Simple Shoulder Test

Abstract

The Simple Shoulder Test (SST) is one of the most widely implemented, validated, and enduring patient-reported outcome measures (PROMs) in orthopaedic surgery, physical therapy, and rheumatology. Originally developed in 1993 by Steven B. Lippitt, Douglas T. Harryman II, and Frederick A. Matsen III at the University of Washington, the instrument was conceived to capture functional limitations and pain-related disability affecting the glenohumeral joint and upper extremity. Comprising 12 dichotomously scored (Yes/No) items, the SST evaluates both baseline comfort (at rest and during sleep) and the capacity to execute discrete, hierarchically organized functional activities ranging from basic hygiene (e.g., tucking in a shirt, washing the opposite shoulder) to resisted elevation, heavy load bearing (carrying 20 lbs), and ballistic athletic maneuvers (throwing a ball 20 yards). Over three decades of psychometric evaluation across diverse populations—including individuals with rotator cuff tears, glenohumeral osteoarthritis, adhesive capsulitis, and shoulder arthroplasty—have confirmed its robust psychometric profile. The instrument demonstrates strong internal consistency (Kuder-Richardson 20 coefficients typically between 0.79 and 0.88), excellent test-retest reliability (intraclass correlation coefficients ranging from 0.85 to 0.94), and established construct and convergent validity when compared against complex measures such as the American Shoulder and Elbow Surgeons (ASES) Shoulder Score, the Constant-Murley Score, the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, and the Short Form 36 (SF-36). Rasch and factor analytic investigations frequently validate its predominantly unidimensional functional continuum while revealing hierarchical item difficulty. Due to its minimal respondent burden, administrative ease, and high sensitivity to post-surgical intervention, the SST remains a gold-standard functional inventory in orthopaedic research and longitudinal registry monitoring.

Keywords

Simple Shoulder Test, SST, patient-reported outcome measure, shoulder functional assessment, rotator cuff tear, shoulder arthroplasty, upper extremity disability, psychometric validation, orthopaedic clinical trials, functional capacity evaluation

Authors

The Simple Shoulder Test was developed by a team of orthopaedic surgeons and biomechanical investigators at the Department of Orthopaedics and Sports Medicine, University of Washington School of Medicine, Seattle, Washington, USA:

• Steven B. Lippitt, MD — Department of Orthopaedics and Sports Medicine, University of Washington; subsequently affiliated with the Cleveland Clinic Akron General, Department of Orthopaedic Surgery, Akron, OH, USA.
• Douglas T. Harryman II, MD — Late Associate Professor, Shoulder and Elbow Service, Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA, USA.
• Frederick A. Matsen III, MD — Professor and Chair Emeritus, Shoulder and Elbow Service, Department of Orthopaedics and Sports Medicine, University of Washington Medical Center, Seattle, WA, USA.

Notable cross-cultural validations, including the Dutch adaptation, were spearheaded by Dirk Jan (D.A.) van Kampen, MD, PhD, and colleagues (2012) at the Department of Orthopaedic Surgery, Tergooi Hospitals, Hilversum/Blaricum, and Leiden University Medical Center, The Netherlands.

Purpose

The fundamental purpose of the Simple Shoulder Test (SST) is to systematically inventory, quantify, and track patient-perceived functional limitations arising from shoulder pathology. In both clinical practice and clinical research, physicians and therapists require an objective, reproducible metric that captures how shoulder impairment translates into real-world functional disability. Prior to the early 1990s, the predominant evaluation systems relied heavily upon clinician-measured physical parameters, such as passive range of motion measured via goniometry and manual muscle strength grading. Pioneering systems such as Charles Neer’s evaluation protocol and the early iterations of the American Shoulder and Elbow Surgeons (ASES) scoring system blended subjective symptoms with physician-derived physical examination metrics. However, methodological research revealed that clinician-assessed range of motion and strength suffer from significant inter-observer variability, fail to mirror the patient’s lived functional capacity, and often correlate weakly with patient satisfaction and return to occupational or recreational activities.

To overcome these limitations, Lippitt, Harryman, and Matsen formulated the SST to serve as an ultra-brief, fully self-administered instrument requiring no clinical tools, goniometers, or clinician mediation. By shifting the assessment paradigm entirely to the patient, the SST eliminates clinician bias and captures functional competence directly. The scale was purposefully designed to fulfill several distinct clinical and scientific mandates:

• Diagnostic and Severity Stratification: Quantifying baseline upper extremity functional impairment across a broad spectrum of orthopaedic conditions, such as full-thickness rotator cuff tears, subacromial impingement syndrome, glenohumeral osteoarthritis, proximal humerus fractures, and recurrent glenohumeral instability.
• Longitudinal Outcome Monitoring: Serving as an evaluative measure capable of detecting clinically meaningful change over time following non-operative physical rehabilitation, subacromial injections, open or arthroscopic rotator cuff repair, labral stabilization, and anatomical or reverse total shoulder arthroplasty (TSA/rTSA).
• Comparative Effectiveness Research and Registries: Offering an efficient, standardized measurement tool suited for high-volume multicenter trials, national joint replacement registries, and institutional quality improvement initiatives where lengthier instruments (such as the 30-item DASH) impose excessive administrative or cognitive burden.
• Shared Decision-Making: Allowing patients and clinicians to pinpoint specific functional deficits—such as inability to sleep without pain, reach overhead, or carry household loads—thereby aligning therapeutic and surgical goals with the patient’s individual functional priorities.

Psychological Construct

The Simple Shoulder Test measures the multifaceted construct of shoulder-specific functional capacity and perceived physical disability. Within health psychology and behavioural medicine, perceived disability is conceptualized not merely as a mechanical consequence of structural tissue injury, but as a complex interplay between nociceptive signalling, biomechanical efficiency, task-specific self-efficacy, and psychological adaptation.

The items of the SST sample specific behavioral and physiological domains that delineate this construct:

1. Basal Comfort and Pain Interference

Items 1 and 2 target nocturnal comfort and rest-state comfort: “Is your shoulder comfortable with your arm at rest by your side?” and “Does your shoulder allow you to sleep comfortably?” Pain at rest reflects basal joint inflammation, capsular tension, or uncompensated mechanical pathology. Sleep disturbance, in particular, is a cardinal symptom of shoulder pathology—often linked to nocturnal increases in inflammatory cytokines, intra-articular pressure changes in the decubitus position, and lack of postural relaxation. Psychologically, nocturnal pain exacerbates depressive symptomatology, catabolic stress reactivity, and hyperalgesia, compounding the patient’s perception of physical limitation.

2. Range of Motion and Basic Hygiene (ADLs)

Items 3, 4, 5, and 11 evaluate rotational and elevation movements essential for independent daily functioning: reaching the small of the back to tuck in a shirt (internal rotation and extension), placing the hand behind the head with the elbow out (external rotation and abduction), placing a coin on a shoulder-height shelf without bending the elbow (forward elevation/flexion), and washing the posterior aspect of the opposite shoulder (cross-body adduction and internal rotation). These tasks assess active kinematic integrity, soft-tissue compliance, and neuromuscular control across key spatial sectors. Inability to execute these tasks signals severe capsular restriction (e.g., adhesive capsulitis) or structural loss of force couples (e.g., massive rotator cuff tears), heavily undermining the individual’s perceived self-care independence.

3. Resisted Musculoskeletal Elevation and Strength Capacity

Items 6, 7, and 8 introduce calibrated mechanical loads to the lever arm: lifting 1 lb. (a full pint container) to shoulder level with an extended elbow, lifting 8 lbs. (a full gallon container) in the same posture, and carrying 20 lbs. at the side with the affected limb. From a biomechanical perspective, extending an elbow with a 1 lb. or 8 lb. weight creates an external torque around the glenohumeral joint that requires substantial supraspinatus, infraspinatus, and deltoid co-activation, alongside scapular stabilization. Carrying 20 lbs. at the side assesses inferior stability, trapezius/rhomboid suspensory competence, and tolerance to axillary traction. Psychologically, these items tap into the patient’s fear of reinjury or movement-evoked pain (kinesiophobia), testing confidence in dynamic force transmission under load.

4. Dynamic Ballistic Function and Occupational Role Enactment

Items 9, 10, and 12 assess high-demand physical capacities: tossing a softball underhand 10 yards, throwing a baseball overhand 20 yards, and working full-time at one’s regular job. Ballistic movements demand coordinated kinetic chain activation, rapid muscular acceleration/deceleration, and rotational stability under dynamic stress. Item 12 assesses broad occupational role performance, synthesizing pain, endurance, and physical competence into a holistic societal participation domain. Deficits here capture advanced levels of functional disability that delineate between sedentary daily adequacy and demanding occupational or recreational health.

Theoretical Framework

The Simple Shoulder Test is rooted in classical disablement models and modern psychometric measurement paradigms, predominantly bridging the Nagi Disablement Scheme, the World Health Organization’s International Classification of Functioning, Disability and Health (ICF), and Guttman Scaling Theory.

The ICF and Disablement Paradigm

The WHO ICF model distinguishes between:

1. Body Functions and Structures (anatomical integrity of the rotator cuff, labrum, and glenohumeral cartilage; sensory inputs like pain),
2. Activities (execution of specific tasks such as lifting, reaching, carrying, and tossing), and
3. Participation (involvement in life situations, such as full-time employment and recreational sports).

The SST intentionally shifts the primary evaluative focus away from anatomical pathology (which often demonstrates poor correlation with subjective functional limitations) to Activity Limitations and Participation Restrictions. By evaluating functional competencies through concrete everyday tasks, the SST provides an operational bridge connecting the patient’s underlying impairment to their functional independence.

Guttman Scaling and Hierarchical Task Complexity

A central theoretical premise embedded in the design of the SST by Lippitt and Matsen is the concept of a deterministic, hierarchical difficulty gradient, closely related to the Guttman scale. The 12 items were structured to span a graduated spectrum of physical difficulty. For instance, resting the arm comfortably at the side represents an entry-level functional demand, followed sequentially by unweighted reach (coin on shelf), light load elevation (1 lb.), moderate load elevation (8 lbs.), and finally ballistic overhead projection (throwing a baseball 20 yards). Under Guttman theory, an individual who successfully performs a high-difficulty task (e.g., throwing a baseball 20 yards) is theoretically expected to endorse all preceding, less demanding tasks (e.g., placing a coin on a shelf or lifting 1 lb.). While biological variation, specific pathology patterns (e.g., isolated loss of internal rotation versus loss of forward elevation), and compensatory strategies introduce some deviation from a pure deterministic Guttman progression, modern psychometric evaluations using Item Response Theory (IRT) and Rasch modelling have largely confirmed the underlying hierarchical ordering of these functional thresholds.

Validity

The psychometric validity of the Simple Shoulder Test has been extensively evaluated across diverse surgical cohorts, rehabilitation environments, and language adaptations.

Content and Face Validity

Content validity was established during the instrument’s initial development through systematic item extraction from historical shoulder rating indices—notably the Neer scoring system and the ASES evaluation form—supplemented by clinical consensus among experienced shoulder surgeons and prospective feedback from patients with documented shoulder dysfunction. The 12 items were selected because they represent universally recognizable functional benchmarks that encompass both fundamental self-care tasks and higher-demand occupational activities.

Construct and Convergent Validity

Construct validity is evidenced by strong, theoretically coherent correlations between the SST total score and established shoulder and upper-extremity instruments:

• ASES Shoulder Score: The SST correlates strongly with the ASES index, with Pearson and Spearman correlation coefficients consistently reported between $r = 0.70$ and $r = 0.84$ in patients undergoing rotator cuff repair and total shoulder arthroplasty (Matsen et al., 2008; Godfrey et al., 2007).
• Constant-Murley Score: Moderate to strong correlations ($r = 0.65 – 0.78$) are observed with the Constant score. The SST strongly parallels the subjective parameters (pain and activities of daily living) and active motion subcomponents of the Constant score, though correlations are slightly lower with isolated dynamometer-measured strength.
• DASH and QuickDASH: The SST displays an inverse correlation with the DASH (where higher scores indicate greater disability), with reported values ranging from $r = -0.72$ to $r = -0.85$, demonstrating alignment regarding upper limb impairment.
• SF-36 Physical Component Summary (PCS): When mapped against general health surveys, the SST shows moderate to strong convergence with the SF-36 PCS ($r = 0.52 – 0.68$), while showing minimal correlation with the SF-36 Mental Component Summary (MCS, $r = 0.12 – 0.28$), confirming divergent/discriminant validity.

Known-Groups and Discriminative Validity

The SST reliably distinguishes between clinically distinct patient groups. Preoperative SST scores differ significantly between patients presenting with massive, irreparable rotator cuff tears (mean score: ~2.5 to 3.5 out of 12) versus those with mild subacromial bursitis or primary impingement (mean score: ~6.5 to 8.0 out of 12). Furthermore, the scale reliably discriminates between healthy, asymptomatic shoulders (mean scores typically 11.5 to 12.0) and symptomatic cohorts across all age strata.

Responsiveness and Minimal Clinically Important Difference (MCID)

The SST exhibits high responsiveness to clinical change following surgical interventions such as rotator cuff repair, subacromial decompression, and shoulder arthroplasty, with standardized response means (SRM) and effect sizes consistently exceeding $1.0$ (typically $1.20 – 1.85$). Tashjian et al. (2010) established the Minimal Clinically Important Difference (MCID) of the SST in cohorts undergoing rotator cuff repair at 1.5 to 2.4 points (or approximately 12.5% to 20% on the percentage scale). In shoulder arthroplasty populations, an improvement of 2 or more affirmative responses is universally recognized as reflecting a perceptible, clinically meaningful functional gain.

Reliability

The reliability of the Simple Shoulder Test has been confirmed across numerous investigations examining internal consistency, test-retest reproducibility, and measurement error.

Internal Consistency

Because the SST employs dichotomous items, internal consistency is appropriately evaluated using the Kuder-Richardson Formula 20 (KR-20) or standard Cronbach’s alpha. Across published literature, internal consistency estimates consistently meet or exceed the acceptable threshold ($ge 0.80$) for clinical decision-making:

• In the original and subsequent validation cohorts by Matsen and colleagues, KR-20 coefficients ranged from 0.79 to 0.86.
• In the cross-cultural validation of the Dutch SST (van Kampen et al., 2012), Cronbach’s alpha was documented at 0.82 across diverse diagnostic subgroups.
• German, Italian, and Turkish adaptations have yielded alpha coefficients between 0.80 and 0.88, indicating robust item homogeneity without excessive item redundancy.

Test-Retest Reliability

Test-retest stability has been evaluated across intervals ranging from 24 hours to 2 weeks in clinically stable patients prior to operative intervention. The Intraclass Correlation Coefficient (ICC, two-way random effects, absolute agreement) for the overall SST score typically ranges between 0.85 and 0.94:

• Godfrey et al. (2007) reported an ICC of 0.94 (95% CI: 0.90–0.97) among stable pre-operative orthopaedic patients tested 7 to 10 days apart.
• Van Kampen et al. (2012) found an ICC of 0.92 (95% CI: 0.87–0.95) for the total score in their stability analysis.
• Individual item stability evaluated using Cohen’s kappa ($kappa$) ranges from 0.60 to 0.85, reflecting moderate to substantial item-level concordance over time.

Measurement Precision: SEM and MDC

The Standard Error of Measurement (SEM) of the SST is generally estimated between 0.70 and 1.10 points. Consequently, the Minimal Detectable Change at the 90% and 95% confidence intervals ($ ext{MDC}_{90}$ and $ ext{MDC}_{95}$) has been established at approximately 1.6 to 2.2 points. This indicates that a change of 2 or more affirmative responses on the 12-item scale can be attributed to true clinical improvement rather than measurement noise.

Factor Analysis

The structural dimensionality of the Simple Shoulder Test has been evaluated using both Classical Test Theory (Exploratory Factor Analysis [EFA] and Confirmatory Factor Analysis [CFA]) and modern Item Response Theory (Rasch analysis).

Exploratory and Confirmatory Factor Analyses

While designed to generate a single composite score reflecting overall shoulder function, factor analytic studies frequently debate whether the SST is strictly unidimensional or contains two closely interrelated sub-dimensions:

• Unidimensional Model: Multiple studies support an overarching single-factor structure accounting for 45% to 60% of the total variance. In these models, all 12 items load significantly on a primary “Shoulder Disability / Functional Limitation” dimension, with factor loadings ranging from 0.45 to 0.82. Model fit indices in CFA (e.g., Comparative Fit Index $[ ext{CFI}] > 0.92$, Tucker-Lewis Index $[ ext{TLI}] > 0.90$, Root Mean Square Error of Approximation $[ ext{RMSEA}] le 0.07$) support the viability of summing the items into a single composite index.
• Two-Factor Bi-dimensional Model: Alternative factor extractions (using Promax or Oblimin oblique rotations) often yield a two-factor solution:
  1. Factor 1: Basic Functional Activities & Basal Comfort (Items 1, 2, 3, 4, 5, and 11), characterized by low-load movements, reaching, hygiene, and resting comfort.
  2. Factor 2: High-Demand Strength & Ballistic Loading (Items 6, 7, 8, 9, 10, and 12), comprising resisted elevation (1 lb., 8 lbs.), heavy carrying (20 lbs.), throwing tasks, and full-time occupational capacity. The correlation between these two latent factors is typically high ($r > 0.65$), supporting the clinical utility of the composite score.

Rasch and Item Response Theory (IRT) Findings

Rasch measurement models applied to the SST have provided valuable insight into item performance and difficulty calibration:

• Item Infit and Outfit: Rasch analysis indicates that most SST items demonstrate good fit to the measurement model (mean square infit/outfit values between 0.7 and 1.3). Occasional slight outfit underfit has been noted for ballistic items (such as throwing a baseball 20 yards) in elderly populations undergoing reverse total shoulder arthroplasty, where baseline athletic expectations diverge from daily living demands.
• Difficulty Hierarchy: Calibrated item difficulties validate the Guttman-like organization. Item 1 (comfort at rest) and Item 5 (coin on a shoulder-height shelf) display low difficulty thresholds (endorsed by patients even with substantial disability), whereas Item 7 (lifting 8 lbs. to shoulder height) and Item 10 (throwing a baseball 20 yards) present high logit difficulty levels, endorsed primarily by patients who have achieved advanced functional recovery.

Instrument / Measurement Tool

The Simple Shoulder Test is presented as a structured questionnaire designed for rapid administration and unambiguous scoring.

• Assessment Type: Patient-Reported Outcome Measure (PROM); condition-specific functional disability scale.
• Administration Format: Self-administered paper-and-pencil or interactive digital/electronic PROM (e-PROM).
• Target Respondent Population: Adult and geriatric patients (ages 18+) presenting with musculoskeletal conditions affecting the shoulder girdle, including degenerative joint disease, rotator cuff pathology, adhesive capsulitis, proximal humeral fractures, or upper limb trauma.
• Completion Time: Approximately 2 to 3 minutes.
• Total Item Count: 12 discrete, standardized items.
• Response Scale: Dichotomous (Yes / No).
• Scoring Rules:
  • Each affirmative response (“Yes”) indicates functional competence or comfort and is scored as 1 point.
  • Each negative response (“No”) indicates impairment or inability and is scored as 0 points.
  • Raw Sum Score: Calculated by summing the affirmative responses, ranging from 0 (maximal functional limitation / severe disability) to 12 (normal, unrestricted shoulder function and comfort).
  • Percentage Transformation: The raw score is often expressed as a percentage: $\text{SST Score} = \left(\frac{\sum \text{Yes Responses}}{12}\right) \times 100$, producing a standardized range from 0% to 100%.
  • Missing Data Management: If an individual omits 1 or 2 items, standard practice recalculates the score as the percentage of answered items: $\left(\frac{\text{Number of ‘Yes’ Answers}}{\text{Total Number of Answered Items}}\right) \times 100$. If more than 2 items are left blank, the administration is typically invalidated.

Permissions & Fee and Test Year

The Simple Shoulder Test was originally published in 1993 by Steven B. Lippitt, Douglas T. Harryman II, and Frederick A. Matsen III at the University of Washington. Matsen and the University of Washington Shoulder and Elbow Service placed the SST into the public domain to facilitate widespread academic, clinical, and scientific evaluation without licensing friction.

Licensing and Fee Structure:

• Fee: Free of charge ($0.00). There are no licensing fees, royalties, or administrative costs associated with administering the Simple Shoulder Test for clinical care, routine institutional monitoring, or academic research.
• Permissions: Clinicians and researchers are permitted to utilize, reproduce, translate, and digitize the SST provided that proper attribution is given to the original authors and the University of Washington. Alterations to item wording, item order, or response formats are strongly discouraged, as modifications can compromise established psychometric thresholds and comparability across published clinical literature.

References

• Beaton, D., & Richards, R. R. (1996). Measuring function of the shoulder: A cross-sectional evaluation of five rating systems. Journal of Bone and Joint Surgery (American Volume), 78(6), 882–890. https://doi.org/10.2106/00004623-199606000-00011
• Godfrey, J., Hamman, R., Lowenstein, S., Briggs, K., & Kocher, M. (2007). Reliability, validity, and responsiveness of the Simple Shoulder Test: Psychometric properties by disability stage. Journal of Shoulder and Elbow Surgery, 16(3), 260–267. https://doi.org/10.1016/j.jse.2006.07.003
• Lippitt, S. B., Harryman, D. T., II, & Matsen, F. A., III. (1993). A practical tool for evaluating function: The Simple Shoulder Test. In F. A. Matsen III, F. H. Fu, & R. J. Hawkins (Eds.), The Shoulder: A Balance of Mobility and Stability (pp. 501–518). American Academy of Orthopaedic Surgeons.
• Matsen, F. A., III, Antoniou, J., Rozencwaig, R., Campbell, B., & Smith, K. L. (1998). Correlates with comfort and function after total shoulder arthroplasty for degenerative joint disease. Journal of Bone and Joint Surgery (American Volume), 80(7), 1021–1036. https://doi.org/10.2106/00004623-199807000-00011
• Matsen, F. A., III, Ziegler, D. W., & DeBartolo, S. E. (2008). Patient self-assessed outcome measures for the shoulder: Simple Shoulder Test, ASES, and Constant score. In The Shoulder (4th ed., pp. 1325–1340). Saunders/Elsevier.
• Mintken, P. E., Glynn, P., & Cleland, J. A. (2009). Psychometric properties of the shortened Disabilities of the Arm, Shoulder, and Hand questionnaire (QuickDASH) and Numeric Pain Rating Scale in patients with shoulder pain. Journal of Shoulder and Elbow Surgery, 18(6), 920–926. https://doi.org/10.1016/j.jse.2009.03.016
• Roy, J. S., MacDermid, J. C., & Woodhouse, L. J. (2010). Measuring shoulder function: A systematic review of four questionnaires. Arthritis & Rheumatism (Arthritis Care & Research), 62(7), 1024–1034. https://doi.org/10.1002/acr.20163
• Tashjian, R. Z., Deloach, J., Porucznik, C. A., & Powell, A. P. (2010). Minimal clinically important differences (MCID) and return to work rates for the Simple Shoulder Test, American Shoulder and Elbow Surgeons score, and visual analog scale for pain in patients undergoing rotator cuff repair. Journal of Shoulder and Elbow Surgery, 19(4), 589–598. https://doi.org/10.1016/j.jse.2009.10.021
• van Kampen, D. A., van Beers, L. W., Scholtes, V. A., Terwee, C. B., & Willems, W. J. (2012). Validation of the Dutch version of the Simple Shoulder Test. Journal of Shoulder and Elbow Surgery, 21(6), 808–814. https://doi.org/10.1016/j.jse.2011.08.064

Items of the Scale