The purpose of this study was to investigate the effect of anterolateral ligament reconstruction (ALLR) or lateral extra-articular tenodesis (LET) fixation at low versus high flexion angles during anterior cruciate ligament reconstruction (ACLR) on rotation or translational knee stability. Methods: The inclusion criteria for this study were (1) cadaveric study, (2) cadaveric specimens underwent ACLR, (3) cadaveric specimen underwent ALLR or LET and (4) specimen preparation technique described the knee flexion angle at the time of ALLR or LET tensioning and fixation. A priori, 'low flexion' was defined as 0-30° and 'high flexion' was defined as 60-90° at graft fixation. Main outcomes of interest included internal rotation and anterior translation. Results: Data from 92 cadaveric knees (from 9 studies) were extracted and included in the meta-analysis. The mean pooled value for internal rotation was 10.1° (95% confidence interval [CI], 5.7-14.5°) for the low flexion group and 11.5° (95% CI, 7.4-15.7°) for the high flexion group (n.s.). The mean pooled value for anterior translation was 4.3 mm (95% CI, 0.5-8.1 mm) for the low flexion group and 3.0 mm (95% CI, 1.1-5.0 mm) for the high flexion group (n.s.). Conclusion: This meta-analysis of existing biomechanical research found that the rotational and translational stability of the knee were not significantly different between scenarios in which ALLR or LET fixation was performed at low knee flexion angles (0-30°) versus high knee flexion angles (60-90°). Level of Evidence: Level IV.

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BACKGROUND: Reverse shoulder arthroplasty (RSA) offers promising functional outcomes for young patients, yet challenges persist in restoring internal rotation (IR). This study aimed to assess the restoration of IR after RSA in patients younger than 60 years of age and analyze the factors affecting IR recovery. METHODS: A retrospective multicenter study was conducted, examining the functional outcome of patients who underwent RSA, with a minimum follow-up period of 2 years. Two subgroups of patients who underwent primary RSA were analyzed separately with respect to active internal rotation with the elbow at the side (AIR1): "difficult AIR1" and "easy AIR1." RESULTS: The study included 136 patients (overall series) with a mean age of 51.6 years. The overall series showed statistically significant improvement in active range of motion (RoM), pain, and Constant scores, especially with active IR (p â€‹< â€‹0.01). According to etiology, statistically significant improvement (p â€‹< â€‹0.05) in active IR was observed for fracture sequelae, primary osteoarthritis, and rheumatoid arthritis, whereas no statistically significant improvement in IR was observed for tumor, revision, and cuff-tear arthropathy (p â€‹> â€‹0.05). In subgroup analysis, patients with easy AIR1 displayed a statistically significant lower body mass index and better Constant score mobility, as well as improved motion in forward elevation and active IR (p â€‹< â€‹0.05). No statistically significant associations were found between improved IR and prosthetic design or subscapularis repair. Scapular notch, lysis of the graft, and teres minor atrophy were significantly associated with better active IR (p â€‹< â€‹0.05). CONCLUSION: RSA improves active RoM, pain, and functional outcomes in patients aged under 60. However, the degree of improvement in IR may vary depending on several factors and the underlying etiologies. These insights are crucial for patient selection and counseling, guiding RSA optimization efforts. LEVEL OF EVIDENCE: IV.

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OBJECTIVE: To systematically review the literature on the efficacy of addressing glenohumeral internal rotation deficit (GIRD) and risk of upper-extremity injury in overhead athletes. DATA SOURCES: A search was conducted for relevant studies published in PubMed, Medline, CINAHL, Cochrane, Embase, Ovid, Google Scholar, and Web of Science. STUDY SELECTION: The review focused on randomized controlled trials (RCTSs) and quasi-experiments conducted in English language that assessed the effectiveness of GIRD and the risk of upper-extremity injury in athletes performing overhead movements. The review included 7 RCTs and 2 quasi-experiments out of 5403, which involved a total of 360 participants. DATA EXTRACTION: Two reviewers independently screened the articles, assessed methodological quality, and extracted data for analysis. The review was conducted and reported according to the Preferred Reporting Items for Systematic Reviews. All studies were assessed in duplicate for risk of bias using the Physiotherapy Evidence Database Scale for RCTs. DATA SYNTHESIS: The efficacy of different types of techniques was evaluated, including joint mobilization, sleeper stretch, cross-body stretch, myofascial release, kinesio taping, and rigid taping. These techniques showed improvement in pain score and range of motion. Furthermore, self-myofascial release tends to improve internal rotation; sleeper stretch and cross-body stretch tend to improve internal rotation with 40 percent decline in pain. However, kinesio taping and rigid taping showed positive results for internal rotation. Acute results determined that the metabolic equivalent (MET) group had significantly more horizontal adduction range of motion posttreatment compared with the control group (P=.04). No significant differences existed between MET and joint mobilizations or between joint mobilizations and the control group for horizontal adduction (P>.16). No significant between-group differences existed acutely for internal rotation (P>.28). There were no significant between-group differences for either horizontal adduction or internal rotation at the 15-minute posttests (P>.70). CONCLUSIONS: The study evaluated the efficacy of various techniques in improving pain score and range of motion in individuals with GIRD. Joint mobilization, sleeper stretch, cross-body stretch, myofascial release, kinesio taping, and rigid taping all showed improvements in pain score and range of motion. However, no significant between-group differences were found for horizontal adduction or internal rotation at the 15-minute posttests. These findings suggest that a combination of these techniques may be effective in treating individuals with GIRD.

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BACKGROUND: Reverse shoulder arthroplasty (RSA) is a common procedure for treating a variety of shoulder pathologies. However, many patients struggle with postoperative internal rotation (IR) deficits, which often hinder their activities of daily living. The conjoint tendon provides an anatomic barrier that can impede the postoperative IR of the shoulder, and this study aims to evaluate the effect of a conjoint tendon lengthening on the glenohumeral range of motion (ROM) following RSA. METHODS: This study used ten fresh-frozen cadaver specimens of the upper extremity. An RSA was implanted using a standard deltopectoral approach, and the ROM was assessed postimplantation. Following this, the conjoint tendon was identified and lengthened using a tendon sheath z-plasty, and the ROM was rerecorded. Statistical significance for the ROM gains after conjoint tendon lengthening was determined with a significance level of P < .05. RESULTS: Following the lengthening of the conjoint tendon, there were statistically significant improvements in all ROMs (P < .05). Subjects demonstrated a notable gain in IR to the back by 10.3 cm (P < .01), and all ROMs increased by at least 10°, except for forward flexion, which increased by 6° (P < .001). CONCLUSIONS: This study suggests that lengthening the conjoint tendon improves postoperative ROM of the glenohumeral joint after RSA, offering a potential solution to considerable IR deficits that are commonly encountered post-RSA. Subsequent clinical and biomechanical studies should assess the stability of the shoulder joint following conjoint tendon lengthening.

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PURPOSE: This study aimed to investigate the radiographic findings for the hip joint and hip range of motion in professional cyclists, and to determine their bone morphology and physical characteristics. The effects of physical characteristics on athletic performance were examined in terms of metabolic efficiency using simulation analysis. METHODS: We performed a case-control research study on 22 hips in 11 male professional cyclists (average age 28.5, height 1.73 m, weight 77.6 kg). Thirty hips in 15 healthy male volunteers were selected as controls. As radiographic evaluations, acetabular dysplasia was assessed on standardized radiographs. During physical evaluations, the hip range of motion was examined. We used simulation analysis to investigate the metabolic efficiency in the different cycling forms. RESULTS: The radiographic evaluations showed a significant difference in the incidence of acetabular dysplasia (p = 0.01): 59% (13/22 hips) in the pro-cyclist group versus 10% (3/30 hips) in the control group. The physical evaluations revealed significant differences in the hip internal rotation angle (p = 0.01), with greater ranges of internal rotation in the pro-cyclist group versus the control group. The simulation analyses showed that metabolism was reduced in the cycling form with hip internal rotation, especially in the lower extremities. CONCLUSIONS: Pro-cyclists showed a high frequency of acetabular dysplasia and superior hip internal rotation. According to the cycling model analyses, hip internal rotation allowed pedaling with reduced metabolic power.

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The microwave spectrum of 1-cyanopropene (crotonitrile) was remeasured using two pulsed molecular jet Fourier transform microwave spectrometers operating from 2.0 to 40.0 GHz. The molecule exists in two isomer forms, E and Z, with respect to the orientation between the methyl and the cyano groups. The spectrum of the Z isomer is more intense. Due to internal rotation of the methyl group, doublets containing A and E torsional species were found for all rotational transitions. Hyperfine splittings arising from the 14N nuclear quadrupole coupling were resolved. The heavy atom structure of the Z isomer was determined by observation of 13C and 15N isotopologue spectra in natural abundances. The experimental results were supported by quantum chemistry. The complex spectral patterns were analyzed and fitted globally, and the barriers to methyl internal rotation are determined to be 478.325(28) cm-1 and 674.632(76) cm-1 for the Z and E isomers, respectively. The non-bonded intramolecular electrostatic attraction between the methyl group and the 1-cyano substituent overcomes steric hindrance, leading to higher stability of the Z isomer. The consequence is a slight opening of 3.2° of the C(1)-C(2)-C(3) angle and a radical decrease of the methyl torsional barrier in the Z isomer due to steric repulsion.

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Overhead athletes undergo significant biomechanical adaptations due to repetitive overhead movements, primarily affecting the glenohumeral joint. These adaptations can lead to glenohumeral internal rotation deficit (GIRD), which is characterized by posterior capsule stiffness that results in glenohumeral joint translation and a shift in the center of gravity. The severity of GIRD is dependent upon the presence of asymmetry between gained external and lost internal rotation, which is defined clinically as an asymmetry exceeding 20º; this reduces the total range of motion compared to the unaffected limb or baseline measurements. Diagnosis is challenging, as it can be mistaken for chronic scapular adaptations. To mitigate misdiagnosis, a high clinical suspicion is crucial in overhead athletes, especially those who began performing forceful overhead movements before closure of growth plates. Periodic physical examinations should establish baseline values for glenohumeral rotation and track changes in glenohumeral motion to aid in diagnosis. Symptoms of GIRD include shoulder pain, stiffness, and decreased force exertion. Magnetic resonance imaging is the preferred imaging method for evaluating GIRD and assessing concomitant soft tissue pathologies. Untreated GIRD can lead to rotator cuff strength imbalances. Treatment mainly involves conservative measures, such as physical therapy, to improve internal rotation and alleviate posterior tightness. Surgical interventions are considered when symptoms persist despite conservative treatment with physical therapy or in the presence of concomitant pathologies.

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BACKGROUND: The role of tendon transfer and ideal insertion sites to improve axial rotation in reverse total shoulder arthroplasty (RTSA) is debated. We systematically reviewed the available biomechanical evidence to elucidate the ideal tendon transfer and insertion sites for restoration of external and internal rotation in the setting of RTSA and the influence of implant lateralization. PATIENTS AND METHODS: We queried the PubMed/MEDLINE, Embase, Web of Science, and Cochrane databases to identify biomechanical studies examining the application of tendon transfer to augment shoulder external or internal rotation range of motion in the setting of concomitant RTSA. A descriptive synthesis of six included articles was conducted to elucidate trends in the literature. RESULTS: Biomechanics literature demonstrates that increasing humeral-sided lateralization optimized tendon transfers performed for both ER and IR. The optimal latissimus dorsi (LD) transfer site for ER is posterior to the greater tuberosity (adjacent to the teres minor insertion); however, LD transfer to this site results in greater tendon excursion compared to posterodistal insertion site. In a small series with nearly 7-year mean follow-up, the LD transfer demonstrated longevity with all 10 shoulders having>50% ER strength compared to the contralateral native shoulder and a negative Hornblower's at latest follow-up; however, reduced electromyography activity of the transferred LD compared to the native contralateral side was noted. One study found that transfer of the pectoralis major has the greatest potential to restore IR in the setting of lateralized humerus RTSA. CONCLUSION: To restore ER, LD transfer posterior on the greater tuberosity provides optimal biomechanics with functional longevity. The pectoralis major has the greatest potential to restore IR. Future clinical investigation applying the biomechanical principles summarized herein is needed to substantiate the role of tendon transfer in the modern era of lateralized RTSA. LEVEL OF EVIDENCE: IV; systematic review.

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Background: A proposed etiology of anterior shoulder pain and limited internal rotation after reverse shoulder arthroplasty (RSA) is impingement of the humeral component on the coracoid or conjoint tendon. The primary goal of this study was to investigate radiographic surrogates for potential coracoid or conjoint tendon impingement and their relationship to postoperative pain and internal rotation after RSA. Methods: A retrospective review of a clinical registry was performed to identify patients with (1) primary RSA, (2) minimum 2-year clinical follow-up, and (3) satisfactory postoperative axillary lateral radiographs. The primary radiographic measurement of interest was the subcoracoid distance (SCD), defined as the distance between the posterior aspect of the coracoid and the anterior glenosphere. Additional measurements were as follows: anterior glenosphere overhang, posterior glenosphere overhang, native glenoid width, lateralization of glenosphere relative to the coracoid tip, lateralization shoulder angle, and distalization shoulder angle. The primary clinical outcome of interest was the 2-year postoperative Visual Analog Scale score. Secondary outcomes were (1) internal rotation (IR) defined by spinal level (IRspine), (2) IR at 90 degrees of abduction, (3) American Shoulder and Elbow Surgeons score, (4) forward flexion, and (5) external rotation at 0 degrees of abduction. Linear regression analyses were used to evaluate the relationship of the various radiographic measures on the clinical outcomes of interest. Results: Two hundred seventeen patients were included. There was a statistically significant relationship between the SCD and Visual Analog Scale scores: B = -0.497, P = .047. There was a statistically significant relationship between the SCD and IRspine: B = -1.667, P < .001. Metallic lateralization was also positively associated with improving IRspine; increasing body mass index was negatively associated. There was a statistically significant relationship between the SCD and IR at 90 degrees of abduction: B = 5.844, P = .034. Conclusion: For RSA with a 135° neck shaft angle and lateralized glenoid, the postoperative SCD has a significant association with pain and IR. Decreasing SCD was associated with increased pain and decreased IR, indicating that coracoid or conjoint tendon impingement may be an important and potentially under-recognized etiology of pain and decreased IR following RSA. Further investigations aimed toward identifying a critical SCD to improve pain and IR may allow surgeons to preoperatively plan component position to improve clinical outcomes after RSA.

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BACKGROUND: Although forward elevation, abduction, and external rotation are often successfully restored, internal rotation (IR) is frequently not satisfactorily recovered following reverse shoulder arthroplasty (RSA), affecting patients' ability to perform certain daily activities. This study examined the prevalence of limited IR in patients receiving modern RSA and its impact on clinical outcomes and patient satisfaction with their RSA. METHODS: A cross-sectional study was conducted on patients who had undergone primary RSA using a modern RSA prosthesis with a minimum 1-year follow-up. Patients returned for a research visit where they were examined for range of motion and surveyed for patient-reported outcome measures (PROMs) and subjective rating of the success level of their RSA. Postoperative range of motion data were compared with the preoperative data. The relationship of postoperative IR with PROMs and patients' subjective rating of RSA was analyzed. Logistic regression was performed to identify factors affecting patients' subjective rating of RSA. RESULTS: A total of 78 patients met the criteria and completed the study. A significant portion (59%) reported subjective IR limitations, and 41% had objective IR limitations. Comparison of preoperative and postoperative IR showed that 24% had worsened IR, whereas 33% improved. Limited IR was associated with lower patients' subjective rating of RSA and negatively affected PROMs, especially when the dominant side was operated on. Regression analysis showed that limited IR was the only independent determining factor that was significantly associated with a lower subjective rating of RSA. DISCUSSION: Despite advancements in RSA design, limited IR remains a prevalent issue, significantly affecting patients' satisfaction and clinical outcomes. This study underscores the need for setting appropriate expectations regarding IR through patient education and focused efforts to improve IR limitations in RSA patients, particularly on the dominant side.

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Background: Superior capsular release has been used to reduce tendon tension, especially in arthroscopic repair of large-to-massive rotator cuff tears. Some clinicians have used a more extensive release of capsules in arthroscopic cuff repair for adequate reduction of torn tendons to footprints. Purpose: To explore the effects of additional posterior capsular release for superior capsular release in arthroscopic repair of large-to-massive rotator cuff tears. Study Design: Cohort study; Level of evidence, 3. Methods: We compared 26 shoulders that underwent superior and posterior capsular release (group S&P) with 26 shoulders that underwent superior capsular release alone (group S) in arthroscopic repair of large-to-massive rotator cuff tears between January 23, 2013 and December 2, 2015. The visual analog scale for pain, American Shoulder and Elbow Surgeons score, Constant score, and range of motion (ROM) and muscle power were checked preoperatively and at 2 years postoperatively. Follow-up ultrasound was checked at 2 years postoperatively. Results: In both groups, the overall mean functional outcomes improved from preoperatively to postoperatively. Patients in group S&P showed more pre- to postoperative improvement than patients in group S with regard to internal rotation ROM (mean difference, 30.0° vs 20.6°; P < .001) and internal rotation power (3.4 vs 1.8 kgf; P = .001). Patients in group S had a higher retear rate on the follow-up ultrasound than patients in group S&P, but this difference did not reach statistical significance (23.1% vs 11.5%, respectively; P = .465). Conclusion: In the current study, patients who underwent superior and posterior capsular release in arthroscopic repair of large-to-massive rotator cuff tears had greater postoperative improvement in internal rotation ROM and power compared with patients who underwent superior capsular release alone.

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PURPOSE: The purpose of this study was to investigate the influence of increasing the tibial boundaries in functional alignment on femoral component orientation in total knee arthroplasty (TKA). METHODS: A retrospective review of a database of robotic-assisted TKAs using a digital joint tensioning device was performed (BalanceBot®; Corin). A total of 692 TKAs with correctable deformity were included. Functional alignment with a tibia-first balancing technique was simulated by performing an anatomic tibial resection to recreate the native medial proximal tibial angle within certain boundaries (A, 87-90°; B, 86-90°; C, 84-92°), while accounting for wear. After balancing the knee, the resulting amount of femoral component outliers in the coronal and axial plane was calculated for each group and correlated to the coronal plane alignment of the knee (CPAK) classification. RESULTS: The proportion of knees with high femoral component varus (>96°) or valgus (<87°) alignment increased from 24.5% (n = 170) in group A to 26.5% (n = 183) in group B and 34.2% (n = 237) in group C (p < 0.05). Similarly, more knees with high femoral component external rotation (>6°) or internal rotation (>3°) were identified in group C (33.4%, n = 231) than in group B (23.7%, n = 164) and A (18.4%, n = 127) (p < 0.05). There was a statistically significant (p < 0.01) overall increase in knees with both femoral component valgus <87° and internal rotation >3° from group A (4.0%, n = 28) to B (7.7%, n = 53) and C (15.8%, n = 109), with CPAK type I and II showing a 12.9- and 2.9-fold increase, respectively. CONCLUSION: Extending the tibial boundaries when using functional alignment with a tibia-first balancing technique in TKA leads to a statistically significant higher percentage of knees with a valgus lateral distal femoral angle < 87° and >3° internal rotation of the femoral component, especially in CPAK type I and II. LEVEL OF EVIDENCE: Level IV.

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INTRODUCTION: The role of the subscapularis following reverse shoulder arthroplasty (RSA) remains controversial as repair could restore adequate internal rotation and shoulder stability, but might compromise external rotation. The purpose of this multi-centre study, on a large cohort of RSAs performed using the deltopectoral approach, was to determine the effect of subscapularis preoperative status and intraoperative repair on range of motion, clinical scores and rates of complications at a minimum follow-up of 2 years. HYPOTHESIS: Repair of a functional subscapularis grants better internal rotation and stability without compromising external rotation. MATERIALS AND METHODS: We retrospectively reviewed records of all RSAs (n=916) performed by 14 surgeons that participated in a large national society symposium, and excluded 234 operated by the anterosuperior approach, 42 operated for rheumatoid arthritis, fractures, instability or post traumatic sequalae, and eight that had adjuvant latissimus dorsi tendon transfer (LDTT). This left 632 RSAs, in which the subscapularis was detached in 594, and repaired after detachment in 495. Patients completed pre- and postoperative Constant Score and postoperative Subjective Shoulder Value (SSV). Active forward elevation, active external rotation (ER), and active internal rotation (IR) were recorded pre- and postoperatively. Complications following RSA that required conservative treatment, reoperation without implant removal, as well as reoperation with implant removal were recorded. RESULTS: Of the initial cohort of 632 shoulders, 120 (19%) were lost to follow-up, 12 (2%) died due to causes unrelated to RSA, and 26 (4%) were revised with implant removal. Of the remaining 474 shoulders, 259 (55%) had a functional repaired subscapularis (Group FR), 59 (12%) had a non-functional repaired subscapularis (Group nFR), whereas 68 (14%) had a not repaired subscapularis (Group nR). Comparison of patient demographics revealed no significant differences among the three groups. Postoperative Constant Score (p=0.031) and SSV (p=0.016) were significantly different among the three groups, but effect sizes were small and not clinically relevant. Differences in postoperative ER as well as postoperative IR were not significant among the three groups: 91 (35%) gained functional IR in Group FR, 11 (19%) in Group nFR, and 13 (19%) in Group nR. Three shoulders (1.2%) reported subjective instability and 1 (0.4%) dislocated in Group FR, but none in either Groups nFR or nR. DISCUSSION: Despite statistically significant differences in Constant Score and SSV among the three groups, the clinical relevance of these differences is negligible, so repair of functional subscapularis has little or no influence on functional outcomes. During RSA by deltopectoral approach, repair of a functional subscapularis could slightly improve internal rotation in some patients but does not compromise external rotation, forward elevation or clinical scores, while repair of a non-functional subscapularis, compared to non-repair, did not improve range of motion or clinical scores. LEVEL OF EVIDENCE: III; retrospective comparative.

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