Functional Neuromuscular Rehabilitation of Posterior Shoulder Dislocation in a High School Baseball Player

Transcription

1 Functional Neuromuscular Rehabilitation of Posterior Shoulder Dislocation in a High School Baseball Player David Logerstedt Posterior glenohumeral dislocations are rare, comprising only 4 percent of all shoulder dislocations. While early and accurate diagnosis of a posterior dislocation increases the likelihood of success with non-operative management, traditional rehabilitation may not adequately address the sensorimotor deficits that are evident following dislocation. Restoration of the sensorimotor system is critical to successfully return a throwing athlete safely to sports. The use of functional neuromuscular rehabilitation (FNR) attempts to address deficits in the compromised sensorimotor system. With a good understanding of the specific demands placed on the overhead athlete s shoulder, knowledge of glenohumeral and scapulothoracic joints biomechanics, respect for the athlete s level of symptoms and pain, adherence to soft tissue healing, and application of a rehabilitation program that incorporates FNR, an athlete can successfully return to a high level of competition following an acute posterior glenohumeral dislocation. Key Words: glenohumeral, sensorimotor, dynamic stability Logerstedt D. Functional neuromuscular rehabilitation of posterior shoulder dislocation in a high school baseball player. J Sport Rehabil. 2004;13: Human Kinetics Publishers, Inc. Background As the majority of glenohumeral dislocations occur in an anterior and inferior direction, 1,2 less is known about posterior glenohumeral dislocations. Posterior glenohumeral dislocations account for 4 percent of all glenohumeral dislocations 1 and usually are the result of initial trauma involving a posteriorly directed force to a flexed, adducted, and internally rotated shoulder. 2 Non-operative management is favored in instances when the dislocation presents fewer than 6 weeks after injury, with less than 20 percent of a humeral head defect. 3 Traditional rehabilitation, however, may be insufficient for overhead athletes, as only 66 percent of patients following a traumatic posterior dislocation scored good or excellent following a muscle strengthening exercise program. 4 A greater number of patients may be able The author is with PENN Therapy and Fitness, 235 S. 33rd St, Philadelphia, PA

2 168 Logerstedt to successfully return to their prior level of activity if traditional rehabilitation was complimented with a functional neuromuscular rehabilitation (FNR) program. However, little work specifically aimed at addressing the neuromuscular deficits that contribute to posterior shoulder instability have been described for overhead athletes. 6,7 Lephart and Henry developed a classification system to aid in the progression of functional rehabilitation of the sensorimotor system. 7 The role of FNR is to integrate information from the somatosensory receptors, process these signals at the central nervous system, and produce synchronized and synergistic motor responses in order to reduce microtrauma and recurrent injury on joint structures. 7,8 While unknown, it is plausible that rehabilitation incorporating FNR may offer advantages, as it relates to functional outcome measures when compared to that of traditional rehabilitation alone. The purpose of this case report is to describe the rehabilitation of an acute posterior shoulder dislocation in a high school baseball player, with emphasis on dynamic joint stability, reactive neuromuscular control, and throwing motor patterns to effectively return the athlete to a competitive level. History and Physical Examination A 17-year-old high school baseball center fielder posteriorly dislocated his right throwing shoulder following a dive back to first base on an outstretched arm. The shoulder dislocation was reduced in the local emergency department. MRI findings revealed a 7-7-mm impaction injury on the superolateral aspect on the right humeral head (Figure 1). He presented to our department 3 weeks following the injury, wearing a sling in an adducted and internally rotated position and with intermittent mild (2/10) posterior shoulder pain. He was unable to participate in baseball or other sports. Table 1 exhibits the patient s initial objective findings. Ligamentous stability tests to the patient s right shoulder included 1+ out of 3 on the anterior load and shift, 2+ out of 3 on the posterior load and shift, 2+ out of 3 on the posterior fulcrum test, and positive posterior apprehension sign. ROM/Muscle Activation Phase Treatment Regimen Symptom-limited exercises and healing constraints guided the course of treatment. Table 2 illustrates an outline of the treatment regimen. Initial treatment was designed to restore ROM and neuromuscular activity of the shoulder, consisting of submaximal isometrics and active and active-assisted range of motion (ROM) in all planes. As the athlete s symptoms improved,

3 Posterior Shoulder Dislocation 169 Figure 1 An impact injury of 7 7 mm on the superolateral aspect on the right humeral head. Table 1 Objective Findings 3 weeks post injury 11 weeks (initial 5 weeks 8 weeks post injury Variable evaluation) post injury post injury (discharge) AROM Flex N/T 152 (pain) Abd N/T 175 (pain) ER@90 N/T IR@90 N/T PROM Flex 180* 180* 180* 180* Abd 180* 180* 180* 180* ER@90 65^ 104* 104* IR@90 55^ 86* 89* SMTT Flex S/P S/P S/P S/P Abd S/P S/P S/P S/P ER S/P S/P S/P S/P IR S/P S/P S/P S/P *Capsular endfeel; ^empty endfeel. AROM: active range of motion; PROM: passive range of motion; SMTT: selective muscle tension testing; S/P = strong/painless.

4 170 Logerstedt Table 2 Phase Phases and Exercise Progression Exercise progression Immobilization (0 3 weeks) Sling in adducted/internally rotated position ROM/Muscle Activation ROM exercises (3 5 weeks) Shoulder isometrics Rhythmic stabilization exercises Active oscillating techniques for isometric stabilization Scapulothoracic PNF Dynamic joint stability Muscle endurance exercises (5 7 weeks) Closed kinetic chain exercises Reactive neuromuscular Variable resistance strengthening control (7 9 weeks) Plyometrics Simulated throwing activities Throwing (9 11 weeks) PNF with elastic tubing Plyometrics Interval throwing progression he was progressed with rhythmic stabilization exercises and active oscillating techniques for isometric stabilization (AOTIS), emphasizing shoulder ER and IR joint stability (Figure 2). Additionally at this time, scapular proprioceptive neuromuscular facilitation techniques were utilized to enhance dynamic stability of the scapular muscles during arm motion. Dynamic scapular stability is critical for maintaining a functional stable scapulothoracic articulation necessary during the throwing motion. 9 Restoration of normal joint motion in the shoulder cannot be overemphasized. A change or loss of joint movement can stress healing tissues and altered proprioceptive input to the central nervous system. 10,11 This can result in compensatory movements at adjacent joints and lead to adaptations in the motor control system. Rhythmic stabilization and AOTIS techniques allow the clinician an opportunity to increase the patient s awareness of specific movement patterns and reinforce or facilitate weak patterns. 12 Rhythmic and oscillating stabilization exercises can help restore the neurosensory properties of the traumatized shoulder ligaments, enhance the sensitivity of the afferent mechanoreceptors, and provide preparatory and reactive muscle activity as the athlete responds to an unexpected direction of force Proprioceptive neuromuscular facilitation (PNF) exercises have been advocated to enhance balance in the shoulder force couples. PNF pattern diagonal 2 (D2) pattern is frequently used to mimic

5 Posterior Shoulder Dislocation 171 Figure 2 Oscillating technique for isometric stabilization with right shoulder abducted to 90 degrees and in neutral rotation. functional throwing directionality and facilitate triplanar conditioning due to the similarity between its plane of motion and the throwing motion. 15,16 Improvement in shoulder function and enhanced functional throwing performance scores following a 5-week PNF training program has been noted. 17 Scapular PNF can maximally challenge the scapulothoracic muscle force couples and to stimulate the proprioceptive and kinesthetic awareness of the scapula. 9,18 Dynamic Joint Stability Phase. Dynamic joint stability of the shoulder is accomplished through an increase in joint compression, dynamic ligament tension, and neuromuscular control. 9 The patient demonstrating improved muscle activation (strong/painless contractions with selective manual muscle testing) and active ROM greater than 140 degrees of shoulder forward elevation and abduction, determined progression to this phase (Table 1). Muscle activation and endurance exercises focused on the scapular muscles, rotator cuff, latissimus dorsi, deltoids, biceps, and triceps, using the thrower s ten exercises. 12 Strengthening exercises consisted of 2 sets of 10 repetitions and progressed to 3 sets of 10 repetitions as tolerated. Muscle endurance training utilized 2 sets of repetitions and progressed to 3 sets of repetitions as the athlete s endurance improved. Additional selective exercises, including sidelying ER and prone lying with the arm abducted to 100 degrees and full external rotation were utilized to

6 172 Logerstedt Figure 3 Tripod position on unstable surface. increase strength and endurance of the glenohumeral and scapulothoracic muscles. In the absence of patient-reported complaints of pain or instability, along with strong/painless muscle activation in shoulder midranges, closed chain exercises, such as tripod position on wobble board (Figure 3) and scapular plane pushups, were incorporated 6 weeks post-injury to further enhance dynamic joint stability. Reeducation of selective muscle activation through the use of the thrower s ten exercises is used to facilitate muscle balance and synergistic contraction necessary for dynamic stability and neuromuscular control of the unstable shoulder joint. 12,19 Wilk et al. developed these core exercises to specifically address the vital muscles involved in the throwing motion. 9,17 Side-lying external rotation and prone rowing into external rotation elicited the highest amount of EMG activity of the posterior cuff muscles, 20 while prone lying with the arm abducted to 100 degrees and full external rotation elicited the highest amount of EMG activity of the supraspinatus muscle. 21 Rowing, seated press-ups, scaption exercises, and push-ups with a plus provide substantial muscle activity for the parascapular muscles. 22 Fatigue has been shown to alter the shoulder s proprioception and glenohumeral translation. 23,24 Endurance exercises for the rotator cuff muscles should be emphasized in therapy. Closed chain exercises may facilitate co-activation of the glenohumeral and scapulothoracic force couples. 14,25 Closed kinetic chain exercises provide axial loading through the glenohumeral joint and stimulate articular receptors. 7 It may elicit preparatory activity to allow maintenance of the

7 Posterior Shoulder Dislocation 173 weight-bearing position and reactive muscle contraction as the athlete responds to unexpected changes from perturbations or an unstable surface. 9,14,25,26 However, care must be taken, as closed chain exercises are typically in the position of forward flexion, adduction, and internal rotation, with a longitudinal force applied to the humerus. This is the position of greatest vulnerability for posterior shoulder instability. Safe weightbearing exercises in a patient with posterior shoulder instability requires positioning the humerus in the scapular or coronal plane, as this compresses the humerus into the glenoid fossa and reduces stress on the posterior capsule. Care is warranted to avoid placing the shoulder in a position of posterior shoulder vulnerability and in a position for potential anterior shoulder impingement. Reactive Neuromuscular Phase. Reactive neuromuscular control exercises are used to reestablish the preparatory activation and reflexive contraction to prepare the shoulder joint for unexpected forces common in athletic activities. 14 In order to progress to this phase, the patient exhibited full AROM with no pain, minimal subjective symptoms of instability, and the ability to perform the thrower s ten exercises with proper posture and technique. At week 7 post-injury, light plyometrics, including wall dribble (Figure 4) and the two-arm chest pass, were added. Plyometric training consisted of 2 sets of 10 repetitions to emphasize proper posture and technique. This was progressed to 3 sets of 30 repetitions. The work-to-rest ratio for Figure 4 Wall dribble with 2-kg weighted ball.

8 174 Logerstedt this athlete s plyometric training was 1:5 to allow for full recovery. Eight weeks following injury, one hand catching without return (Figure 5) and ER/IR rhythmic stabilization with tubing with the arm abducted to 90 degrees (Figure 6) were incorporated into the rehabilitation program. Close range throwing with a tennis ball was added to facilitate muscle endurance and to initiate a return to the throwing motion. 19 By week 9, emphasis was placed on the progression of plyometrics mimicking the throwing motion (Figure 7). Increased neuromuscular strength and functional motor patterns, involving variable-resistance training with weight machines and a modified throwing progression program, were initiated. (A) (B) Figure 5A B One-hand catch without return.

9 Posterior Shoulder Dislocation 175 Figure 6 ER/IR rhythmic stabilization with tubing, with shoulder abducted to 90 degrees. Plyometrics are a valuable asset in the rehabilitation of the athletic shoulder, as they elicit preparatory muscle activity and may increase muscle spindle sensitivity, enhancing muscle stiffness. 12,14,27 Furthermore, athletic movement patterns at the shoulder mimic the stretch-shortening cycle. 14 Plyometrics are an excellent transition between the strengthening aspect of shoulder rehabilitation and the throwing program. Plyometrics may be used to enhance dynamic stability, enhance proprioception, and gradually increase the functional stresses placed on the shoulder joint. 19,27,28 Swanik et al demonstrated that plyometric training of the shoulder might facilitate neural adaptations that enhance proprioception, kinesthesia, and muscle performance characteristics. 28 Rhythmic stabilization exercises that utilize the application of forces to suddenly displace the joint toward the position of vulnerability require reflex contraction of the rotator cuff to dynamically stabilize the shoulder joint and incorporate sports specificity. 6,14 Variable-resistance strengthening programs tend to strengthen the accelerators (pectoralis major, latissimus dorsi, teres major, and triceps brachii muscles) of shoulder movement and are used to complement the strengthening of the decelerators (infraspinatus, teres minor, and deltoid muscles) with elastic tubing. 9

10 176 Logerstedt (A) (B)

11 Posterior Shoulder Dislocation 177 (C) Figure 7A C Shoulder ER, IR plyometrics, with shoulder abducted to 90 degrees. Throwing Phase From week 9 11, our athlete completed a modified interval-throwing program while maintaining the variable-resistance training program (Table 3). Wilk et al describe specific criteria in order to initiate an interval-throwing program: (1) satisfactory clinical examination, (2) nonpainful range of motion, (3) satisfactory isokinetic test results, and (4) appropriate rehabilitation progress. 19 Our athlete had no complaints of pain or shoulder instability. He demonstrated nonpainful full AROM and strong/painless contractions with selective muscle tension testing. He exhibited mild passive joint instability (1+/3, with all joint instability testing from the initial evaluation), and he progressed through the rehabilitation process appropriately and without difficulty. Throughout the throwing program, he had no complaints of pain or soreness during or following the session. An interval-throwing program advocated by Reinhold and associates 29 was modified in order to return our athlete to competition in time for potential playoff games. An interval throwing program is designed to gradually increase the quantity, distance, intensity, and type of throws needed to facilitate the gradual restoration of normal throwing biomechanics. 19,29 The intervalthrowing program is referred to as functional rehabilitation that simulate sports activity. 29 These are designed to progressively apply forces to the healing structures and are intended to gradually return the athlete to full athletic competition as quickly and safely as possible.

12 178 Logerstedt Table 3 Modified Interval Throwing Program Phase 1 Phase 2 Phase 3 Step 1: Step 3: Step 5: A. Warm-up throwing A. Warm-up throwing A. Warm-up throwing B. 25 (15 throws) B. 50 (25 throws) B. 100 (25 throws) C. Rest 5 minutes C. Rest 5 minutes C. Rest 5 minutes D. 25 (25 throws) D. 75 (25 throws) D. 100 (25 throws) Step 2: Step 4: Step 6: A. Warm-up throwing A. Warm-up throwing A. Warm-up throwing B. 50 (25 throws) B. 75 (25 throws) B. 100 (25 throws) C. Rest 5 minutes C. Rest 10 minutes C. Rest 5 minutes D. 50 (25 throws) D. 90 (25 throws) D. 125 (25 throws) E. Rest 5 minutes E. Rest 10 minutes E. Rest 10 minutes F. 50 (25 throws) F. 90 (25 throws) F. 150 (25 throws) Step 7: Begin throwing off the mound or return to respective position Outcome Eleven weeks following the posterior dislocation of his right shoulder, our athlete had full active ROM (Table 1) and strong/painless contractions to resisted selective muscle testing in his right shoulder. He had mild clinical joint instability with clinical testing. He exhibited no pain or symptoms of instability with throwing. A dynamic arm stability test was performed to provide a measure of dynamic shoulder stability. 30 This test consists of individuals maintaining a single-arm tripod position as still as possible with the involved limb on a stable surface and the feet on an unstable surface. The amount of sway and the number of compensatory touchdowns is counted over a 20-second period. Our athlete exhibited only 1 touchdown with dynamic arm stability test (Figure 8), with 0 touchdowns on the uninvolved left upper extremity. At this time, our athlete was ready to return to competitive baseball but unfortunately did not, as his team did not qualify for the playoffs, and he was to graduate in the spring. Comments Posterior shoulder dislocations are a rare occasion in athletics. This injury is most frequently seen in football lineman, weightlifters, throwers, swim-

13 Posterior Shoulder Dislocation 179 Figure 8 Dynamic arm stability test position. mers, and racket sport athletes. 1 In the majority of cases, posterior dislocations are unappreciated at initial presentation. 3,5 Fortunately, our athlete was correctly diagnosed in the emergency department and was followed up with imaging studies by an orthopaedic surgeon. Non-operative management of posterior shoulder instability is favored in instances when the dislocation presents acutely with a mild humeral head defect. 3 Burkhead and Rockwood noted, following a dislocation, the shoulder becomes stable at approximately 5 weeks and is maximally stable at approximately 14 weeks. 4 Two thirds of patients with recurrent posterior instability responded successfully with a comprehensive strengthening program, with reports of decreased pain and increased stability. 1,4,5 The strengthening program typically consisted of rotator cuff and parascapular strengthening with the use of elastic tubing or a weighted pulley system. However, it is unclear if these individuals returned to high-level overhead sporting activities. Disruption of ligamentous and capsular structures may result in some level of deafferentation of articular mechanoreceptors. 13 Functional rehabilitation is believed to increase the sensitivity of peripheral afferents present in both the capsuloligamentous and musculotendinous structures, reestablish afferent pathways, elicit preparatory and reactive muscle contractions, and increase muscle stiffness. 14 FNR should incorporate aspects to maximally stimulate somatosensory mechanoreceptors and facilitate spinal cord reflexes, brain stem processing, and cortical planning. 7,8,14 All aspects of functional movement, including isometric, concentric, and

14 180 Logerstedt eccentric muscle control, articular loading and unloading, controlled acceleration and deceleration, and conscious and subconscious appreciation, should be encompassed within the rehabilitation process. 6 I would like to acknowledge the limitations of this case report. Although the primary emphasis was on the rehabilitation of the sensorimotor system of the shoulder, assessing the sensorimotor system in the shoulder without the use of specialized equipment is more challenging. Research and clinical facilities that have access to proprioceptive and isokinetic equipment can assess proprioception and isokinetic strength of the shoulder more readily. However, many therapy clinics lack these resources and must rely on goniometric and functional testing to determine if the sensorimotor system has been compromised and then successfully rehabilitated. Although the athlete was ready to return to competitive baseball, but did not due to situations beyond his control, would he have been able to participate without further incident? Many athletes return to sports following an injury and are re-injured, and many return with no further problems. I can only state here that he was ready to return to competitive baseball. This is a case report on an overhead thrower; therefore, I focused the functional training relevant to an overhead thrower. However, the rehabilitation of different types of throwers (football quarterback, discus thrower, underhand softball pitcher) and non-throwers (outside hitter in volleyball, weightlifter with shoulder injuries) may differ from this case report. Summary Posterior glenohumeral dislocations occur infrequently in athletics. While early and accurate diagnosis of a posterior dislocation increases the likelihood of success with non-operative management, traditional rehabilitation following posterior glenohumeral dislocation may be insufficient for the overhead athlete. I have presented a functional neuromuscular rehabilitation treatment program that successfully prepared an overhead athlete to return to sport following a traumatic posterior shoulder dislocation. The results of this case study suggest that, in addition to the traditional rehabilitation program, incorporation of a functional neuromuscular rehabilitation program following traumatic posterior shoulder dislocation may be beneficial for the overhead athlete. However, controlled research studies that compare the clinical and functional outcomes of these programs in a patient population is necessary. References 1. Fronek J, Warren RF, Bowen M. Posterior subluxation of the glenohumeral joint. J Bone Joint Surg Am. 1989;66:

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