Residual Grip and Pinch Strength Deficits After Completion of Hand Rehabilitation

Abstract

Introduction: Grip and pinch strength are commonly used to document progress in the hand rehabilitation process and in return to work clinics. Grip strength measurement is widely studied; however, pinch strength measurements are not well documented. The majority of the studies on grip and pinch strength were conducted on healthy participants, and there is a dearth of studies on people with hand injuries. Patients who undergo hand rehabilitation have various diagnoses, and the type of diagnosis may affect the residual hand force deficits. Objectives: To examine whether there are residual hand force deficits after the completion of the rehabilitation process by comparing grip and pinch strength between the injured and uninjured hand, to explore whether the type of diagnosis affected these deficits, and to investigate whether there are gender, age, and dominancy differences in these deficits. Materials and Methods: Data were collected retrospectively from 234 participants (174 males and 60 females) with hand injury who were referred to the hand clinic for functional evaluation after completion of the rehabilitation process using the EVAL computerized system. Mean number of years after injury was 3.05 (standard deviation [SD], 2.78). Mean age was 39.2 (SD, 14.7) years. Outcome measures include the average grip strength (in kilograms) of 8 trials measured at the second handle position during the rapid exchange grip force test, and the average of 3 trials of lateral pinch, tripod pinch, and tip pinch (in kilograms). Both injured and uninjured hands were evaluated. The deficits in hand force were calculated using the formula: (Injured hand / Uninjured hand) × 100. The participants were divided into 5 groups according to the type of injury as follows: elbow and shoulder fractures, musculoskeletal disorders in the upper extremity, finger injury (limited active range of motion in the fingers due to fractures of the phalanges or tendon injury), wrist fractures, and nerve injuries (postrelease or repair surgery). The data were analyzed using the general linear model for repeated measures (SPSS). Results: There were significant differences in hand force between the injured and uninjured hands after completion of hand rehabilitation for all injury groups ( P < .05). There were no significant differences in grip and pinch force deficit whether the dominant or nondominant hand was injured. Grip strength deficits ranged from 20% to 30%, whereas pinch strength deficits ranged from 40% to 50%. There were no significant differences in both grip and pinch strength between the 5 injury groups or between men and women. Conclusion: The significant differences in grip and pinch strength between the injured and uninjured hands indicated that there were residual deficits in hand force after completion of the rehabilitation process. Yet, mean grip strength in the injured hand was greater than 9 kg and mean pinch strength was greater than 2 kg, indicating that despite those deficits, hand force in these participants was considered functional. Furthermore, hand force deficits after completion of the rehabilitation process were not affected by gender or by the location and type of injury.