Aims To explore the ability of a physiotherapist, using a standardised musculoskeletal physiotherapy assessment protocol, to accurately identify the structures potentially responsible for shoulder symptoms against a standardised arthroscopic shoulder diagnostic assessment, and to determine the physiotherapists’ ability to influence post-test diagnostic accuracy.

Study design Consecutive case-based cohort study.

Subject selection All participants were selected by two orthopaedic surgeons for arthroscopic investigation during a 6-month period.

Setting Private orthopaedic clinic.

Method All consenting participants selected for arthroscopic investigation were examined by the physiotherapist prior to arthroscopy. Presence and priority of impairments/diagnoses were recorded on a standardised form. Inter and intra-rater reliability and diagnostic accuracy were tabulated.

Statistical analysis Proportional agreement on diagnostic incidence (broad) and priority (strict) using 2×2 contingency tables for sensitivity, specificity, positive and negative predictive value and positive and negative likelihood ratios were calculated. Post-test probabilities were analysed to determine the influence of a positive or a negative finding.

Results 211 participants, aged 14–79 years were included. Overall prevalence of subacromial pathology was (77%) and, disorders of the passive restraints (29%). For both negative and positive findings, post-test probabilities were not notably altered; although positive findings yielded greater value in the decision-making modelling. The physiotherapist's ability to identify individual pathology (eg, tendon rupture vs tendinopathy, capsular vs labral) was lower than recognition of pathology within the broader diagnostic category.

Conclusions The physiotherapist's ability to diagnose individual pathologies was inconsistent. Indirectly, this raises the issue of whether signs and symptoms identified under arthroscopic surgery are reflective of a lesion/pathology reflective of a specific tissue.