Our objective was to determine the plasma levels of substance P (SP) in patients with postoperative stiffness after arthroscopic rotator cuff repair.

Plasma samples were obtained at 15 months from surgery from 2 groups of patients who underwent arthroscopic repair of a rotator cuff tear. In Group 1, 30 subjects (14 men and 16 women, mean age: 64.6 years, range 47 to 78) with shoulder stiffness 15 months after arthroscopic rotator cuff repair were recruited. In Group 2, 30 patients (11 men and 19 women, mean age: 57.8 years, range 45 to 77) were evaluated 15 months after successful arthroscopic rotator cuff repair. Immunoassays were performed with commercially available assay kits to detect the plasma levels of SP.

The mean plasma levels of SP in patients with postoperative stiffness were significantly greater than those in the control group (81.06 ± 27.76 versus 23.49 ± 5.64, P < 0.05).

The plasma concentrations of substance P in patients with shoulder stiffness after arthroscopic rotator cuff repair are higher compared to plasma levels of SP in patients with a good postoperative outcome. The neuronal upregulation of SP shown in the plasma of patients with post operative shoulder stiffness may underlay not only the symptoms of adhesive capsulitis, but also its development.

Postoperative stiffness (POS) of the shoulder may occur after an apparently successful reconstruction of a rotator cuff tear.

The role of the peripheral nervous system in tissue healing has only recently been recognized.

We determined the plasma levels of SP in patients with postoperative stiffness after arthroscopic repair of a rotator cuff tear, and compared them with those in patients with a good outcome after arthroscopic rotator cuff repair.

Plasma samples were obtained at 15 months from surgery from 2 groups of patients who underwent arthroscopic repair of a rotator cuff tear. In Group 1, 30 subjects (14 men and 16 women, mean age: 64.6 years, range 47 to 78) with shoulder stiffness 15 months after arthroscopic rotator cuff repair were recruited. In Group 2, 30 patients (11 men and 19 women, mean age: 57.8 years, range 45 to 77) were evaluated 15 months after successful arthroscopic rotator cuff repair. Immunoassays were performed with commercially available assay kits to detect the plasma levels of SP.

Statistical analysis were performed with Wilcoxon Sign Rank test. Significance was set at P< 0.05

The concentrations of the neuropeptide SP in sera were measurable in all patients. Patients with postoperative stiffness had statistically significant greater plasma levels of SP than patients in whom arthroscopic repair of rotator cuff tears had resulted in a good outcome (P < 0.05)

Postoperative stiffness (POS) of the shoulder may occur after an apparently successful reconstruction of a rotator cuff tear.

An increased amount of SP in the subacromial bursa has been correlated with the pain caused by rotator cuff disease.

SP stimulates DNA synthesis in fibroblasts, which are the cellular components of the adhesive capsulitis of the shoulder. Also, SP is a pain transmitter peptide, and pain may cause a secondary muscular and/or capsular contracture.

Our results show that the plasma concentrations of substance P in patients with shoulder stiffness after arthroscopic rotator cuff repair are higher compared to plasma levels of SP in patients with a good postoperative outcome.

We cannot determine the cause of POS in our patients, but the findings of this study suggest a possible neuronal role in the pathophysiology of POS after arthroscopic repair of rotator cuff tears. The knowledge of the pathophysiological role of sensory nerve peptides in tissue repair in these patients could open new therapeutic options to manage conditions of the musculo-skeletal system with impaired tissue-nervous system interaction.