{"id":2045,"date":"2026-09-12T06:27:25","date_gmt":"2026-09-12T06:27:25","guid":{"rendered":"http:\/\/ashadocs.org\/scales\/karlsson-ankle-function-score\/"},"modified":"2026-09-12T06:27:25","modified_gmt":"2026-09-12T06:27:25","slug":"karlsson-ankle-function-score","status":"publish","type":"psych_scale","link":"https:\/\/ashadocs.org\/?psych_scale=karlsson-ankle-function-score","title":{"rendered":"Karlsson Ankle Function Score"},"content":{"rendered":"

Abstract<\/h2>\n

The Karlsson Ankle Function Score<\/strong> (often abbreviated as the KAFS or simply the Karlsson Score) is an established clinician-administered and patient-reported outcome measure developed by J\u00f3n Karlsson and colleagues in 1991. Designed initially to assess functional outcomes following surgical reconstruction and conservative rehabilitation of chronic lateral ankle ligament instability, the instrument has achieved widespread clinical and psychometric prominence in orthopaedic surgery, sports medicine, and physical therapy. The Karlsson Score quantifies subjective and objective dimensions of ankle impairment into an aggregated metric ranging from 0 to 100 points, where higher point values signify superior functional capacity and negligible impairment. The scale comprises eight discrete functional categories: pain (20 points), swelling (10 points), subjective instability or giving way (15 points), joint stiffness (5 points), stair climbing ability (10 points), running capacity (10 points), occupational and activities of daily living performance (15 points), and dependency on external structural support such as taping or bracing (15 points). Psychometric investigations demonstrate that the Karlsson Ankle Function Score possesses strong construct, convergent, and discriminant validity, exhibiting high correlation with alternative extremity instruments such as the Foot and Ankle Outcome Score (FAOS), the American Orthopaedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot Scale, and the Tegner Activity Score. Reliability analyses across international adaptations confirm robust internal consistency (Cronbach’s alpha typically exceeding 0.80) and excellent test-retest stability (intraclass correlation coefficients generally between 0.85 and 0.96). Responsiveness indices, including the standardized response mean and effect size, indicate that the scale sensitively registers clinically meaningful post-intervention changes following ligament repair, arthroscopic stabilization, and structured neuromuscular training.<\/p>\n

Keywords<\/h2>\n

Karlsson Ankle Function Score, chronic ankle instability, lateral ligament reconstruction, patient-reported outcome measures, orthopaedic assessment, foot and ankle surgery, psychometrics, joint stability, functional impairment, rehabilitation outcomes<\/p>\n

Authors<\/h2>\n

The primary author and developer of the instrument is J\u00f3n Karlsson, MD, PhD<\/strong>, Senior Professor of Orthopaedics and Sports Traumatology at the Department of Orthopaedics, Sahlgrenska University Hospital and the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. Dr. Karlsson has served extensively as Editor-in-Chief of Knee Surgery, Sports Traumatology, Arthroscopy<\/em> (KSSTA) and has contributed foundational clinical trials regarding ankle ligament trauma, biomechanics, and long-term joint survivorship. Co-investigators on the foundational development papers included surgical colleagues and clinical researchers affiliated with the Department of Orthopaedics at East Hospital (\u00d6stra Sjukhuset) in Gothenburg, Sweden.<\/p>\n

Purpose<\/h2>\n

The Karlsson Ankle Function Score was conceived to solve a critical methodological deficit in clinical orthopaedics: the absence of a standardized, sensitive, and reproducible system to quantify functional recovery following lateral ankle ligament injuries and reconstructive procedures. While classical physical examinations assess objective mechanical laxity through anterior drawer and talar tilt stress radiography, objective mechanical stability frequently correlates poorly with patient-perceived functional stability, subjective apprehension, and dynamic return to athletic or occupational performance. Therefore, the primary purpose of the Karlsson Score is to provide a standardized, clinically tractable evaluation tool that captures both subjective symptomatology (e.g., pain, stiffness, sensation of giving way) and objective functional capacity (e.g., stair navigation, running, occupational exertion, requirement of external orthoses).<\/p>\n

In clinical practice, the tool serves as a routine monitoring instrument administered preoperatively, postoperatively, and during longitudinal outpatient rehabilitation. It enables orthopaedic surgeons, sports physicians, and physical therapists to track recovery trajectories, identify persistent deficits, calibrate progression through return-to-sport protocols, and determine whether surgical interventions such as the modified Brostr\u00f6m-Gould procedure, anatomical ligament reconstruction, or arthroscopic repairs have restored functional joint mechanics. In clinical research, the Karlsson Score serves as a standardized primary or secondary endpoint in randomized controlled trials, prospective cohort studies, and systematic meta-analyses comparing surgical techniques, conservative neuromuscular training regimens, and rehabilitation timelines.<\/p>\n

The theoretical rationale rests upon the modern biopsychosocial and functional definitions of impairment. An isolated measurement of ligamentous mechanical tensile strength does not account for neuromuscular control, proprioceptive deficits, compensatory movement strategies, or fear-avoidance behaviors that develop following joint injury. By integrating self-reported physical impairments, activity limitations, and compensatory reliance on external stabilization, the Karlsson Ankle Function Score translates multi-faceted joint pathology into an interpretable metric that facilitates direct comparison across clinical cohorts.<\/p>\n

Psychological Construct<\/h2>\n

Although initially developed in an orthopaedic surgical framework, the Karlsson Ankle Function Score operationalizes a multi-dimensional construct encompassing physical impairment, functional disability, and the behavioral adjustments stemming from perceived joint vulnerability. The overarching construct can be designated as perceived functional ankle competence<\/em>, which is comprised of several interacting physical and behavioral dimensions:<\/p>\n