Prevalence and Risk Factors of Neuropathic Pain in Patients with a Rotator Cuff Tear.

BACKGROUND: Until now, few studies had investigated the neuropathic pain component in patients with a rotator cuff tear (RCT).

OBJECTIVES: The aim of the study was to identify the neuropathic pain component in patients with RCT and to determine the factors correlated with neuropathic pain in patients with RCT.

STUDY DESIGN: Prospective, cohort, prognostic study.

SETTING: Study patients who required arthroscopic rotator cuff repair were analyzed in a hospital setting.

METHODS: We prospectively studied 101 patients who were less than 60 years old with full-thickness tears requiring arthroscopic rotator cuff repair and met the inclusion and exclusion criteria. Multiple regression analysis was performed to identify variables that independently affected neuropathic pain in patients with a RCT. We use Douleur neuropathique 4 questionnaire (DN4) to assess neuropathic pain, which was >/= 4 points of the DN4 questionaire. The visual analog scale (VAS) for the most severe pain within 4 weeks before admission and mean pain level during the last 4 weeks were checked. The atrophy grades of the rotator cuff muscles were classified on magnetic resonance images according to the Goutallier classification. The size and medial retraction of the RCT were measured during arthroscopic repair for RCT.

RESULTS: Sixteen (15.8%) of the 101 patients had neuropathic pain according to the cut-off values on the DN4 questionnaire for diagnosing neuropathic pain. The neuropathic pain group had significantly higher prevalence of smoking (P = 0.042), more mean VAS during last 4 weeks (P = 0.008), larger cuff tear (P = 0.003), more medial retraction of cuff (P = 0.016), and severe fatty degeneration of rotator cuff muscles (supraspinatus, P < 0.001; subscapularis, P < 0.001; and infraspinatus, P = 0.003) than the nonneuropathic pain group. The multiple logistic regression analyses showed that more mean VAS during the last 4 weeks and tear size of a rotator cuff were independent of other factors for the neuropathic pain of the patients with a full-thickness RCT.

LIMITATIONS: Small sample size is the first limitation of this study.

CONCLUSIONS: The prevalence of neuropathic pain in patients with a full-thickness RCT requiring arthroscopic rotator cuff repair was 15.8 % according to the DN4 questionnaire. The neuropathic pain component was more relevant to the severity of pain and tear size in the patients with a full-thickness RCT. It is important to be aware of the existence of neuropathic pain when treating a patient presenting with pain due to a RCT because accompanying neuropathy with a RCT could have a worse effect on repair of a RCT. IRB approval and clinical trial registration number: CR-15-045.

KEY WORDS: Shoulder, rotator cuff tear, arthroscopic rotator cuff repair, neuropathic pain.