The comparison of preventive analgesia with methylprednisolone plus gabapentin versus methylprednisolone alone in elderly patients undergoing total knee arthroplasty

The comparison of preventive analgesia with methylprednisolone plus gabapentin versus methylprednisolone alone in elderly patients undergoing total knee arthroplasty

This clinical trial will be conducted with two parallel groups: one receiving methylprednisolone in combination with gabapentin and the other receiving methylprednisolone without gabapentin, with no control group. The study will follow a double‑blind, randomized design in phase 2–3 and will enroll 140 patients. Randomization will be performed using permuted blocks of four.

Study site: Orthopedic and Anesthesia Departments of Imam Reza Hospital, Tabriz, Islamic Republic of Iran; study population: patients over 60 years of age scheduled for elective unilateral total knee arthroplasty; type of blinding: double-blind; blinding procedure: both patients and outcome assessors were unaware of group assignments, and medications were prepared as identical oral capsules and injectable ampoules coded as A and B by an independent pharmacist.

Inclusion criteria: patients aged over 60 years; physical status class I or II according to the American Society of Anesthesiologists (ASA) classification; candidates for elective unilateral total knee arthroplasty; receiving preemptive analgesia with methylprednisolone beta alone or combined with gabapentin. Exclusion criteria: any contraindication for spinal anesthesia; previous use of corticosteroid medications.

Intervention group (Group A): patients in this group will receive methylprednisolone combined with gabapentin as preemptive analgesia before total knee arthroplasty. Control group (Group B): patients in this group will receive methylprednisolone alone, without gabapentin, as preemptive analgesia prior to surgery.

Postoperative pain

In this study, with a sample size of 140 participants, patients will be allocated into two groups using the block permutation randomization method. Each block will contain four patients, including all possible combinations: Block 1 – BBAA, Block 2 – AABB, Block 3 – ABAB, Block 4 – BABA, Block 5 – ABBA, and Block 6 – BAAB. For 140 participants, 35 blocks will be used, and block numbers from 1 to 6 will be randomly selected with the aid of Random Allocation Software. For example, if Block 6 is chosen as the first block and Block 2 as the second, the allocation sequence will be BAABAABB, assigning individuals to either the methylprednisolone plus gabapentin group (A) or the methylprednisolone without gabapentin group (B). To ensure allocation concealment, the randomization list will be prepared by an independent researcher who will not be involved in patient recruitment or assessment. The list will be numbered and sealed inside opaque, sequentially numbered, light‑impermeable envelopes. The principal investigator will open the envelopes in numerical order only after each participant has been enrolled and assigned a code, thereby preventing any prediction of group assignment.

In this double-blind study, both patients and outcome assessors were kept unaware of group assignments by preparing the two medications in identical capsules with the same shape, size, color, and taste, manufactured and packaged by an independent pharmacist. Each capsule was labeled only with codes “A” and “B,” determined by a randomization table generated by an independent investigator. Thus, neither the patients, nor data analysts were informed of the assigned intervention, and the coding list remained confidential with the pharmacist until the completion of statistical analysis to ensure full blinding integrity.