Tracey Didinger, MD; Jennifer Reed, NP; and Eric McCarty, MD
Posterior shoulder instability, in comparison to anterior instability, is relatively uncommon. Posterior instability represents 2% to 10% of shoulder instability.1–3 Hawkins emphasized the difference between recurrent posterior dislocations and subluxations.4 Athletes often sustain traumatic posterior shoulder dislocations as a result of a direct blow to the anterior shoulder with the arm flexed, adducted, and internally rotated. Athletes may also have generalized ligamentous laxity which contributes to repetitive microtrauma causing recurrent posterior subluxations (RPS). RPS can be seen in overhead athletes, swimmers, weightlifters, football lineman, tennis players, and others.5,6
Along with performing a thorough history and physical exam, physicians should maintain a high index of suspicion when evaluating patients for posterior instability. Patients often report pain with the shoulder in provocative positions including forward flexion, adduction, and internal rotation.7 As shown by Pollock and Bigliani,8 two-thirds of athletes who ultimately required surgery presented with symptoms using their shoulder outside of sport, particularly when above shoulder height. Ultimately it is important to understand the athlete’s sport, position, future goals, and requirements when considering his or her post-surgical rehabilitation and return to play.
Greater details of treatment for posterior instability was discussed in Chapters 19 and 20; however, numerous authors recommend a trial of conservative management for nontraumatic posterior instability.4 This includes at least 6 months of physical therapy focusing on shoulder range of motion (ROM) and increasing the strength and control of the dynamic shoulder stabilizers.9 Surgical intervention is often required particularly in athletes that sustained a traumatic posterior dislocation.
This chapter will focus on a series of phases in the rehabilitation following posterior stabilization with the goal of return to play, keeping in mind these phases should not be approached strictly sequentially as there is overlap throughout. The importance of a team approach among the surgeon, athlete, and physical therapist cannot be overemphasized. Throughout the initial phases of recovery there is an intricate balance between immobilization to allow the repair to heal and mobility to prevent stiffness and muscle shutdown. Rehabilitation progresses over approximately six to nine months to include increasing ROM, strengthening, and ultimately sport-specific programs. Goals for an athlete should mirror an ability to first gain sport-specific skills and ability to perform, followed by practice in controlled situations, and finally return to play in competition.
POSTERIOR STABILIZATION REHABILITATION
Phase I: 0 to 2 Weeks
The initial goals following surgery include healing of the incisions, managing pain and inflammation, protecting the repaired structures, and minimizing the effects of immobilization.
Following arthroscopic or open posterior stabilization patients should be placed in a sling using an abduction pillow in neutral or slight external rotation (ER) (Figures 22-1A and 22-1B). The purpose of ER is to limit tension and protect the posterior structures. Patients may remove the sling for showering and exercises, otherwise they are to remain in the sling 24 hours a day. The need for compliance with sling wear should be emphasized, particularly when sleeping.
Initial pain control is often provided by a regional block placed before surgery. Patients should be counseled appropriately regarding when the block will typically wear off so they can adequately control their pain beforehand with the use of oral narcotics and anti-inflammatories. The use of cryotherapy (Figure 22-2) throughout recovery, particularly in the first 7 to 10 days, is important for inflammation and pain control. Advise patients to always keep a layer of protection between the skin and ice to prevent thermal injury. Transcutaneous electrical nerve stimulation should also be used for pain and inflammation in the acute postoperative period as well as throughout recovery. Pain control is important because it can interfere with muscle firing and scapular kinetics.10 Weaning off narcotics in the first 7 to 10 days is strongly encouraged, as patients will often complain of the negative effects of narcotics, such as lightheadedness, constipation, and nausea, with more prolonged usage.
As previously mentioned, during phase I there is a delicate balance between protecting the repaired tissue with immobilization and early ROM to avoid the negative effects of prolonged immobilization. As discussed by McCarty et al,11 gentle early ROM will also help with preventing muscle atrophy, increase tissue circulation, promote healing, and decrease inflammation. There is no restriction on elbow, wrist, and hand ROM exercises that can be performed while a sling. Passive ROM of the shoulder can be performed with the following precautions, 0 degrees of internal rotation (IR), 20 degrees ER and humeral elevation in the scapular plane below 90 degrees. For the first 2 weeks, patients should perform supported Codman pendulum exercises (Figure 22-3) to help maintain passive motion of the glenohumeral joint. Shoulder ROM should be performed either sitting or standing because scapular mobility is restricted when supine. Passive ROM can also be performed by a physical therapist.
While wearing the sling, patients can begin light cardiovascular exercise. This will help patients mentally because they feel limited in many activities following surgery, as well as promote increased blood flow for healing, improve sleep, and help maintain their overall health. Patients can walk on a treadmill or flat surface or ride a stationary recumbent bike during this phase.
Phase II: 2 to 6 Weeks
The goals of phase II include continued immobilization to allow healing of the repair, while minimizing the negative effects of immobilization, progressive increase in passive and active assisted ROM, and to begin restoring proper scapulohumeral and scapulothoracic mechanics.
Patients should continue wearing a sling for 6 weeks. Depending on surgeon preference, patients may start to sleep without a sling at 5 weeks. As previously mentioned, a sling can be removed for showering and daily exercises.
During phase II of recovery patients should be off all narcotic pain medication. Patients should continue to use anti-inflammatories, cryotherapy, and transcutaneous electrical nerve stimulation as needed.
Shoulder ROM will continue to increase throughout phase 2 with use of unsupported Codman and table slides. Passive ROM should remain within the following precautions, and attention should be placed on appropriate scapular motion. Patients will progressively increase passive and active assisted forward flexion from 90 to 120 degrees and passive/active assisted abduction to 90 degrees, and scapular plane elevation to 120 degrees by week 4 and 140 degrees at week 6. Patients should avoid combined abduction and IR, as well as horizontal adduction to avoid placing stress on the posterior structures. Various techniques including manual manipulation, pulleys, and wands can be used to obtain ROM.