Relation Between Hand Grip and Shoulder Muscle Strength After Surgical Stabilization of Shoulder Dislocations

Relation Between Shoulder Lateral Rotators Strength and Hand Grip Strength After Arthroscopic Bankart Repair Surgery

To investigate the correlation between shoulder lateral rotators strength (LRS) and hand grip strength (HGS) at different shoulder positions in patients following arthroscopic Bankart repair surgery for anterior shoulder instability.

Anterior shoulder instability is a common clinical problem with a high incidence rate in athletes (Zacchilli and Owens., 2010). It may be a result of anterior force trauma to elevated, horizontally abducted, and externally rotated shoulder. In this position, stability is provided by the subscapularis, GH ligaments (particularly the anterior band of the inferior ligament), and the long head of the biceps (Ladd et al., 2021b). A high energy trauma may affect these structures, along with the attachment of the anterior capsule and glenoid labrum (Bankart lesion) (Ladd et al., 2021a) Traditionally, patients with first-time dislocation are managed conservatively however, the recurrence rate is high especially in the teenagers and younger population (Polyzois et al. 2016). in case of recurrent dislocation, surgical repair of the affected structures is performed either by open or arthroscopic approach (Kane et al., 2015).

After surgery, dynamic stability of the shoulder is important to ensure the repaired capsule, anteroinferior labrum and/or the inferior glenohumeral ligament are not vigorously stressed and compromised during daily living activities (Mueller et al., 2005) The muscles responsible for shoulder rotation serve as active stabilizers for the glenohumeral joint, and regaining strength in these muscles is crucial for stabilizing the joint during the recovery process after surgery (Edouard et al., 2012). In a previous study, researchers examined the progression of rotational muscle strength before and after open Bankart and modified Bristow procedures. The findings indicate that adequate muscle strength can be achieved six months post-surgery. Furthermore, the strength of these rotational muscles is closely linked to shoulder function and could serve as a useful indicator of glenohumeral instability following surgery (Amako et al., 2008).10 A cohort study found that after 4-8 months of postoperative Bankart repair, about 74% of patients regained their baseline range of motion and strength (Buckwalter V et al., 2018).

In a 13-year follow-up study, it was found that patients with less than 6 months of postoperative rehabilitation after arthroscopic Bankart repair surgery had an increased rate of recurrent dislocation (Aboalata et al., 2017).

Many studies found a positive correlation between hand gripping activity and rotator cuff muscle activity in healthy subjects. It was found that hand loading induces an elevation in intramuscular pressure within the supraspinatus (SSP) and infraspinatus (ISP) muscles (L. V. Roberts et al., 2008; Shenouda and El-Tokhy., 2014).

Previous literature advocates a relation between grip strength and the overall strength of the upper body, as well as it serves as an objective indicator of upper extremity function (Vaishya et al., 2024). Other studies have shown a positive correlation between isometric hand grip strength and isokinetic peak torque and work of the shoulder stabilizing muscles (Mandalidis and O'Brien 2010; Nascimento et al., 2012). This relationship suggests that a stable proximal shoulder girdle is necessary to facilitate optimal recruitment of distal muscles and effective transmission of force along the myofascial pathways (Huijing and Baan., 2003).

There are different mechanisms through which handgrip exercises elevate shoulder muscle activity. It was observed that the rotator cuff muscles, particularly the SSP and ISP, are more impacted by hand loading due to their role as stabilizers of the shoulder joint compared to muscles responsible for elevation such as the deltoid (D. R. Lee and Kim., 2016). Given that, maintaining stability of the glenohumeral joint (GHJ) is a primary function of the SSP and ISP, it is logical to anticipate an increase in their activity during hand activities to uphold joint stability (Blache et al., 2017).

Previous literature found that hand grip strength can be quantified by measuring the amount of static force that the hand can apply on the hand grip dynamometer that provides an objective index of the functional integrity of the upper extremity (Massy-Westropp et al., 2011). Another study showed that grip strength can be reliably used to assess the function of the lateral rotators of the shoulder in normal individuals (Horsley et al., 2016).

Up to author best knowledge, there is limited literature considering the correlation between hand grip strength and shoulder lateral rotator strength in patients with post Bankart repair surgery. Therefore, this study aims to assess the relation between hand grip strength and shoulder lateral rotators strength in various shoulder positions in patients who have undergone arthroscopic Bankart repair surgery six months postoperatively

Inclusion Criteria:

1. Patients with arthroscopic Bankart repair surgery.
2. Patients have passed 6 months after surgery.
3. Patients have not surpassed 12 months from surgery
4. Age of the patient ranged from 18 to 40 years to avoid including people with potential degenerative rotator cuff tears.
5. Patients immediately started physical therapy program after surgery for 6 months.
6. Nearly or complete full ROM.
7. Absence of shoulder pain.
8. Normal contralateral arm without previous surgeries.

Exclusion Criteria:

1. Other associated surgeries such as slap repair or large humeral bone defect requiring remplissage.
2. Moderate to severe shoulder pain.
3. Incomplete ROM.
4. Presence of nerve injury after the initial trauma.
5. Past history of other previous surgeries on the affected limb.
6. Any surgery or musculoskeletal disorder related to the neck or the contralateral upper limb.