Subacromial corticosteroid injections transiently decrease suture anchor pullout strength: biomechanical studies in...

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Pharmacology

Background:

• Arthroscopic rotator cuff (RC) repair utilizes suture anchors for tendon reattachment to bone.
• The integrity of the anchor-bone interface is crucial for successful RC repair.
• The impact of corticosteroid injections on this interface remains a significant clinical question.

Purpose of the Study:

• To investigate the biomechanical effects of single and multiple corticosteroid injections on suture anchor pullout strength.
• To determine the time course of these effects on the anchor-bone interface.

Main Methods:

• Fifty rats were allocated to control (saline), single methylprednisolone acetate (MTA), or triple MTA injection groups.
• Suture anchors were inserted into the humeral head's greater tuberosity (GT).
• Biomechanical testing assessed anchor pullout strength and stiffness at 1 and 4 weeks post-injection.

Main Results:

• One week post-injection, both single and triple MTA groups showed significantly reduced mean maximal pullout strength and stiffness compared to controls.
• By four weeks, pullout strength significantly increased in both MTA groups compared to the 1-week time point.
• At four weeks, single MTA injection resulted in 92.8% of control pullout strength.

Conclusions:

• Corticosteroid exposure significantly impairs suture anchor pullout strength at one week.
• This detrimental effect is transient, with strength largely recovering by four weeks.
• A waiting period between corticosteroid injection and rotator cuff repair surgery is indicated.