The functional internal rotation scale: a novel shoulder arthroplasty outcome measure

Predictive factors influencing internal rotation following reverse total shoulder arthroplasty

BACKGROUND

Reverse total shoulder arthroplasty (RTSA) is increasingly used as a treatment modality for various pathologies. The purpose of this review is to identify preoperative risk factors associated with loss of internal rotation (IR) after RTSA.

METHODS

A systematic review was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Ovid MEDLINE, Ovid Embase, and Scopus were queried. The inclusion criteria were as follows: articles in English language, minimum 1-year follow-up postoperatively, study published after 2012, a minimum of 10 patients in a series, RTSA surgery for any indication, and explicitly reported IR. The exclusion criteria were as follows: articles whose full text was unavailable or that were unable to be translated to English language, a follow-up of less than 1 year, case reports or series of less than 10 cases, review articles, studies in which tendon transfers were performed at the time of surgery, procedures that were not RTSA, and studies in which the range of motion in IR was not reported.

RESULTS

The search yielded 3792 titles, and 1497 duplicate records were removed before screening. Ultimately, 16 studies met the inclusion criteria with a total of 5124 patients who underwent RTSA. Three studies found that poor preoperative functional IR served as a significant risk factor for poor postoperative IR. Eight studies addressed the impact of subscapularis, with 4 reporting no difference in IR based on subscapularis repair and 4 reporting significant improvements with subscapularis repair. Among studies with sufficient power, BMI was found to be inversely correlated with degree of IR after RTSA. Preoperative opioid use was found to negatively affect IR. Other studies showed that glenoid retroversion, component lateralization, and individualized component positioning affected postoperative IR.

CONCLUSIONS

This study found that preoperative IR, individualized implant version, preoperative opioid use, increased body mass index and increased glenoid lateralization were all found to have a significant impact on IR after RTSA. Studies that analyzed the impact of subscapularis repair reported conflicting results.

The subcoracoid distance is correlated with pain and internal rotation after reverse shoulder arthroplasty

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.

Discordance between patient-reported and objectively measured internal rotation after reverse shoulder arthroplasty

BACKGROUND

Patient satisfaction after reverse shoulder arthroplasty (RSA) partly relies on restoring functional internal rotation (IR). Although postoperative assessment of IR includes objective appraisal by the surgeon and subjective report from the patient, these evaluations may not vary together uniformly. We assessed the relationship between objective, surgeon-reported assessments of IR and subjective, patient-reported ability to perform IR-related activities of daily living (IRADLs).

METHODS

Our institutional shoulder arthroplasty database was queried for patients undergoing primary RSA with a medialized-glenoid lateralized-humerus design between 2007-2019 and minimum 2-year follow-up. Patients who were wheelchair bound or had a preoperative diagnosis of infection, fracture, and tumor were excluded. Objective IR was measured to the highest vertebral level reached with the thumb. Subjective IR was reported based on patients' rating (normal, slightly difficult, very difficult, or unable) of their ability to perform 4 IRADLs (tuck in shirt with hand behind back, wash back or fasten bra, personal hygiene, and remove object from back pocket). Objective IR was assessed preoperatively and at latest follow-up and reported as median and interquartile ranges.

RESULTS

A total of 443 patients were included (52% female) at a mean follow-up of 4.4 ± 2.3 years. Objective IR improved pre- to postoperatively from L4-L5 (buttocks to L1-L3) to L1-L3 (L4-L5 to T8-T12) (P < .001). Preoperatively reported IRADLs of "very difficult" or "unable" significantly decreased postoperatively for all IRADLs (P ≤ .004) except those unable to perform personal hygiene (3.2% vs. 1.8%, P > .99). The proportions of patients who improved, maintained, and lost objective and subjective IR was similar between IRADLs; 14%-20% improved objective IR but lost or maintained subjective IR and 19%-21% lost or maintained the same objective IR but improved subjective IR depending on the specific IRADL assessed. When ability to perform IRADLs improved postoperatively, objective IR also increased (P < .001). In contrast, when subjective IRADLs worsened postoperatively, objective IR did not significantly worsen for 2 of 4 IRADLs assessed. When examining patients who reported no change in ability to perform IRADLs pre- vs. postoperatively, statistically significant increases in objective IR were found for 3 of 4 IRADLs assessed.

CONCLUSIONS

Objective improvement in IR parallels improvements in subjective functional gains uniformly. However, in patients with worse or equivalent IR, the ability to perform IRADLs postoperatively does not uniformly correlate with objective IR. When attempting to elucidate how surgeons can ensure patients will have sufficient IR after RSA, future investigations may need to use patient-reported ability to perform IRADLs as the primary outcome measure rather than objective measures of IR.

Validity and reliability of the Thai functional internal rotation scale for shoulder arthroplasty

Background

The Functional Internal Rotation Scale is an excellent clinical tool for evaluating patients with shoulder arthroplasty, but it has not been adapted to the Thai version. The objectives of this study were to translate the English version and culturally adapt the Functional Internal Rotation Scale to the Thai version and to examine the psychometric properties of the Thai Functional Internal Rotation Scale among Thai participants having shoulder arthroplasty.

Methods

The Functional Internal Rotation Scale was translated to Thai, including cross-cultural adaptations, following standard guidelines. Psychometric properties were evaluated with shoulder arthroplasty patients. Content validity was evaluated using the content validity index (CVI). Criterion validity was assessed using the Pearson correlation coefficient. An Independent t-test was used to evaluate construct validity. Internal consistency reliability was assessed using Cronbach's alpha coefficient. Intraclass correlation coefficient (ICC) was used to determine test-retest reliability over a 14-day interval.

Results

Of 45 participants, 20 total shoulder arthroplasty (TSA) patients and 25 reverse shoulder arthroplasty (RSA) patients, the majority of participants were female (69%) and retired (91%) with a mean age of 72.9 years (SD 9.1). CVI evaluation was acceptable, with a total CVI of 0.92. The correlation of the Thai Functional Internal Rotation Scale with the Thai version of the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (Thai ASES) and the internal rotation subscale (IR subscale) of the Thai ASES was 0.73 (P < 0.001) and 0.75 (P < 0.001), respectively. For construct validity, TSA patients scored, on average, 10.8 points higher than RSA patients (43.7 vs. 32.9, P < 0.001, 95% confidence interval 6.3-15.3). Cronbach's alpha coefficient of the Thai Functional Internal Rotation Scale was 0.95. The test-retest reliability revealed excellent reliability (ICC 0.99).

Conclusion

The Thai Functional Internal Rotation Scale has good validity and excellent reliability in assessing internal rotation function in Thai shoulder arthroplasty patients.

Challenges for Optimization of Reverse Shoulder Arthroplasty Part I: External Rotation, Extension and Internal Rotation

A detailed overview of the basic science and clinical literature reporting on the challenges for the optimization of reverse shoulder arthroplasty (RSA) is presented in two review articles. Part I looks at (I) external rotation and extension, (II) internal rotation and the analysis and discussion of the interplay of different factors influencing these challenges. In part II, we focus on (III) the conservation of sufficient subacromial and coracohumeral space, (IV) scapular posture and (V) moment arms and muscle tensioning. There is a need to define the criteria and algorithms for planning and execution of optimized, balanced RSA to improve the range of motion, function and longevity whilst minimizing complications. For an optimized RSA with the highest function, it is important not to overlook any of these challenges. This summary may be used as an aide memoire for RSA planning.

A pilot-study focusing on internal rotation after reverse total shoulder arthroplasty using the Activities of Daily Living which require Internal Rotation (ADLIR) score

Background

Loss of internal rotation remains an issue after reverse total shoulder arthroplasty (RTSA). Our goal is to define the expected functional internal rotation after RTSA using the Activities of Daily Living which require Internal Rotation (ADLIR) score in a homogenous population of patients treated with RTSA.

Methods

35 patients with a minimum follow-up of two years after RTSA were evaluated using the ADLIR and Constant-Murley questionnaires. A correlation between the ADLIR and Constant score was investigated and the internal validity of the ADLIR score used in a RTSA patient population was measured using Cronbach's alpha coefficient. The impact of internal rotation on the total rotational arc of motion was defined.

Results

Excellent results were recorded for both the Constant score (79 ± 18) and ADLIR score (88 ± 16). Pearson's correlation coefficient was r = 0,84 (p-value <0,001). The ADLIR score showed a high reliability for all questions.

Conclusions

The ADLIR score has proven to be a useful addition in the post-operative evaluation of patients treated with RTSA. Further studies are needed to investigate the evolution of the ADLIR score from pre- to postoperatively in order to determine the clinical and predictive value of this score.

Level of evidence

Level IV - Observational study.

Functional internal rotation is similar between lesser tuberosity osteotomy and subscapularis peel in total shoulder arthroplasty: short-term follow-up

INTRODUCTION

Lesser tuberosity osteotomy (LTO) and subscapularis peel (Peel) are 2 common techniques used to mobilize the subscapularis tendon during anatomic total shoulder arthroplasty (TSA). The literature is inconclusive over which technique is optimal; thus, controversy exists over which technique should be performed. The purpose of this study was to compare specific functional internal rotation tasks and general outcome scores in TSA patients who received either an LTO or Peel.

METHODS

A retrospective review of 563 patients treated with primary TSA using either an LTO (n = 358) or Peel (n = 205) with a minimum 2-year follow-up was performed. Subjective internal rotation, active internal rotation, and specific questions related to functional internal rotation isolated from the Simple Shoulder Test (SST) and American Shoulder and Elbow Surgeons functional questionnaires were reviewed. Other outcome scores including visual analog scale pain and function, Single Assessment Numerical Evaluation, SST, American Shoulder and Elbow Surgeons, and revision rates were compared between the 2 groups.

RESULTS

The study found no difference in postoperative functional internal rotation and range of motion between LTO and Peel. Patients who received a Peel were shown to have a slightly greater improvement in the ability to perform toileting and a higher average change in SST score that did not reach clinical significance. There was no difference in the percentage of maximal improvement, revision rate, or need for revision between the 2 groups.

CONCLUSION

No difference was found between the LTO and Peel techniques in regard to functional tasks of internal rotation at short-term follow-up.

Factors associated with improvement or loss of internal rotation after reverse shoulder arthroplasty

BACKGROUND

Internal rotation (IR) with reverse total shoulder arthroplasty (rTSA) can be unpredictable. Identifying the factors associated with loss of or improved IR could aid preoperative patient counseling. This study quantifies the change in IR experienced by rTSA patients with nonfracture indications and identifies the patient, implant, and operative factors associated with IR loss or gain at 2-year minimum follow-up.

METHODS

A total of 1978 primary rTSA patients were analyzed from an international database of a single rTSA prosthesis to quantify IR at 2 years' minimum follow-up. rTSA patients were divided into 2 cohorts based on their preoperative IR score, with group 1 patients having less active IR as defined by a preoperative IR score ≤3 and group 2 patients having greater active IR as defined by a preoperative IR score ≥4 (ie, L5 or higher). For both group 1 and 2 patients, univariate and multivariate analyses were performed to quantify the risk factors associated with IR loss after rTSA.

RESULTS

Overall, 58.9% of rTSA patients experienced IR improvement and 17.0% lost IR after rTSA. The occurrence of IR loss or gain was dependent on preoperative IR score, as 73.2% of group 1 patients improved IR and only 40.1% of group 2 patients improved IR, whereas 31.0% of group 2 patients lost IR and only 6.3% of group 1 patients lost IR after rTSA. Numerous risk factors for IR loss were identified. For group 1 patients, male sex (P = .004, odds ratio [OR] = 2.056), tobacco usage (P = .004, OR = 0.348), larger humeral stem diameter (P = .008, OR = 0.852), and not having subscapularis repaired (P = .002, OR = 2.654) were significant risk factors for IR loss. For group 2 patients, male sex (P = .005, OR = 1.656), higher body mass index (P = .002, OR = 0.946), a diagnosis other than osteoarthritis (P < .001, OR = 2.189), nonaugmented baseplate usage (P < .001, OR = 2.116), and not having subscapularis repaired (P < .001, OR = 3.052) were significant risk factors for IR loss.

CONCLUSION

The majority of patients improve IR after rTSA in the nonfracture setting. rTSA patients with substantial IR prior to surgery had a greater probability for losing IR compared to patients with poor preoperative IR. Numerous risk factors for IR loss were identified; these risk factors are useful for counseling patients considering rTSA, as some patients are more likely to lose IR than others.

Using machine learning to predict internal rotation after anatomic and reverse total shoulder arthroplasty

BACKGROUND

Improvement in internal rotation (IR) after anatomic (aTSA) and reverse (rTSA) total shoulder arthroplasty is difficult to predict, with rTSA patients experiencing greater variability and more limited IR improvements than aTSA patients. The purpose of this study is to quantify and compare the IR score for aTSA and rTSA patients and create supervised machine learning that predicts IR after aTSA and rTSA at multiple postoperative time points.

METHODS

Clinical data from 2270 aTSA and 4198 rTSA patients were analyzed using 3 supervised machine learning techniques to create predictive models for internal rotation as measured by the IR score at 6 postoperative time points. Predictions were performed using the full input feature set and 2 minimal input feature sets. The mean absolute error (MAE) quantified the difference between actual and predicted IR scores for each model at each time point. The predictive accuracy of the XGBoost algorithm was also quantified by its ability to distinguish which patients would achieve clinical improvement greater than the minimal clinically important difference (MCID) and substantial clinical benefit (SCB) patient satisfaction thresholds for IR score at 2-3 years after surgery.

RESULTS

rTSA patients had significantly lower mean IR scores and significantly less mean IR score improvement than aTSA patients at each postoperative time point. Both aTSA and rTSA patients experienced significant improvements in their ability to perform activities of daily living (ADLs); however, aTSA patients were significantly more likely to perform these ADLs. Using a minimal feature set of preoperative inputs, our machine learning algorithms had equivalent accuracy when predicting IR score for both aTSA (0.92-1.18 MAE) and rTSA (1.03-1.25 MAE) from 3 months to >5 years after surgery. Furthermore, these predictive algorithms identified with 90% accuracy for aTSA and 85% accuracy for rTSA which patients will achieve MCID IR score improvement and predicted with 85% accuracy for aTSA patients and 77% accuracy for rTSA which patients will achieve SCB IR score improvement at 2-3 years after surgery.

DISCUSSION

Our machine learning study demonstrates that active internal rotation can be accurately predicted after aTSA and rTSA at multiple postoperative time points using a minimal feature set of preoperative inputs. These predictive algorithms accurately identified which patients will, and will not, achieve clinical improvement in IR score that exceeds the MCID and SCB patient satisfaction thresholds.

Hybrid Glenoid Designs in Anatomic Total Shoulder Arthroplasty: A Systematic Review

BACKGROUND

Hybrid glenoid components in total shoulder arthroplasty (TSA) utilize both polyethylene and metal components to provide short-term stability and long-term biologic fixation through bone ingrowth.

QUESTIONS/PURPOSE

We sought to systematically review the literature for studies that assessed outcomes of TSA performed using hybrid glenoid components.

METHODS

PubMed, Medline, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Embase were searched systematically for articles measuring clinical and patient-reported outcomes and rates of complication and revision following TSA using a hybrid glenoid component.

RESULTS

Seven studies with 593 shoulders were included in this review. The mean age of patients was 65 ± 1 years, and 46% of the population was male. Mean follow-up was 50 months (4.2 years). The overall complication rate was 7% and rate of revision was 2.5%; glenoid radiolucency was present in 33% of shoulders at mean follow-up of 50 months. Mean improvements in forward elevation, external rotation, internal rotation score, and abduction were 49°, 28°, 2 points, and 42°, respectively. Mean improvements in Constant, American Shoulder and Elbow Surgeons (ASES), and University of California, Los Angeles (UCLA) scores were 36 points, 52 points, and 17 points, respectively.

CONCLUSION

Our review found that TSA using hybrid glenoid components results in low rates of complication and revision at early follow-up. Long-term studies are warranted to understand more fully the role of hybrid glenoid components in TSA.

Relationship between postoperative integrity of subscapularis tendon and functional outcome in reverse shoulder arthroplasty

HYPOTHESIS AND BACKGROUND

The role of the subscapularis in reverse shoulder arthroplasty (RSA) remains controversial. Studies have shown that subscapularis repair has no significant influence on the functional outcomes of patients. However, few studies have assessed the postoperative integrity of the subscapularis tendon after RSA. The aims of this study were to investigate the postoperative healing of the subscapularis after RSA via ultrasound and to evaluate the relationship between tendon integrity and functional outcomes. We hypothesized that subjects with a healed subscapularis after RSA would have higher Constant scores and better internal rotation (IR) than those without a healed subscapularis.

METHODS

This was a retrospective review of all patients who underwent primary RSA with subscapularis tenotomy repair performed by a single surgeon with a minimum 2-year follow-up period. The inclusion criteria were (1) primary RSA and (2) complete intraoperative repair of the subscapularis tenotomy if the tendon was amenable to repair. The total Constant score and active and passive range of motion were measured preoperatively and at every postoperative visit. IR was further subcategorized into 3 functional types (type I, buttock or sacrum; type II, lumbar region; and type III, T12 or higher). The integrity of the subscapularis on ultrasound at 2 years was reported using the Sugaya classification. The correlation between subscapularis integrity and functional outcomes including functional IR was evaluated.

RESULTS

A total of 86 patients (mean age, 73 ± 7.4 years; age range, 50-89 years) were evaluated. The mean postoperative Constant score for all patients significantly improved from 38 points to 72 points (P < .001) at last follow-up (mean, 3.3 years). There was significant improvement in all Constant score functional subscales and in terms of range of motion. The rate of sonographic healing of the subscapularis was 52.6%. There was no difference in Constant scores between "intact" and "failed" tendon repairs; however, intact tendons demonstrated significantly better IR with no difference in external rotation (P < .01).

CONCLUSION

The healing rate of the subscapularis following RSA was only 52.6%. IR function in patients with an intact subscapularis at 2 years after RSA was significantly better than in patients with failed or absent tendon repairs. Primary repair of reparable subscapularis tendons during RSA should be strongly considered.

Glenoid lateralization influences active internal rotation after reverse shoulder arthroplasty

BACKGROUND

Improvement in internal rotation (IR) is not reliably achieved after reverse total shoulder arthroplasty (RSA). The purpose of this study was to evaluate the relationship between postoperative IR and glenoid-sided lateralization following RSA in an implant using metallic lateralization.

METHODS

A multicenter retrospective study of RSAs with minimum 1-year clinical follow-up was performed. Patients were stratified based on the amount of glenoid-sided implant lateralization into 4 groups: 0-2 mm (n = 57), 4 mm (n =238), 6 mm (n = 95), and 8 mm (n = 65). The primary study outcome was active IR at a minimum of 1 year postoperatively, measured both by spinal level and in degrees with the shoulder abducted to 90°. Secondary outcomes were active forward flexion and external rotation, belly press strength, and subjective patient-reported outcome (PRO) measures. Comparisons were made with 1-way analyses of variance. Linear regression analyses evaluating for the association of glenoid lateralization with active IR were also performed to control for additional confounders, including demographics and other implant variables such as glenosphere diameter, humeral lateralization, humeral version, and whether the subscapularis was repaired.

RESULTS

A total of 455 patients were included in the study. The mean age was 69 years, and 48% of patients were male. IR differences varied by the method of measurement (spinal level vs. IR in degrees with arm abducted). Overall, patients with 8 mm of glenoid lateralization had significantly improved IR compared with all other lateralization groups. Patients with 6 mm of glenoid lateralization had significantly improved IR compared with the 0-2- and 4-mm groups. There were no significant differences in the secondary outcomes or PROs between lateralization groups. In the regression analysis, glenoid lateralization was the only implant-related variable that was significantly associated with improved IR for both measurement methods. Glenosphere diameter and humeral version were both significantly associated with IR measured in degrees with the arm abducted but not spinal level.

CONCLUSIONS

For the studied implant system, glenoid lateralization of 6-8 mm was associated with improved active IR at 1 year compared to patients with less glenoid lateralization with no significant differences in active forward flexion, external rotation, or PROs. In a multivariable analysis, increased humeral retroversion was associated with increased IR at 90° and increasing glenosphere diameter was associated with decreased IR at 90°, whereas BMI, subscapularis repair, and humeral lateralization did not significantly affect active IR.

Comparing patient-reported outcome measures and physical examination for internal rotation in patients undergoing reverse shoulder arthroplasty: does surgery alter patients' perception of function?

BACKGROUND

The purpose of this study was to evaluate how patients treated with reverse shoulder arthroplasty (RSA) achieve internal rotation (IR) using video assessment and to compare this to patient-reported outcome measures (PROMs).

METHODS

We reviewed 215 preoperative and 657 postoperative videos (3-78 months) for 215 patients who underwent primary RSA, performing IR using the modified vertebral level method. Their functional motion pattern was then grouped into 3 types: type I, could not reach behind their back; type II, able to reach to at least waist level, with assistance; and type III, able to reach to a minimum of waist level in an uninterrupted fashion. Patients completed functional questions (put on a coat, wash back, tuck in a shirt, and manage toileting) and a diagram of perceived IR. Patients' functional motion types were compared to PROM answers. Pre- and postoperative scores were also compared to assess the effect of surgery on patients' perception of IR function.

RESULTS

Patients undergoing RSA will achieve IR in 3 distinct motion patterns. Analysis of self-reported IR indicated statistically significant difference between the 3 functional types of IR (P < .001). Patient-perceived IR was not significantly different between the 3 studied IR functional types (P = .076) in the analysis of preoperative measures but was significantly different in the postoperative setting (P < .001).

CONCLUSION

Patients attempt IR in 3 distinct functional motion patterns. The improvement of IR after RSA is measured better by patient questionnaires than by physical examination.