Impact of reverse shoulder arthroplasty design and patient shoulder size on moment arms and muscle fiber lengths in shoulder abductors.

BACKGROUND: Reverse shoulder arthroplasty (RSA) increases the moment arm of the deltoid; however, there is limited knowledge on the accompanying changes in muscle architecture that play a role in muscle force production. The purpose of this study was to use a geometric shoulder model to evaluate the anterior deltoid, middle deltoid, and supraspinatus regarding (1) the differences in moment arms and muscle-tendon lengths in small, medium, and large native shoulders and (2) the impact of 3 RSA designs on moment arms, muscle fiber lengths, and force-length (F-L) curves. METHODS: A geometric model of the native glenohumeral joint was developed, validated, and adjusted to represent small, medium, and large shoulders. Moment arms, muscle-tendon lengths, and normalized muscle fiber lengths were assessed for the supraspinatus, anterior deltoid, and middle deltoid from 0° to 90° of abduction. RSA designs were modeled and virtually implanted, including a lateralized glenosphere with an inlay 135° humeral component (lateral glenoid-medial humerus [LGMH]), a medialized glenosphere with an onlay 145° humeral component (medial glenoid-lateral humerus [MGLH]), and a medialized glenosphere with an inlay 155° humeral component (medial glenoid-medial humerus [MGMH]). Descriptive statistics were used to compare moment arms and normalized muscle fiber lengths. RESULTS: As shoulder size increased, the moment arms and muscle-tendon lengths for the anterior deltoid, middle deltoid, and supraspinatus increased. All RSA designs achieved greater moment arms for the anterior and middle deltoid, with the MGLH design achieving the largest increase. The resting normalized muscle fiber length of the anterior and middle deltoid was substantially increased in the MGLH (1.29) and MGMH (1.24) designs, shifting the operating ranges of these muscles to the descending portions of their F-L curves, whereas the LGMH design maintained a resting deltoid fiber length (1.14) and operating range similar to the native shoulder. All RSA designs demonstrated a decrease in the native supraspinatus moment arm in early abduction, with the largest decrease in the MGLH design (-59%) and minimal decrease in the LGMH design (-14%). The supraspinatus operated on the ascending limb of its F-L curve in the native shoulder and remained on this portion of the F-L curve for all RSA designs. CONCLUSION: Although the MGLH design maximizes the abduction moment arm for the anterior and middle deltoid, overlengthening of the muscle may compromise deltoid muscle force production by forcing the muscle to operate on the descending portion of its F-L curve. In contrast, the LGMH design increases the abduction moment arm for the anterior and middle deltoid more modestly while allowing the muscle to operate near the plateau of its F-L curve and maximizing its force-producing potential.

Cost-effectiveness analysis of arthroscopic Bankart repair versus open Latarjet reconstruction in anterior shoulder instability.

PURPOSE: The ideal surgical treatment for anterior shoulder instability is still under debate. In the healthcare setting, both clinical and economic factors must be considered for optimal resource allocation. From the clinical perspective, the Instability Severity Index Score (ISIS) is a helpful and validated tool for surgeons, although a gray area between 4 and 6 exists. In fact, patients with an ISIS < 4 and > 6 can be treated effectively with arthroscopic Bankart repair and open Latarjet, respectively. The purpose of this study was to conduct a cost-effectiveness analysis of arthroscopic Bankart repair versus open Latarjet in patients with an ISIS between 4 and 6. METHODS: A decision-tree model was constructed to simulate the clinical scenario of an anterior shoulder dislocation patient with an ISIS between 4 and 6. Based on previously published literature, outcome probabilities and utility values in the form of Western Ontario Instability Score (WOSI) were assigned to each branch of the tree, alongside institutional cost. The primary outcome assessed was an Incremental cost-effectiveness ratio (ICER) of the two procedures. Eden-Hybbinette was also considered in the model as a salvage procedure for failed Latarjet. A two-way sensitivity analysis was performed to identify the most impactful parameters on the ICER upon their variation within a pre-determined interval. RESULTS: Base case cost was 1245.57 € (1220.48-1270.65 €) for arthroscopic Bankart repair, 1623.10 € (1580.82-1665.39 €) for open Latarjet and 2.373.95 € (1940.81-2807.10 €) for Eden-Hybbinette. Base-case ICER was 9570.23 €/WOSI. Sensitivity analysis showed that the most impactful parameters were the utility of arthroscopic Bankart repair, the probability of success of open Latarjet, the probability of undergoing surgery after post-operative recurrence of instability and the utility of Latarjet. Of these, utility of arthroscopic Bankart repair and Latarjet had the most significant impact on the ICER. CONCLUSION: From a hospital perspective, open Latarjet was more cost-effective than arthroscopic Bankart repair in preventing further shoulder instability in patients with an ISIS between 4 and 6. Despite its several limitations, this is the first study to analyze this subgroup of patients from a European hospital setting from both an economic and clinical perspective. This study can help surgeons and administrations in the decision-making process. Further clinical studies are needed to prospectively analyze both aspects to further delineate the best strategy.

Acute versus delayed reverse total shoulder arthroplasty for proximal humeral fractures: a consecutive cohort study.

BACKGROUND: The treatment of displaced proximal humeral fractures (PHFs) remains controversial. Open reduction-internal fixation (ORIF) can be challenging, especially in elderly patients with poor bone quality, whereas hemiarthroplasty has had unpredictable outcomes. Conservative treatment may result in severe fracture sequelae with poor outcomes, requiring late reverse total shoulder arthroplasty (RTSA) in many cases. The past few years have seen a shift toward the use of RTSA for the treatment of PHFs. The aim of this study was to compare the outcomes of RTSA between patients with acute fractures and patients who underwent delayed RTSA for fracture sequelae. Our hypothesis was that the outcomes of RTSA for acute PHFs would be better than those of delayed RTSA for fracture sequelae. METHODS: We followed up 36 patients with a mean age of 79.1 years who underwent primary RTSA for acute PHFs and 56 patients with a mean age of 72.1 years who underwent RTSA in delayed fashion for fracture sequelae, including failed ORIF. The minimum follow-up period was 24 months. The mean follow-up period was 39.3 months in the acute RTSA group and 56.6 months in the delayed RTSA group. Demographic data, radiographs, and surgery data were prospectively collected and analyzed. At final follow-up, range of motion and radiographic analysis findings, as well as the Subjective Shoulder Value (SSV) and Constant score (CS), were recorded. RESULTS: The clinical results favored the group undergoing acute RTSA for acute PHFs, with a mean SSV of 8.3 of 10 and adjusted CS of 88.9% compared with a mean SSV of 8.0 of 10 and adjusted CS of 77.6% in the group undergoing late RTSA for fracture sequelae-but without statistically significant differences between the groups. Although the acute RTSA group showed slightly better range-of-motion values, no statistically significant differences were found between the groups. No intraoperative complications occurred. The time from injury to the regaining of good pain-free function was significantly shorter in the acute RTSA group. CONCLUSION: Although there were no statistically significant differences in outcomes between early RTSA for acute PHFs and late RTSA for fracture sequelae, the time from injury to the regaining of good pain-free function was significantly shorter in the acute RTSA group. Therefore, we advocate early RTSA for acute PHFs in elderly patients to provide a quicker recovery and an early return to good predictable outcomes with a much shorter period of pain and discomfort. In cases of failed conservative treatment, malunion, or failed ORIF, salvage RTSA has the potential to provide a good outcome.

The IlluminOss® photodynamic bone stabilization system for pathological osteolyses and fractures of the humerus: indications, advantages and limits in a series of 12 patients at 24 months of minimum follow-up.

BACKGROUND: Locked titanium nails are considered the reference treatment for metastatic bone lesions of the humerus in patients with aggressive histotypes, high risk of fracture or when estimated survival is lower than 6 months.Nevertheless, they are responsible for CT and MRI artifacts which interfere with postoperative radiotherapy and follow-up.The IlluminOss® is an intramedullary stabilization system which is introduced inside the humeral canal in a deflated state, and is then distended with a monomer which hardens after exposure to blue light,stabilizing the segment; it does not cause artifacts, allowing easier and more effective radiotherapy and follow-up. The aim of this study is to report our experience, indications, possible advantages and limitations of this stabilization system at 24 months of minimum follow-up in a series of 12 patients affected by pathological fractures or impending fractures of the humerus. METHODS: This is a retrospective case-series that included all patients who underwent surgery with the IlluminOss® Photodynamic Bone Stabilization System for pathological osteolyses and fractures of the humerus. Intraoperative and postoperative complications were valued. RESULTS: 12 patients and 13 procedures were included in the study. All surgeries were performed without intraoperative complications. No early postoperative complications were noted. The wounds healed in all cases and stitches were removed at two weeks from surgery, so the patients were able to perform chemotherapy after three weeks. All patients except one had a painless active range of motion which reached 90°.The VAS score was 7 preoperatively and 2.6 at one month from surgery. Pain relief was also associated to radiotherapy and chemotherapy. Unfortunately, two nail ruptures were reported at 4 and 12 months of follow-up. No artifacts were noted in the postoperative CT scans so the radiotherapy plans were easily performed without the need of dose compensation. CONCLUSIONS: The IlluminOss® intramedullary stabilization system can provide primary stability in humeral fractures and impending fractures;the surgical technique is easy and minimally invasive.Moreover,it does not present artifacts at postoperative imaging,probably giving a better chance to perform prompt radiotherapy and chemotherapy.However, randomized clinical studies are necessary to verify its potential strength and if precocious adjuvant radio- and chemotherapy are associated to a reduction of the local progression rate.

Glenoid Track Instability Management Score: Radiographic Modification of the Instability Severity Index Score.

PURPOSE: The purpose of this study is (1) to test the proposed treatment algorithm, the Glenoid Track Instability Management Score (GTIMS), which incorporates the glenoid track concept into the instability severity index score (ISIS), and (2) to compare treatment decision-making using either GTIMS versus ISIS in 2 cohorts of patients with operatively treated anterior instability. METHODS: A multicenter, retrospective review of two consecutive groups consisting of 72 and 189 patients treated according to ISIS and GTIMS, respectively, was conducted. Inclusion criteria for all patients were ≥2 confirmed traumatic anterior shoulder instability events and a physical examination demonstrating a positive anterior apprehension and relocation test. The GTIMS was graded for all 189 patients in the cohort, which uses 3-dimensional computed tomography as the sole radiographic parameter to assess on-track (0 points) versus off-track (4 points) Hill-Sachs lesions. This method differs from ISIS, which uses multiple plain radiographs for the 4-point imaging portion of the score. Outcomes scores were compared within the GTIMS and ISIS groups, as well as between them for overall comparisons based on the Western Ontario Shoulder Instability Index (WOSI), the Single Assessment Numerical Evaluation (SANE) score, and the mean rates of recurrent instability. RESULTS: A total of 261 consecutive patients from 2009 to 2014 who presented with recurrent anterior shoulder instability were treated according to either ISIS (n = 72/261, 27.6%) or GTIMS (n = 189/261, 72.4%). At a mean follow-up time of 33.2 months (range 24-49 months), the overall cohort mean ISIS of 2.9 ± 2.2 (range 0-9) was significantly higher than the mean GTIMS of 1.9 ± 1.9 (range = 0-9, P < .001). Of the 72 ISIS treated patients, 50 (69.4%) had an ISIS score of ≥ 4 and underwent a Latarjet, and the 22 patients (30.6%) with an ISIS score of < 4 underwent an arthroscopic Bankart repair. Based on GTIMS in the 189-patient cohort, using the same cutoff of 4 to indicate the need for a Latarjet, 162 patients were treated with arthroscopic Bankart repair (85.7%) and 27 with Latarjet (14.3%). The overall outcomes improved for patients treated with a Latarjet in both groups (GTIMS WOSI from 1099 [47.7% normal] to 395 [81.3% normal]; GTIMS SANE from 48 to 81; ISIS WOSI from 1050 [50% normal] to 345 [83.4% normal]; ISIS SANE from 50 to 84; P < .01). Similar positive outcomes were seen in patients treated with arthroscopic Bankart repair (GTIMS WOSI from 1062 [49.2% normal] to 402 [80.6% normal]; GTIMS SANE from 49 to 82; ISIS WOSI from 1080 [51.8% normal] to 490 [76.7% normal]; ISIS SANE from 48 to 77; P < .01). Of note, the patients with arthroscopically indicated ISIS had significantly worse outcomes scores than those treated arthroscopically according to GTIMS (P < .01). Of the 189 patients graded with GTIMS, there would have been 33 more Latarjet procedures recommended based on ISIS score. Thus the distribution of procedures based on ISIS versus GTIMS was significantly different (χ2 = 45.950; P < .001), indicating a higher rate of recommending Latarjets when using ISIS versus GTIMS. CONCLUSIONS: When ISIS scoring and plain radiograph parameters only are used, this predicted a 2-fold increase in recommending a Latarjet versus GTIMS scoring criteria, which uses advanced imaging and the on- and off-track principle to more conservatively delineate anterior instability treatment with promising postoperative patient outcomes. Overall, there were minimal differences in outcomes between GTIMS and ISIS Latarjet patients; however, better outcomes were seen in patients indicated for arthroscopic Bankart repair according to GTIMS and on-off track computed tomography scanning indications. LEVEL OF EVIDENCE: II, Prospective Cohort Study.

Bone Fragment Resorption and Clinical Outcomes of Traumatic Bony Bankart Lesion Treated With Arthroscopic Repair Versus Open Latarjet.

BACKGROUND: Bony Bankart lesions can perpetuate chronic anterior glenohumeral instability. When surgical treatment is pursued, several factors need to be considered to obtain optimal outcomes. PURPOSE: To (1) quantitatively describe patterns of bone fragment resorption and associated risk factors for developing glenoid bone loss (GBL) and (2) to compare clinical and radiological results of attritional bone loss treated with either the arthroscopic Bankart or the open Latarjet procedure. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective analysis of prospectively collected data was conducted for patients who underwent arthroscopic stabilization (group A1, 10%-20% GBL; group A2, >20% GBL) or open Latarjet (group B, >10% GBL) for recurrent shoulder instability with bony Bankart lesion. Patient characteristics, number of dislocations, and Western Ontario Shoulder Instability Index (WOSI) scores were obtained. Pre- and postoperative computed tomography imaging was used to quantitatively describe patterns of bone fragment resorption. RESULTS: A total of 120 consecutive patients (group A1, 40; group A2, 23; group B, 57) were included in the study, with a mean age of 25.6 years (range, 19-35 years). The average follow-up was 5.0 years for all groups (range, 4.83-5.16 years in group A1, 4.58-5.41 years in group A2, and 4.33-5.67 years in group B). The mean times between dislocation event and surgery were 12.8 months (range, 6-32 months) and 13.6 months (range, 6-38 months) for groups A and B, respectively. Redislocation rates were 7.5% in group A1 versus 13.0% in group A2, and only occurred in patients with ≥13.5% GBL. There were no redislocations for group B (0%). Patients had better WOSI scores in group B (234.1 ± 126.9) than in group A (576.1 ± 224.6) (P < .0001). In group A, smaller preoperative bone fragment size displayed a higher percentage of resorption after surgery (r = -0.64; P < .05). CONCLUSION: A significant inverse relationship exists between preoperative bone fragment size and percentage of postoperative resorption. Patients treated with arthroscopic bony Bankart repair who had final GBL ≥13.5% had worse outcomes. When planned GBL approaches 13.5% in high-demand patients, a smaller fragment size can result in worse clinical outcomes because of resorption. In these cases, choosing the open Latarjet procedure leads to better clinical results.

The role of bone in glenohumeral stability.

Shoulder stability depends on several factors, either anatomical or functional. Anatomical factors can be further subclassified under soft tissue (shoulder capsule, glenoid rim, glenohumeral ligaments etc) and bony structures (glenoid cavity and humeral head).Normal glenohumeral stability is maintained through factors mostly pertaining to the scapular side: glenoid version, depth and inclination, along with scapular dynamic positioning, can potentially cause decreased stability depending on the direction of said variables in the different planes. No significant factors in normal humeral anatomy seem to play a tangible role in affecting glenohumeral stability.When the glenohumeral joint suffers an episode of acute dislocation, either anterior (more frequent) or posterior, bony lesions often develop on both sides: a compression fracture of the humeral head (or Hill-Sachs lesion) and a bone loss of the glenoid rim. Interaction of such lesions can determine 're-engagement' and recurrence.The concept of 'glenoid track' can help quantify an increased risk of recurrence: when the Hill-Sachs lesion engages the anterior glenoid rim, it is defined as 'off-track'; if it does not, it is an 'on-track' lesion. The position of the Hill-Sachs lesion and the percentage of glenoid bone loss are critical factors in determining the likelihood of recurrent instability and in managing treatment.In terms of posterior glenohumeral instability, the 'gamma angle concept' can help ascertain which lesions are prone to recurrence based on the sum of specific angles and millimetres of posterior glenoid bone loss, in a similar fashion to what happens in anterior shoulder instability. Cite this article: EFORT Open Rev 2018;3:632-640. DOI: 10.1302/2058-5241.3.180028.

Bilateral posterior fracture-dislocation of the shoulder after epileptic seizure.

We present a case of a 61 year-old woman who suffered a bilateral posterior fracture-dislocation of the shoulder after an isolated episode of epileptic seizure. The patient was diagnosed at our Emergency department with x-rays and CT scans after being found unconscious. An indication for bilateral shoulder hemiprosthesis implant was initially given. However, given the peculiar pattern of the fracture, the hemiprosthesis was implanted on one side only, while the other side was treated with ORIF with four cannulated screws. After the one year, the patient had resumed her previous activities and had no complaints. We performed a review of similar cases in literature and provided a rationale for our choice of treatment and the reasons for its success.