Fourteen studies were included in the review: three RCTs (84 participants), eight cohort studies (513 participants) and three case-series studies (185 participants).
The scores on the validity assessment scale ranged from 18 to 41 out of a possible 48, with a median score of 22. Five studies were excluded as they did not meet the predefined quality threshold for inclusion.
Immobilisation with general strengthening or stabilisation exercises.
Recurrence of instability: one prospective study reported that recurrence at the 1-year follow-up was 17% for patients immobilised for 3 weeks, compared with 26% for those only immobilised for 1 week. Two small case-series studies reported that 75% and 80% of military personnel managed conservatively had re-dislocated within an average of 36 and 23 months, respectively, compared with only 11% and 14% of surgically treated personnel. A small cohort study reported that 15% of naval academy personnel had re-dislocated at 6 months, while 10% experienced subluxation at 13 and 36 months after 3 weeks' immobilisation followed by restricted activity and a progressive strengthening programme. Another small cohort study reported 92% recurrence among military cadets choosing conservative management, compared with 22% who opted for surgical intervention; there were statistically significantly fewer recurrences of instability when rehabilitation commenced after surgery. A small RCT reported 47% recurrence at the 2-year follow-up after 3 weeks' immobilisation followed by a 12-week range-of-motion and strengthening programme, and 16% recurrence in patients who had stabilisation surgery prior to the same immobilisation and rehabilitation programme; this difference was statistically significant.
Return to pre-morbid status: three studies of military and naval academy personnel reported that patients returned to full active duty at 4 months, after 3 weeks' immobilisation followed by progressive strengthening. However, in two studies that asked patients to rate their overall outcomes, conservatively managed patients rated their overall outcomes significantly worse than those in a surgical comparison group. An additional study compared immobilisation for 1 week with immobilisation for 3 weeks and found statistically significantly less weeks lost from work during rehabilitation for those immobilised for 1 week; however, the functional outcomes for these patients were significantly poorer.
Disease-specific quality of life: a small RCT reported poorer quality-of-life scores in patients who underwent 3 weeks' immobilisation followed by a 12-week range-of-motion and strengthening programme than in patients who had stabilisation surgery prior to the same immobilisation and rehabilitation programme.
Stabilisation exercises alone.
Recurrence of instability: two poor-quality studies reported poor outcomes and high recurrence rates in patients given only stabilisation exercises.
Return of symptoms: a poor-quality cohort study reported that progressive strengthening of the rotator cuff muscles decreased reports of pain and instability in 77% patients with moderate disability secondary to posterior shoulder instability. However, more severely disabled patients did not have such a high rate of improvement. In a small RCT, 68% of conservatively managed patients reported improvement at 4.8 years after conservative management, compared with 52% patients who underwent surgical intervention after conservative management failed.
Multimodal intervention or undefined protocol.
Recurrence of instability: in a poor-quality cohort study, 16% patients being managed with a multimodal approach reported either dislocation or subluxation within 3.7 years' follow-up, compared with 41% of patients who had undergone previous surgery; this difference was statistically significant. A higher quality cohort study reported that 60% of conservatively managed patients had re-dislocated at 2 years' follow-up, compared with 20% patients managed surgically; this difference was statistically significant.
Return to pre-morbid status: a prospective cohort study reported statistically significantly improved outcomes after conservative management using proprioceptive neuromuscular facilitation (PNF) patterning, biofeedback and strengthening exercises for patients who had not previously undergone shoulder surgery versus those who had undergone prior shoulder surgery. Another cohort study reported no statistically significant differences in outcomes measured between patients who received surgical treatment and those who received conservative management.
Return of symptoms: a prospective cohort study reported statistically significantly improved outcomes, in terms of the severity or prevention of return of symptoms after conservative management using PNF patterning, biofeedback and strengthening exercises, for patients who had not previously undergone shoulder surgery versus those who had undergone prior shoulder surgery.
Electromyography (EMG) biofeedback.
Return to pre-morbid status and return of symptoms: a small RCT reported statistically significantly improved function at work and in sport at 8 and 52 weeks for patients given visual and auditory EMG feedback of rotator cuff muscle contraction during a functional endurance programme twice weekly than patients given an isokinetic resistance exercise programme of the same frequency. The RCT also reported statistically significantly decreased pain at rest and with activity at 26 and 52 weeks' follow-up for the EMG feedback group compared with baseline scores. The isokinetic exercise group showed no significant change at any time during follow-up.