A Scapular Statistical Shape Model can Reliably Predict Premorbid Glenoid Morphology in Conditions of Severe Glenoid Bone Loss.

BACKGROUND: Knowledge of premorbid glenoid parameters at the time of shoulder arthroplasty, such as inclination, version, joint line position, height, and width, can assist with implant selection, implant positioning, metal augment sizing and/or bone graft dimensions. The objective of this study was to validate a scapular statistical shape model (SSM) in predicting patient-specific glenoid morphology in scapulae with clinically relevant glenoid erosion patterns. METHODS: Computer tomography scans of 30 healthy scapulae were obtained and used as the control group. Each scapula was then virtually eroded to create seven erosion patterns (Walch A1, A2, B2, B3, D, Favard E2, and E3). This resulted in 210 uniquely eroded glenoid models, forming the eroded glenoid group. A scapular SSM, created from a different database of 85 healthy scapulae, was then applied to each eroded scapula to predict the premorbid glenoid morphology. The premorbid glenoid inclination, version, height, width, radius of best fit sphere, and glenoid joint line position were automatically calculated for each of the 210 eroded glenoids. The mean values for all outcome variables were compared across all erosion types between the healthy, eroded, and SSM predicted groups using a two-way repeated-measures analysis of variance. RESULTS: The SSM was able to predict the mean premorbid glenoid parameters of the eroded glenoids with a mean absolute difference of 3±2° for inclination, 3±2° for version, 2±1mm for glenoid height, 2±1mm for glenoid width, 5±4mm for radius of best fit sphere, and 1±1mm for glenoid joint line. The mean SSM predicted values for inclination, version, height, width, and radius were not significantly different than the control group (P>0.05). DISCUSSION: A statistical shape model has been developed that can reliably predict premorbid glenoid morphology and glenoid indices in patients with common glenoid erosion patterns. This technology can serve as a useful template to visually represent the premorbid healthy glenoid in patients with severe glenoid bony erosions. Knowledge of the premorbid glenoid preoperatively can assist with implant selection, positioning, and sizing.

Tendon transfers in reverse total shoulder arthroplasty: A systematic review and descriptive synthesis of biomechanical studies.

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.

Single-stage revision for total shoulder arthroplasty infection. Results at a minimum 2 years follow-up.

INTRODUCTION: Similar to the management of periprosthetic joint infections of the lower limb, one-stage revision in total shoulder arthroplasty (TSA) infections is an option that has been highlighted in scientific publications since the early 2010s. However, there are only a few studies which validate this treatment and determine its scope of application in relation to two-stage treatment. HYPOTHESIS: Single-stage revision for infected TSA is a reliable treatment allowing good infection control and satisfactory functional results. METHODS: This single-center retrospective series of 34 consecutive patients operated on between 2014 and 2020 for a one-stage prosthetic revision was evaluated at a minimum of 2 years of follow-up. All of the patients included underwent revision shoulder arthroplasty during this period with the diagnosis of infection confirmed by microbiological analysis of surgical samples. Patients who did not benefit from a bipolar revision were excluded. All patients were followed at least 2 years after the intervention. Clinically suspected recurrence of infection was confirmed by a periprosthetic sample under radiographic guidance. Functional clinical outcomes as well as mechanical complications were also reported. RESULTS: The average follow-up was 40.4 months (24-102±21.6). A septic recurrence was observed in three patients (8.8%). A mechanical complication was present in four patients (14.7%), and three (11.8%) required at least one surgical revision. The mean Constant-Murley score at the last follow-up was 49 (42-57±21.83). DISCUSSION: Single-stage revision for shoulder periprosthetic joint infection results in a success rate of 91.2% with satisfactory functional results after more than 2 years of follow-up. LEVEL OF EVIDENCE: IV; retrospective study.

Insertion sites of latissimus dorsi tendon transfer performed during reverse shoulder arthroplasty: A systematic review and meta-analysis.

BACKGROUND: Reverse shoulder arthroplasty (RSA) with concurrent latissimus dorsi transfer (LDT) is a potential treatment option for restoration of external rotation (ER). Biomechanical studies have emphasized the importance of the insertion site location for achieving optimal outcomes. In this systematic review and meta-analysis, we aimed to describe what insertion sites for LDT are utilized during concomitant RSA and their associated clinical outcomes. METHODS: A systematic review and meta-analysis were performed per PRISMA guidelines. We queried PubMed/MEDLINE, Embase, Web of Science, and Cochrane databases to identify articles reporting on patients who received RSA with LDT to restore ER and specified the site of tendon transfer insertion on the humerus. We first describe reported insertion sites in the literature. Secondarily, we present preoperative and postoperative range of motion and Constant score for different insertion sites as well as reported complications. RESULTS: Sixteen studies, analyzed as 19 separate cohorts (by insertion site and tendon-transfer), reporting on 264 RSAs with LDT (weighted mean age 66 years, follow-up 39 months, 61% female) were evaluated. Of these, 143 (54%) included a concomitant teres major transfer (LDT/TMT) and 121 (46%) were LDT-only. Fourteen cohorts (14/19, 74%) reported insertion at the posterolateral aspect of the greater tuberosity, four cohorts (4/19, 21%) reported insertion site at the lateral bicipital groove, and one cohort (1/19, 5%) reported separate LDT and TMT with insertion of the TMT to the posterolateral aspect of the greater tuberosity and LDT to the lateral bicipital groove. Meta-analysis revealed no differences in range of motion or Constant score based on humeral insertion site or whether the LDT was transferred alone or with TMT. Leading complications included dislocation, followed by infection and neuropraxia. No discernible correlation was observed between postoperative outcomes and the strategies employed for tendon transfer, prosthesis design, or subscapularis management. CONCLUSION: The posterolateral aspect of the greater tuberosity was the most-utilized insertion site for LDT performed with RSA. However, in the current clinical literature, LDT with or without concomitant TMT result in similar postoperative ROM and Constant score regardless of insertion site. Analysis of various proposed transfer sites reinforce the ability of LDT with RSA to restore both FE and ER in patients with preoperative active elevation and external rotation loss. Meta-analysis revealed significant improvements in range of motion and Constant score regardless of humeral insertion site or whether the LDT was transferred alone or with TMT, although future studies are needed to determine whether an ideal tendon transfer technique exists. LEVEL OF EVIDENCE: IV.

Anterolateral Acromioplasty Reduces Gliding Resistance Between the Supraspinatus Tendon and the Coracoacromial Arch in a Cadaveric Model.

Purpose: To investigate the gliding resistance dynamics between the supraspinatus (SSP) tendon and the coracoacromial arch, both before and after subacromial decompression (anterolateral acromioplasty) and acromion resection (acromionectomy). Methods: Using 4 fresh-frozen cadaveric shoulders, acromion shapes were classified (2 type I and 2 type III according to Bigliani). Subacromial bursa and coracoacromial ligament maintenance replicated physiologic sliding conditions. Gliding resistance was measured during glenohumeral abduction (0° to 60°) in internal rotation (IR) and external rotation (ER). Peak gliding resistance between the SSP tendon and the coracoacromial arch was determined and compared between intact, anterolateral acromioplasty, and acromionectomy. Results: Peak SSP gliding resistance during abduction in an intact shoulder was significantly higher in IR than in ER (4.1 vs 2.1 N, P < .001). The mean peak SSP gliding resistance during 0° to 60° glenohumeral abduction in IR in the intact condition was significantly higher compared with the subacromial decompression condition (4.1 vs 2.8 N, P = .021) and with the acromionectomy condition (4.1 vs 0.9 N, P < .001). During 0° to 60° glenohumeral abduction in ER, mean peak SSP gliding resistance in the intact condition was not significantly different compared with the subacromial decompression condition (2.1 vs 2.0 N, P = .999). The 2 specimens with a hooked (i.e. type III) acromion showed significantly higher mean peak SSP gliding resistance during glenohumeral abduction in IR and ER when compared with the 2 specimens with a flat (i.e. type I) acromion (IR: 5.8 vs 3.0 N, P = .006; ER: 2.8 vs 1.4 N, P = .001). Conclusions: In this cadaveric study, peak gliding resistance between the SSP tendon and the coracoacromial arch during combined abduction and IR was significantly reduced after anterolateral acromioplasty and was significantly higher in specimens with a hooked acromion. Clinical Relevance: The clinical benefit of subacromial decompression remains unclear. This study suggests that anterolateral acromioplasty might reduce supraspinatus gliding resistance in those with a hooked acromion and in the typical "impingement" position.

Are glenoid retroversion, humeral subluxation, and Walch classification associated with a muscle imbalance?

BACKGROUND: The etiology of humeral posterior subluxation remains unknown, and it has been hypothesized that horizontal muscle imbalance could cause this condition. The objective of this study was to compare the ratio of anterior-to-posterior rotator cuff and deltoid muscle volume as a function of humeral subluxation and glenoid morphology when analyzed as a continuous variable in arthritic shoulders. METHODS: In total, 333 computed tomography scans of shoulders (273 arthritic shoulders and 60 healthy controls) were included in this study and were segmented automatically. For each muscle, the volume of muscle fibers without intramuscular fat was measured. The ratio between the volume of the subscapularis and the volume of the infraspinatus plus teres minor (AP ratio) and the ratio between the anterior and posterior deltoids (APdeltoid) were calculated. Statistical analyses were performed to determine whether a correlation could be found between these ratios and glenoid version, humeral subluxation, and/or glenoid type per the Walch classification. RESULTS: Within the arthritic cohort, no statistically significant difference in the AP ratio was found between type A glenoids (1.09 ± 0.22) and type B glenoids (1.03 ± 0.16, P = .09), type D glenoids (1.12 ± 0.27, P = .77), or type C glenoids (1.10 ± 0.19, P > .999). No correlation was found between the AP ratio and glenoid version (ρ = -0.0360, P = .55) or humeral subluxation (ρ = 0.076, P = .21). The APdeltoid ratio of type A glenoids (0.48 ± 0.15) was significantly greater than that of type B glenoids (0.35 ± 0.16, P < .01) and type C glenoids (0.21 ± 0.10, P < .01) but was not significantly different from that of type D glenoids (0.64 ± 0.34, P > .999). When evaluating both healthy control and arthritic shoulders, moderate correlations were found between the APdeltoid ratio and both glenoid version (ρ = 0.55, P < .01) and humeral subluxation (ρ = -0.61, P < .01). CONCLUSION: This in vitro study supports the use of software for fully automated 3-dimensional reconstruction of the 4 rotator cuff muscles and the deltoid. Compared with previous 2-dimensional computed tomography scan studies, our study did not find any correlation between the anteroposterior muscle volume ratio and glenoid parameters in arthritic shoulders. However, once deformity occurred, the observed APdeltoid ratio was lower with type B and C glenoids. These findings suggest that rotator cuff muscle imbalance may not be the precipitating etiology for the posterior humeral subluxation and secondary posterior glenoid erosion characteristic of Walch type B glenoids.

Distal insertion of the clavicular portion of pectoralis major muscle: anatomical study.

PURPOSE: Several descriptions of the anatomy of the pectoralis major (PM) have been published. However, the precise description of its distal humeral insertion, which is involved in traumatic tears, remains controversial. The distal tendon is classically described as being made of two layers, one anterior (ALPM) and one posterior (PLPM), which regroup at their distal edge. The clavicular head (CH) participates in the ALPM according to most authors. However, others describe a more superficial termination in a close relationship with the deltoid humeral insertion. The objective of this anatomical work is to precisely describe the anatomy of the CH and its relationship with the rest of the distal PM tendon and the distal deltoid tendon. MATERIALS: Twenty-three fresh cadaveric specimens were dissected (41 shoulders). The entire PM as well as the deltoid were exposed. Several measurements were collected to establish the relationships between the distal tendon of the CH and the PM, the deltoid and the bony landmarks. RESULTS: In all cases, the CH muscular portion sits on the ALPM but does not participate in the connective structure of the PM distal tendon. The inferolateral part of its distal end gives a thin tendinous portion that inserts lower on the humerus in conjunction with the distal tendon of the deltoid. In 24.4%, this tendon was more difficult to isolate but was always observed. CONCLUSIONS: The distal tendon of the PM only comes from the muscle fibres of its sternal head. The CH fibres do not contribute to this tendon but appear to terminate in a separate tendon fusing with the humeral insertion of the deltoid: the deltopectoral tendon. This could explain the different patterns of tears observed in clinical practice.

Revision rotator cuff repair: can a Sugaya III tendon considered to be healed or not.

BACKGROUND: Sugaya et al described a classification system to assess postoperative rotator cuff tendon healing. Although Sugaya I and II tendons can be considered as healed and Sugaya type IV and V can be considered as retorn, the exact status of Sugaya III tendons remains unclear. The objective of this study was to evaluate the impact of Sugaya III tendons on postoperative functional scores in a population of patients undergoing revision rotator cuff repair. METHODS: We retrospectively studied the records of all patients who underwent revision rotator cuff repair in one of 12 different institutions between July 2001 and December 2020. A total of 203 shoulders were included (59% males, mean age: 51 ± 8 years old, mean follow-up 11.5 years [range: 2-28.8 yr]). Fifty-four patients (61% males, mean age 52 ± 6 years old, mean follow-up 14.1 years [range: 10.4-28.8 yr]) had a follow-up ≥10 years (mean 14.1 years [range: 10.4-28.8 yr]) and were included in a long-term follow-up subgroup analysis. Structural integrity of the repaired tendon was evaluated on magnetic resonance imaging at last follow-up. Functional scores, acromiohumeral index (AHI), and progression of fatty infiltration and of osteoarthritis were compared according to Sugaya type. RESULTS: Mean Constant score and mean strength were significantly higher in Sugaya I and II tendons than in Sugaya III (P = .021 and .003) and Sugaya IV and V tendons (P = .07 and .038), but did not differ between Sugaya III and Sugaya IV and V tendons. Mean Subjective Shoulder Value, pain, AHI were significantly higher and fatty infiltration and progression in the Hamada classification were significantly lower in Sugaya I and II tendons and in Sugaya III than in Sugaya IV and V tendons (P < .05), but did not differ between Sugaya I and II and Sugaya III tendons. Similar characteristics could also be observed in the long-term follow-up subgroup. CONCLUSION: Sugaya III tendons after revision rotator cuff repair do not allow restoration of strength thereby impacting the Constant score. However, there seems to be a protective effect of Sugaya III tendons with regard to pain, progression of proximal migration of the humeral head, osteoarthritis, and fatty infiltration, which seems to last at long-term follow-up.

Influence of lateralized versus medialized reverse shoulder arthroplasty design on external and internal rotation: a systematic review and meta-analysis.

BACKGROUND: Restoration of external (ER) and internal rotation (IR) after Grammont-style reverse shoulder arthroplasty (RSA) is often unreliable. The purpose of this systematic review was to evaluate the influence of RSA medio-lateral offset and subscapularis repair on axial rotation after RSA. METHODS: We conducted a systematic review of studies evaluating axial rotation (ER, IR, or both) after RSA with a defined implant design. Medio-lateral implant classification was adopted from Werthel et al. Meta-analysis was conducted using a random-effects model. RESULTS: Thirty-two studies reporting 2,233 RSAs were included (mean patient age, 72.5 years; follow-up, 43 months; 64% female). The subscapularis was repaired in 91% (n=2,032) of shoulders and did not differ based on global implant lateralization (91% for both, P=0.602). On meta-analysis, globally lateralized implants achieved greater postoperative ER (40° [36°-44°] vs. 27° [22°-32°], P<0.001) and postoperative improvement in ER (20° [15°-26°] vs. 10° [5°-15°], P<0.001). Lateralized implants with subscapularis repair or medialized implants without subscapularis repair had significantly greater postoperative ER and postoperative improvement in ER compared to globally medialized implants with subscapularis repair (P<0.001 for both). Mean postoperative IR was reported in 56% (n=18) of studies and achieved the minimum necessary IR in 51% of lateralized (n=325, 5 cohorts) versus 36% (n=177, 5 cohorts) of medialized implants. CONCLUSIONS: Lateralized RSA produces superior axial rotation compared to medialized RSA. Lateralized RSA with subscapularis repair and medialized RSA without subscapularis repair provide greater axial rotation compared to medialized RSA with subscapularis repair. Level of evidence: 2A.

Long-term results of revision rotator cuff repair for failed cuff repair: a minimum 10-year follow-up study.

HYPOTHESIS: Rotator cuff repair remains associated with high retear rates, which range from 13% to 79%. The objective of this study was to evaluate the long-term clinical and structural results after revision rotator cuff repair at a minimum 10-year follow-up. METHODS: We retrospectively studied the records of all patients who underwent revision rotator cuff repair in 3 different institutions between July 2001 and December 2007 with a minimum 10-year follow-up. A total of 54 patients (61% males, mean age 52 ± 6 years old) met the inclusion criteria. Outcome measures included pain (visual analog scale [VAS]), range of motion (ROM), Subjective Shoulder Value (SSV), and the Constant score. Superior migration, osteoarthritis, and acromiohumeral interval (AHI) were assessed on standard radiographs. Fatty infiltration and structural integrity of the repaired tendon were evaluated on magnetic resonance imaging or computed tomographic arthrogram. RESULTS: At a mean 14.1 years (10.4-20.5), range of motion did not progress significantly in elevation and internal rotation between pre- and postoperation (158° [range, 100°-180°] to 164° [range, 60°-180°], P = .33, and L3 [range, sacrum-T12] to T12 [range, buttocks-T7], P = .34, respectively) and decreased in active external rotation from 45° (range, 10°-80°) to 39° (range, 10°-80°) (P = .02). However, VAS, SSV, and Constant score were all significantly improved at last follow-up (P < .001). AHI decreased significantly (P = .002) from 10 mm (7-14 mm) to 8 mm (0-12 mm). Two percent of the supraspinatus/infraspinatus tendons were Sugaya 1, 24% were Sugaya 2, 35% were Sugaya 3, 12% were Sugaya 4, and 27% were Sugaya 5. Goutallier score progressed for all muscles, but this did not reach significance and mean Goutallier remained <2 for all 4 muscles at last follow-up. Hamada score progressed from 0% >grade 2 preoperatively to 6% >grade 2 at last follow-up. CONCLUSION: Revision rotator cuff repair provides significant pain relief and improvement in functional scores at long-term follow-up. The mild progression of fatty infiltration, AHI, and Hamada score suggests that despite high retear rates (39% of stage 4 and 5 in the Sugaya classification), revision repair could possibly have a protective role on the evolution toward cuff tear arthropathy.

Non-operative management of humeral periprosthetic fracture after stemless shoulder arthroplasty.

PURPOSE: Periprosthetic fractures around a stemless implant often involve lesser and greater tuberosities with a well-fixed implant in the metaphysis. This exposes the surgeon to unique questions and challenges as no surgical option (open reduction and internal fixation or revision to a stem) appears satisfactory to address them. Purpose of this study was to evaluate the clinical outcomes after non-operative management of periprosthetic fractures after stemless shoulder arthroplasty. METHODS: A retrospective multicenter study was conducted to identify all patients who had sustained non-operative management of a periprosthetic fracture after a stemless shoulder. Exclusion criteria were as follows: (1) intraoperative fractures and (2) implant loosening. Primary outcomes included mean Constant score and mean active range of motion. Secondary outcomes were VAS, radiological analysis, and complications. RESULTS: Nine patients were included. One was excluded due to the loss of follow-up at three months. Mean age was 79 years. At the last follow-up, no significant difference was observed between the Constant score, VAS, or the range of motion before fracture and at the last follow-up. Fracture healing did not result in any change in angulation in the frontal plane in seven cases and was responsible for a varus malunion in two cases of anatomic arthroplasty. No change in lateralization or distalization was reported. No cases of implant loosening after fracture have been observed. CONCLUSIONS: Conservative management seems to be appropriate in cases of minimally displaced fractures without implant loosening.

Premorbid glenoid anatomy reconstruction from contralateral shoulder 3-dimensional measurements: a computed tomography scan analysis of 260 shoulders.

BACKGROUND: Total shoulder arthroplasty (TSA) aims to reconstruct the premorbid anatomy of a pathologic shoulder. A healthy contralateral shoulder could be useful as a template in planning TSA. The symmetry between the left and right shoulders in healthy patients remains to be proved. The purpose of this study was to compare the 3-dimensional anatomy of the glenoid between sides in a healthy population. METHODS: A multinational computed tomography scan database was retrospectively reviewed for all healthy bilateral shoulders in patients aged between 18 and 50 years. One hundred thirty pairs of healthy shoulder computed tomography scans were analyzed, and glenoid version, inclination, width, and height, as well as glenoid lateral offset and scapula lateral offset, were measured. All anatomic measures were computed with Blueprint, validated 3-dimensional planning software. The intraclass correlation coefficient was determined for each measure between left and right shoulders. The minimal detectable change (MDC) was calculated using the following formula: MDC=2×1.96×Standarderrorofmeasurement. RESULTS: The comparison between 130 pairs of healthy scapulae showed statistically significant differences in absolute values between right and left glenoid version (-5.3° vs. -4.6°, P < .01), inclination (8.4° vs. 9.3°, P < .01), and width (25.6 mm vs. 25.4 mm, P < .01), as well as scapula offset (105.8 mm vs. 106.2 mm, P < .01). Glenoid height was comparable between right and left shoulders (33.3 mm vs. 33.3 mm, P = .9). The differences between the means were always inferior to the MDC regarding glenoid version, inclination, height, and width, as well as scapula offset. Very strong intraclass correlation coefficients between the left and right shoulders were found for all evaluated paired measures. CONCLUSION: Healthy contralateral scapulae are highly reliable to predict inclination, height, width, and scapula offset and are reliable to predict version of a given scapula. Paired right and left scapulae were not statistically symmetrical regarding mean glenoid version, inclination, and width, as well as scapula offset. Nevertheless, the reported differences were not higher than the MDC for this cohort, confirming that healthy contralateral shoulders can be a useful template in TSA preoperative planning.

Full arthroscopic vs. arthroscopically assisted posterosuperior latissimus dorsi tendon transfer for shoulders with failed and irreparable rotator cuff repair: matched case-control study.

PURPOSE: To compare clinical outcomes and complication rates of full arthroscopic latissimus dorsi tendon transfer (LDTT) vs. arthroscopically assisted LDTT, for the treatment of irreparable posterosuperior massive rotator cuff tears (mRCTs) in shoulders that had failed rotator cuff repair (RCR). METHODS: We evaluated a continuous series of 191 patients who underwent LDTT over 4 consecutive years. A total of 107 patients did not have previous shoulder surgery, leaving 84 patients who had prior surgical procedures. All procedures performed over the first 2 years were arthroscopically assisted (n = 48), whereas all procedures performed over the last 2 years were full arthroscopic (n = 36). We noted all complications, as well as clinical scores and range of motion at ≥24 months. To enable direct comparison between the 2 techniques, propensity score matching was used to obtain 2 groups with equivalent age, sex, and follow-up. RESULTS: Compared with the 48 patients who underwent arthroscopically assisted LDTT, the 36 patients who underwent full arthroscopic LDTT had comparable complications (13% vs. 11%) and conversions to RSA (8.3% vs. 5.6%). Propensity score matching resulted in 2 groups, each comprising 31 patients, which had similar outcomes in terms of clinical scores (except mobility component of Constant score, which was better following fully arthroscopic LDTT; P = .037) and range of motion at a minimum follow-up of 2 years. CONCLUSION: At a minimum follow-up of 24 months, for the treatment of irreparable posterosuperior mRCTs in shoulders that had surgical antecedents, full arthroscopic LDTT had significantly better mobility component of the Constant score than arthroscopically assisted LDTT, although there were no significant differences in the other clinical or functional outcomes. Arthroscopically assisted LDTT and full arthroscopic LDTT had comparable rates of complications (8.3% vs. 13%) and conversion to RSA (5.6% vs. 8.3%).

Are glenoid retroversion, humeral subluxation and Walch classification associated with a muscle imbalance.

INTRODUCTION: The etiology of humeral posterior subluxation remains unknown, and it has been hypothesized that horizontal muscle imbalance could cause this condition. The objective of this study was to compare the ratio of anterior to posterior rotator cuff muscle and deltoid volumes as a function of humeral subluxation and glenoid morphology when analyzed as continuous variable in arthritic shoulders. METHODS: Three hundred and thirty-three (273 arthritic and 60 healthy controls) CT scans of shoulders were included in this study and were segmented automatically. For each muscle, the volume of muscle fibers without intra-muscular fat was then measured. The ratio between the volume of the subscapularis and the volume of the infraspinatus + teres minor (AP ratio) and the ratio between the anterior and posterior deltoid (APdeltoid) were calculated. Statistical analyses were performed to determine whether a correlation could be found between these ratios and glenoid version/ humeral subluxation/glenoid type in the Walch classification. RESULTS: Within the arthritic cohort, no statistically significant difference was found between the AP ratio between A and type B glenoids (1.09 ± 0.22 versus 1.03 ± 0.16 p=0.09), between A and D type glenoids (1.09 ± 0.22 versus 1.12 ± 0.27, p=0.77) nor between the A and C type glenoids (1.09 ± 0.22 versus 1.10 ± 0.19, p=1). No correlation was found between AP ratio and glenoid version/humeral subluxation (rho =-0.0360, p=0.55; rho = 0.076; p=0.21). The APdeltoid ratio of type A glenoids was significantly greater than that of type B glenoids (0.48 ± 0.15 versus 0.35 ± 0.16, p< 0.01), and type C glenoids (0.48 ± 0.15 versus 0.21±0.10, p < 0.01) but not significantly different from the APdeltoid ratio of type D glenoids (0.48 ± 0.15 versus 0.64 ± 0.34, p=1). When evaluating both healthy control and arthritic shoulders, moderate correlations were found between APdeltoid ratio and glenoid version/humeral subluxation (rho=0.55, p<0.01; rho=-0.61, p<0.01). CONCLUSION: As opposed to previous two-dimensional CT scan studies, we did not find any correlation between AP muscle volume ratio and glenoid parameters in arthritic shoulders. Therefore, rotator cuff muscle imbalance does not seem to be associated with posterior humeral subluxation leading to posterior glenoid erosion and subsequent retroversion characteristic of Walch B glenoids. However, our results could suggest that a larger posterior deltoid pulls the humerus posteriorly into posterior subluxation, but this requires further evaluation as the deltoid follows the humerus possibly leading to secondary asymmetry between the anterior and the posterior deltoid.

Correction: Bauer et al. Challenges for Optimization of Reverse Shoulder Arthroplasty Part II: Subacromial Space, Scapular Posture, Moment Arms and Muscle Tensioning. J. Clin. Med. 2023, 12, 1616.

In the original publication [...].

Dynamic Horizontal Instability of the Acromioclavicular Joint: A Case Report.

CASE: A 19-year-old female patient with a history of shoulder trauma 6 years ago presented with dynamic horizontal instability of the acromioclavicular joint (ACJ). She was treated with open ACJ reconstruction using gracilis allograft and showed a satisfactory clinical result at 1-year follow-up. CONCLUSION: Dynamic pure horizontal instability of the ACJ is a rare entity with only 6 cases reported in the literature. Till now, all reported patients who necessitated surgical treatment failed because of residual instability and/or pain. We present the seventh case of this type with a successful clinical outcome.

The association between humeral lengthening and clinical outcomes after reverse shoulder arthroplasty: a systematic review and meta-analysis.

BACKGROUND: The purpose of this study was to evaluate the relationship between humeral lengthening and clinical outcomes after reverse shoulder arthroplasty (RSA) with stratification based on measurement method and implant design. METHODS: This systematic review was performed using PRISMA-P guidelines. PubMed/Medline, Cochrane Trials, and Embase were queried for articles evaluating the relationship between humeral lengthening and clinical outcomes inclusive of range of motion (ROM), strength, outcome scores, and pertinent complications (acromial and scapular spine fractures, nerve injury) after RSA. The relationship between humeral lengthening and clinical outcomes was reported descriptively overall and stratified by measurement method and implant design (globally medialized vs. lateralized). A positive association was defined as increased humeral lengthening being associated with greater ROM, outcome scores, or a greater incidence of complications, whereas a negative association denoted that increased humeral lengthening was associated with poorer ROM, outcome scores, or a lower incidence of complications. Meta-analysis was performed to compare humeral lengthening between patients with and without fractures of the acromion or scapular spine. RESULTS: Twenty-two studies were included. Humeral lengthening was assessed as the acromiohumeral distance (AHD), the distance from the acromion to the greater tuberosity (AGT), the acromion to the deltoid tuberosity (ADT), and the acromion to the distal humerus (ADH). Of 11 studies that assessed forward elevation, a positive association with humeral lengthening was found in 6, a negative association was found in 1, and 4 studies reported no association. Of studies assessing internal rotation (n = 9), external rotation (n = 7), and abduction (n = 4), all either identified a positive or lack of association with humeral lengthening. Studies assessing outcome scores (n = 11) found either a positive (n = 5) or no (n = 6) association with humeral lengthening. Of the studies that assessed fractures of the acromion and/or scapular spine (n = 6), 2 identified a positive association with humeral lengthening, 1 identified a negative association, and 3 identified no association. The single study that assessed the incidence of nerve injury identified a positive association with humeral lengthening. Meta-analysis was possible for AGT (n = 2) and AHD (n = 2); greater humeral lengthening was found in patients with fractures for studies using the AGT (mean difference 4.5 mm, 95% CI 0.7-8.3) but not the AHD. Limited study inclusion and heterogeneity prohibited identification of trends based on method of measuring humeral lengthening and implant design. CONCLUSION: The relationship between humeral lengthening and clinical outcomes after RSA remains unclear and requires future investigation using a standardized assessment method.

Outcomes of Reverse Total Shoulder Arthroplasty with Latissimus Dorsi Tendon Transfer for External Rotation Deficit: A Systematic Review and Meta-Analysis.

BACKGROUND: Latissimus dorsi transfer (LDT) has been purported to restore motion in patients undergoing reverse shoulder arthroplasty (RSA) who have preoperative combined loss of forward elevation (FE) and external rotation (ER). This systematic review summarizes the available evidence for the functional outcomes and complications after RSA with LDT. Furthermore, the effect of implant design and whether a concomitant teres major transfer (TMT) was performed were studied. METHODS: A systematic review was performed per Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We queried PubMed/MEDLINE, Embase, Web of Science, and Cochrane databases to identify articles reporting on LDT with RSA to restore ER. Our primary outcomes were ER, FE, Constant score, and complication incidence. Secondarily, we reported postoperative internal rotation (IR) and compared ER, FE, and Constant score based on lateralized versus medialized global implant design and whether concomitant TMT was performed. RESULTS: Nineteen studies were evaluated; functional outcomes were assessed in 16 articles reporting on 258 RSAs (123 LDT, 135 LDT-TMT). Surgical indication was most commonly cuff tear arthropathy and massive irreparable cuff tear. Mean ER was -12° preoperatively and 25° postoperatively, FE was 72° preoperatively and 141° postoperatively. Mean postoperative Constant score was 65. Of 138 patients (8 studies) describing IR, only 25% reported a mean postoperative IR ≥L3. Subanalysis comparing lateralized versus medialized implants and whether TMT was concomitantly performed demonstrated no significant difference in postoperative ER, FE, and Constant score, nor preoperative to postoperative improvement in ER and FE. The complication rate was 14.1% (of 291 shoulders from 16 studies), including tear in the tendon transfer (n = 3), revision tendon repair (n = 1), nerve-related complication (n = 9), and dislocation (n = 9). CONCLUSIONS: RSA with LDT is a reliable option to restore motion, with a comparable complication rate with standard RSA. The use of medialized versus lateralized implants and whether the TM was concomitantly transferred may not influence clinical outcomes. LEVEL OF EVIDENCE: Level IV. See Instructions for Authors for a complete description of levels of evidence.

Patients with poor early clinical outcomes after anatomic total shoulder arthroplasty have sustained poor performance at 2 years from surgery.

PURPOSE: We sought to define the risk of persistent shoulder dysfunction after anatomic total shoulder arthroplasty (aTSA) beyond the early postoperative period and identify risk factors for persistent poor performance. METHODS: We retrospectively identified 144 primary aTSAs performed for primary osteoarthritis with early poor performance and 2-year minimum follow-up. Early poor performance was defined as a postoperative ASES score below the 20th percentile at 3- or 6-months (62 and 72 points, respectively). Persistent poor performance at 2 years was defined as failing to achieve the patient acceptable symptomatic state (PASS) [ASES = 81.7 points]. RESULTS: At 2-year follow-up, 51% (n = 74) of patients with early poor performance at either 3- or 6-month follow-up had persistent poor performance. There was no difference in the rate of persistent poor performance if patients were poor performers at the 3-, 6-month follow-up, or both (50% vs. 49% vs. 56%, P = .795). Of aTSAs achieving the PASS at 2-year follow-up, a greater proportion exceeded the minimal clinically important differences (MCID) [Forward elevation, external rotation, and all outcome scores] and substantial clinical benefit (SCB) [external rotation and all outcome scores] compared to persistent poor performers. However, over half of persistent poor performers still exceeded the MCID for all outcome measures (56-85%). Independent predictors of persistent poor performance were hypertension (2.61 [1.01-6.72], P = .044) and diabetes (5.14 [1.00-26.4], P = .039). CONCLUSION: Over half of aTSAs with an ASES score < 20th percentile at early follow-up had continued poor shoulder function at 2-years postoperatively. Persistent poor performance was best projected by preoperative hypertension and diabetes. LEVEL OF EVIDENCE: Level III; Retrospective Cohort Comparison using Large Database; Treatment Study.

Matched Cohort Study Comparing Arthroscopic-Assisted Versus Full-Arthroscopic Latissimus Dorsi Tendon Transfer for Irreparable Massive Rotator Cuff Tears.

Background: Latissimus dorsi tendon transfer (LDTT) is increasingly performed with arthroscopic assistance, requiring an open axillary incision, which could increase risks of infection, hematoma, and lymphoedema. Technological advancements now enable LDTT to be fully arthroscopic, but its benefits and safety have not yet been confirmed. Purpose: To compare the clinical outcomes and complication rates of arthroscopic-assisted versus full-arthroscopic LDTT for irreparable posterosuperior massive rotator cuff tears in shoulders with no surgical antecedents. Study Design: Cohort study; Level of evidence, 3. Methods: The study included 90 patients who had undergone LDTT over 4 consecutive years by the same surgeon and did not have prior surgery. During the first 2 study years, all procedures were arthroscopically assisted (n = 52), while during the last 2 years, all procedures were fully arthroscopic (n = 38). Procedure duration and all complications were recorded, as well as clinical scores and range of motion at minimum 24-month follow-up. To enable direct comparison between the techniques, propensity score matching was used to obtain 2 groups with equivalent age, sex, and follow-up. Results: From the initial cohort of 52 patients who underwent arthroscopic-assisted LDTT, 8 had complications (15.4%), of which 3 (5.7%) required conversion to reverse shoulder arthroplasty and 2 (3.8%) required drainage or lavage. From the initial cohort of 38 patients who had full-arthroscopic LDTT, 5 had complications (13.2%), of which 2 (5.2%) required conversion to reverse shoulder arthroplasty but no patients (0%) required other procedures. Propensity score matching resulted in 2 groups, each comprising 31 patients, with similar outcomes in terms of clinical scores and range of motion. The procedure time was about 18 minutes shorter for full-arthroscopic LDTT, which had different complications (2 axillary nerve pareses) as compared with arthroscopic-assisted LDTT (1 hematoma and 2 infections). Conclusion: Equivalent outcomes at minimum 24-month follow-up were found for arthroscopic-assisted and full-arthroscopic LDTT in terms of complications rates (15.4% and 13.2%, respectively), conversion to reverse shoulder arthroplasty (5.7% and 5.2%), clinical scores, and range of motion.