Glenohumeral joint instability in the athlete encompasses a wide spectrum of pathology with extreme cases presenting as glenohumeral dislocation. Treatment options begin with glenohumeral reduction followed by nonoperative and/or operative intervention. The purpose of this article is to review the best available evidence for treatment of acute shoulder dislocations in the athlete with specific attention directed towards reduction techniques and the decision for nonoperative versus operative treatment.
Glenohumeral instability occurs across a wide range of activities and age groups. The reported incidence of acute traumatic glenohumeral instability ranges from 8.2/100,000 person-years to 23.9/100,000 person-years in the general population with an estimated prevalence of 1.7% (1-3). These estimates are based upon patients presenting to medical care facilities and likely are under-representative of the true values as many patients with subluxation events do not seek medical care. These studies also include the general population, encompassing all age groups, making extrapolation to younger athletes unreliable. In a descriptive epidemiologic study of United States Military Academy cadets over the course of one academic year (4), the incidence rate of new traumatic shoulder instability events was 2.8%, with 84.6% of events classified as subluxations. In this study, 43.6% of events occurred as a result of contact injuries.
INITIAL EVALUATION AND TREATMENT
An athlete with an acutely dislocated shoulder requires urgent management. A short history should include information regarding recurrence (is this the patient's first dislocation?), and severity of the injury. First dislocations with extremely high energy trauma in older individuals may be associated with fractures, which could displace if not recognized before attempts at reduction. In addition, because significant axillary nerve injuries can occur in up to 12.5% of dislocations (5), assessing sensation on the lateral arm may help identify this injury before reduction attempts are made, clarifying the cause and preventing the misconception that the nerve injury might be iatrogenic.
PREMEDICATION FOR SHOULDER REDUCTION
On the sideline, if recognized early before muscle spasm develops, a dislocated shoulder can be reduced without any premedication. Failed attempts or situations where the athlete has increased pain and spasm may require premedication. A recent systematic review of Level 1 evidence compares intra-articular lidocaine with intravenous sedation for shoulder reductions in the emergency department setting (6). This review concludes that success rates are similar, and intra-articular lidocaine has fewer complications with less time required for discharge from the emergency department.
SHOULDER REDUCTION TECHNIQUES
A review of published literature reveals more than 24 described techniques for reducing an acute glenohumeral dislocation (7). Success rates for each individual technique vary widely from author to author, and closer analysis reveals that most of the studies are subject to a high degree of performance bias because of inclusion of different patient populations, associated fractures, recurrent dislocations, inconsistent premedication regimens, and varying levels of clinician experience. These factors along with modifications to originally described techniques place these studies low on the evidence-based medicine (EBM) hierarchy (EBM Levels IV and V) and make comparisons difficult. One randomized controlled trial does exist comparing the modified Kocher and Milch techniques (8) (EBM Level I). No statistically significant differences in the success rates for the two techniques were detected. Higher success rates of reduction were noted in patients younger than 40 yr, compared with those older than 40 yr and in patients of slight build compared with those of heavier build.
In summary, many described techniques exist for reducing an acute glenohumeral dislocation, but no specific recommendations can be made because of a lack of high quality studies comparing the various techniques. The treating clinician should learn two to three techniques and gain experience with each.
ASSESSMENT OF THE ATHLETE WITH A REDUCED SHOULDER DISLOCATION
The evaluation and management of the athlete who reports to the training room or clinic with a reduced shoulder dislocation is highly individualized. The goals of treatment are to prevent recurrence, and return the athlete to sport as quickly and safely as possible. Unfortunately, there are no clinical pathways to date to help the clinician make decisions. As such the evaluation must include information to help the treating physician provide guidance to the athlete to help him or her make decisions.
A thorough history and physical examination serve as the cornerstone upon which diagnosis and treatment decisions are based. A variety of historical features may help in the decision whether or not surgical treatment may be recommended. In multiple studies of various quality, younger age seems to stand out as a predictor of recurrence. Patients under the age of 30 yr had recurrence rates of 50%-64% (9-11). While it would seem that participation in athletics would increase recurrence, the data for this as a risk factor are mixed, with some studies suggesting no relationship (9,12), and others demonstrating a relationship exists (10). High energy level of the trauma likely has a role in recurrence of instability (13). Another important aspect of the history is the spectrum of severity of the instability event. A spontaneous reduction suggests a less severe injury than a dislocation that required assistance to reduce. More severe injuries likely cause more damage to the labrum and capsule possibly leading to a higher risk of recurrence. At this point, we do not have great data on these and other historical features, limiting our ability to predict the risk of recurrence. Also of importance is the timing of the dislocation with respect to the player's season. If the first dislocation occurs early in the player's season, it is likely he or she would be more interested in returning to play, as opposed to having surgery and missing the remainder of the season.
Physical exam begins with visual inspection of bilateral shoulders looking for evidence of asymmetry in bony or muscular contour. Palpation should include bony prominences as well as the anterior and posterior joint lines. Range of motion and muscle strength should be documented with the contralateral shoulder used for comparison. Particular attention should be directed toward the function of the axillary nerve and the rotator cuff, particularly in older athletes.
Imaging studies are helpful and include radiographs, computed tomography (CT) scans, and magnetic resonance imaging (MRI). Radiographs should include anterior-posterior, scapular-Y, and axillary views. From these images, joint reduction can be determined, as well as associated fractures or bony anatomical variants. A CT scan is useful for preoperative evaluation if questions exist regarding the integrity of bony structures and can demonstrate articular version, associated fracture patterns, and potential bone loss that may add to the complexity of future surgical procedures. In patients with obvious history and classic physical exam findings, an MRI is not routinely necessary, but should be obtained in the setting of a vague history or unclear physical exam. MRI is useful for evaluating soft-tissue structures such as the labral complex and rotator cuff and should be evaluated for the presence of bone edema and/or the presence of a Hill-Sachs lesion. Often an arthrogram is not necessary in the setting of acute instability due to the presence of effusion within the joint. One would expect that bony injury would increase the risk of recurrence; however, the data in the literature are mixed, with most studies suggesting Hill-Sachs lesions do not influence recurrence (9,11,12,14). However, some studies suggest otherwise (15-18). Similar results have been reported for the presence of a bony Bankart lesion (9,11,12,14,19); however, Robinson reports a bony Bankart lesion is associated with a relative risk of 7.0 for recurrence (13).
TREATMENT OF THE ATHLETE WITH A REDUCED SHOULDER DISLOCATION
A review of the existing literature regarding nonoperative treatment of shoulder dislocations reveals over 190 potential manuscripts of which seven studies meet EBM Level I or II criteria (15-18,20-22). This article will focus upon these aforementioned studies in order to present the best available evidence for clinical decision-making (Table 1).
Hovelius et al. (15-18) (EBM Level I) presents four studies following the same prospective cohort of 257 patients presenting with primary anterior shoulder dislocations at intervals of 2, 5, 10, and 25 yr. Patients were randomized into one of two treatment groups: immobilization in internal rotation for 3-4 wk or use of a sling, which was discontinued when the patient was comfortable. The primary outcome measure was recurrence rate, and final analysis reveals no statistically significant differences between the two groups at any time point. It is interesting to note that recurrence increased up to 5 yr, at which point it leveled off, with approximately half of the patients having at least one recurrent episode of instability
Kiviluoto et al. (20) (EBM Level II) followed a prospective cohort of 226 patients over a 1-yr period with recurrence as the primary outcome measure. All patients over the age of 50 yr (N = 127) and 53 patients under the age of 50 yr were treated with 1 wk of immobilization in internal rotation. The remaining 46 patients under the age of 50 yr were immobilized with a stockinette-Gilchrist bandage for 3 wk. Randomization methods for the patients under the age of 50 yr were not specified. A recurrence rate of 8% was found in the patients over the age of 50 yr, and recurrence rates in the patients younger than the age of 50 yr were not statistically significant (26% in the short duration of immobilization group vs 17% in the longer duration of immobilization group). The authors performed a post hoc analysis for patients under the age of 30 yr, revealing a higher frequency of redislocation in this subset of patients compared with the older subset, as well as a statistically significant increase in frequency of recurrence in the shorter duration of immobilization group compared with the longer duration group (50% vs 22%, P < 0.05). Care must be taken when extrapolating these results to clinical practice because of the inherent bias introduced with post hoc analysis.
Itoi et al. (21,22) (EBM Level II) followed an initial prospective cohort of 198 patients for a minimum of 2 yr. Study participants were randomized into one of two treatment groups: immobilization in internal rotation with a sling and swathe for 3 wk or immobilization in adduction and 10° external rotation for 3 wk. The primary outcome measure was recurrence, and 80% of those initially enrolled were available for follow up at a minimum of 2 yr. Subjective evaluation of compliance rate revealed values of 53% in the internal rotation group and 72% in the external rotation group (P = 0.013). Using an intention-to-treat analysis, the authors found a statistically significant difference in recurrence comparing the internal rotation group to the external rotation group (42% vs 26%, P = 0.033) with a relative risk reduction of 38.2%. Limitations of the study include the statistically significant difference in subjective compliance rates among the two groups, failure to use blinded, independent examiners, and lack of patient-validated outcome assessments.
Return to Play
There are little data on when is it safe for an athlete to return to the field after sustaining a dislocation. Most authors recommend waiting until the athlete has a full range of motion and strength and can participate in sport activities (23). Buss et al. (24) followed 30 athletes with instability who returned to play. In this group, 37% had at least one episode during their season.
To summarize, the highest available evidence for the nonoperative treatment of a first shoulder dislocation suggests the following: 1) overall the recurrence rate is approximately 50%, 2) immobilization in internal rotation does not affect the recurrence rate and should be used for the patient's comfort, and 3) immobilization for 3 wk in external rotation likely decreases recurrence when compared with immobilization in internal rotation, but further well-designed studies are needed before a definitive conclusion can be reached.
Does surgery reduce recurrence of instability compared with nonoperative treatment? Four well-designed, randomized, controlled trials comparing operative with nonoperative treatment for traumatic anterior dislocations have been published (25-30) (Table 2). Bottoni et al. (25) (EBM Level I) randomized young, active-duty military personnel with primary, traumatic dislocations to either immobilization in a sling for 4 wk or arthroscopic repair with a bioabsorbable tack followed by the same rehabilitation protocol for each group. With 88% follow-up at an average of 3 yr, recurrent instability was noted in 11.1% of the arthroscopic group versus 75% of the nonoperative group. Statistical comparison was not performed.
Kirkley et al. (26) (EBM Level I) randomly allocated patients younger than 30 yrs with a first, traumatic anterior dislocation to immobilization for 3 wk or arthroscopic stabilization followed by immobilization for 3 wk. The rehabilitation protocols were the same in each group, and follow-up was 95% at a mean of 32 months. Recurrent instability occurred in 15.9% of the arthroscopic patients versus 47% of the nonoperative patients (P = 0.03). Analysis of disease-specific quality of life indices using the validated Western Ontario Shoulder Instability (WOSI) index revealed scores in the surgical group that were 16.5% better than scores in the nonoperative group (P = 0.03). Kirkley et al. (27) (EBM Level II) further published results using the same subjects with 78% follow-up at an average of 79 months. Using the intention-to-treat analysis (7/15 initial nonoperative patients underwent surgery), WOSI scores in the surgical group were 11% better than scores in the nonoperative group (P = 0.17). No further instability episodes occurred in either group.
Arthroscopic lavage after traumatic dislocation has been shown to decrease the duration of joint effusion, possibly aiding in the healing of capsulolabral structures (28). Wintzell et al. (29) (EBM Level I) randomized primary, traumatic anterior dislocation subjects to arthroscopic lavage at an average of 7 d post-injury or no surgery. All patients were given an optional sling to be used for the first week and were encouraged to move the affected shoulder. With 100% follow-up at 24 months, recurrent instability was noted in 20% of the lavage group compared with 60% of the non-surgical group (P = 0.03). Constant-Murley scores and Rowe shoulder scores were not statistically significant between the two groups.
Jakobsen et al. (30) (EBM Level I) performed diagnostic arthroscopy on primary anterior dislocation patients followed by randomization into either open repair with suture anchors or immobilization in a sling for 2 d followed by the same rehabilitation protocol for each group. With 95% follow-up at 2 yr, recurrent dislocation was noted in 2.7% of the open repair patients compared with 53.8% of the immobilization patients (P = 0.0011). With 94% follow-up at 10 yr, recurrent dislocation was noted in 9% of the open repair patients compared with 62% of the immobilization patients. Statistical significance was not assessed for the data at 10-yr follow-up.
These data clearly demonstrate that surgery reduces recurrence, yet which surgical technique is best? Review of the literature concerning the best form of operative treatment can be confusing. Open Bankart repairs have been performed since the 1930s (31), and arthroscopic techniques have been used since the early 1990s. At least four meta-analyses based upon literature reviews have been published comparing arthroscopic to open repair (32-35). Agreement exists demonstrating higher recurrence rates with arthroscopic repair using transglenoid sutures or staples compared with historic open repair controls, but direct comparisons amongst these manuscripts cannot be accurately performed because of inconsistent methodology rating systems, differing patient populations (first-time vs recurrent instability), and inclusion of varying levels of evidence (EBM Levels I-IV).
Advancements in suture anchor technology have improved outcomes after arthroscopic repair as displayed with review of two randomized controlled trials (36,37) comparing arthroscopic repair with suture anchors to open repair with suture anchors. Fabbriciani et al. (36) (EBM Level I) randomly allocated 60 patients with isolated Bankart lesions confirmed arthroscopically to operative repair with metallic anchors using open or arthroscopic technique. At an average of 2 yr after surgery, no statistically significant differences were found between the two groups for recurrence (no recurrences noted in either group). Significantly greater postoperative range of motion evaluation with the constant score was noted in the arthroscopic group compared with the open group (mean value of 39.6 vs 37.8, P = 0.017). Care should be taken when interpreting the latter finding because of a lack of objective range of motion evaluation in the study. Sperber et al. (37) (EBM Level I) performed a multicenter study involving seven surgeons in which 56 patients with arthroscopically verified Bankart lesions were randomly allocated to arthroscopic repair with bioabsorbable anchors or open repair with metallic anchors. The 2-yr results revealed no statistically significant difference in recurrence between the groups (23% in the arthroscopic group, 12% in the open group, P = 0.65). Care should be taken when applying the results of the above studies to clinical practice because of study exclusion of patients with associated glenohumeral pathology and Bankart lesions involving more than 5 mm of bone.
To summarize the highest available evidence, open or arthroscopic repair of a primary, traumatic dislocation results in a statistically significant reduction in recurrence when compared with nonoperative treatment. In addition, arthroscopic repair using suture anchors has postoperative recurrence rates similar to open repair in treatment of isolated Bankart lesions. Recurrence after arthroscopic repair using transglenoid sutures or staples is less favorable compared with open repair.
Glenohumeral instability is a relatively common clinical problem requiring systematic evaluation of each presenting patient and familiarity with several methods of reduction. Using an evidence-based approach to the patient with a primary dislocation, one can conclude the following: 1) there is little quality evidence to advocate one reduction technique over another, 2) premedication with intra-articular lidocaine is preferred over intravenous narcotics and benzodiazepine, 3) recurrence rates are age-related and may be associated with higher energy injuries, but other predictors of recurrence are not clear, 4) post-reduction immobilization in internal rotation does not affect recurrence, 5) post-reduction immobilization in external rotation appears to decrease recurrence, 6) recurrence after arthroscopic repair using transglenoid sutures or staples is higher compared with open repair, 7) recurrence after arthroscopic repair with suture anchors is comparable with open repair, and 8) arthroscopic or open repair decreases recurrence compared with arthroscopic lavage alone or nonoperative treatment. Further research is needed to clarify risk factors that predict recurrence in order to assist the clinician in deciding upon operative versus nonoperative treatment. Until then, the decision to proceed with surgery for a first-time dislocation is dependent upon speculative risks for recurrence, the timing of the athlete's seasons, and the desires of the patient.
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