| ORIGINAL ARTICLE |
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| Year : 2016 | Volume
: 2
| Issue : 2 | Page : 86-93 |
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Validation of a modified Scoliosis Research Society instrument for patients with limb deformity: The limb deformity-Scoliosis Research Society (LD-SRS) score
Peter D Fabricant1, Eugene W Borst2, Stuart A Green3, Robert G Marx4, Austin T Fragomen2, S Robert Rozbruch2
1 Pediatric Orthopaedic Surgery Service, Hospital for Special Surgery, New York, USA
2 Limb Lengthening and Complex Reconstruction Service, Hospital for Special Surgery, New York, NY, USA
3 Department of Orthopaedic Surgery, University of California-Irvine, Orange, CA, USA
4 Sports Medicine and Shoulder Service, Hospital for Special Surgery, New York, NY, USA
Correspondence Address:
Peter D Fabricant
Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021
USA
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/2455-3719.190710
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Background: Despite the large negative effect of limb deformity on health-related quality of life (QoL), there exists no patient-reported instrument to quantify this impact. Rather, limb deformity research has been performed using global QoL measurements concurrently with joint-specific and/or arthritis outcome scales, thereby requiring the completion of multiple instruments. Furthermore, joint- and arthritis-specific instruments focus on the impact pain has on function, whereas limb deformities may be pain-free with greater social and functional impairment. The purpose of this study was to validate a patient-reported instrument to quantify limb deformity-related QoL.
Materials and Methods: Because of the similarities with regard to pain, function, and body image between limb deformity and scoliosis, the Scoliosis Research Society-30 (SRS-30) spine deformity instrument was modified such that the words "back" and "trunk" were replaced with "limb" to create a novel instrument: the limb deformity-SRS (LD-SRS). Testing for construct validity (both convergent and discriminant), reliability, floor and ceiling effects, and minimal clinically important difference (MCID) was performed in a validation cohort of 62 subjects aged 18 years or older with nonarthritic, unilateral lower extremity deformity.
Results: Scale reliability was excellent (test-retest reliability, intraclass correlation coefficient = 0.977; internal consistency, Cronbach's alpha = 0.906), scores were normally distributed, and there were no floor or ceiling effects. There was also robust construct validity: convergent validity testing revealed positive correlations between the LD-SRS and all short-form-36 domains, the American Academy of Orthopaedic Surgeons-Lower Limb Module, and higher scores in those who were postcorrection. Discriminant validity was demonstrated with no correlations between the LD-SRS and subject age, sex, body mass index, surgeon-scored Limb Lengthening and Reconstruction Society-AIM Index, or surgeon-generated deformity measurements. MCID was calculated to be 0.3 (on a 4.0-point scale).
Conclusions: The LD-SRS score is a reliable and valid instrument to measure limb deformity-related QoL in patients with nonarthritic lower extremity deformity. It is a valuable tool which allows clinicians to quantify patients' deformity-related QoL with a single instrument, rather than repurposing scales which have been validated for other conditions and have limited applicability to the unique challenges of treating patients with a lower limb deformity.
Level of Evidence: Diagnostic, Level 2.
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