University of Groningen
Grip on prognostic factors after forearm fractures
Ploegmakers, Joris Jan Willem
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Publication date: 2019
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Ploegmakers, J. J. W. (2019). Grip on prognostic factors after forearm fractures. Rijksuniversiteit Groningen.
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J.J.W. Ploegmakers B. The A.W. Wang M. Brutty T.R. Ackland Hand Surgery 2015;20(3):430-4
Chapter 7
Supination and pronation strength deficits persist at
2-4 years after treatment of distal radius fractures
ABSTRACT
Forearm rotation is a key function in the upper extremity. Following distal radius fracture, residual disability may occur in tasks requiring forearm rotation. The objectives of this study are to define pronation and supination strength profiles tested through the range of forearm rotation in normal individuals, and to evaluate the torque profiles and torque deficits across the testing range in a cohort of patients treated for distal radius fracture associated with an ulnar styloid base fracture.
In a normative cohort of 29 subjects the supination strength profile showed an increasing linear relationship from supination to pronation. Twelve subjects were evaluated 2-4 years after anatomical open reduction and volar plate fixation of a distal radius fracture. The injured wrist was consistently weaker (corrected for hand dominance) in both supination and pronation strength in all testing positions, with the greatest loss in 60 degrees supination.
Mean supination strength loss across all testing positions was significantly correlated with worse PRWE scores, highlighting the importance of supination in wrist function.
INTRODUCTION
Extra articular displaced fractures of the distal radius are commonly treated by open reduction and volar locking plate fixation. Recent clinical outcome studies report a significant prevalence of ongoing disability due to ulnar sided wrist pain and distal radioulnar joint (DRUJ) dysfunction.1,2,3,4,5,6,7,8,9 This is more common in younger patients without osteoporosis
where fractures may occur with a higher injury force, with associated damage to the triangular fibrocartilage or distal radioulnar ligaments.10,11,12,13,14 Female patients of middle age in particular
are reported to have ongoing pain and disability after distal radius fracture.7
DRUJ dysfunction has been clinically assessed by manual stress test such as the ballottement test and piano key sign.15 In addition, CT assessment,16 DRUJ stress radiography,17 and instrumented
distal ulnar translation,18 have also been used to objectively assess DRUJ dysfunction.
Matsuoka using a custom device measured pronation and supination strength in normal individuals at neutral rotation, 60 degrees pronation, and 60 degrees supination.19 They concluded
that torque strength measurements are reliable and should be collected when treating patients with forearm dysfunction. Wong evaluated a portable baseline hydraulic dynamometer (BHD)
to measure isometric forearm torque strength.20 They found this device was valid compared to a
Cybex 6000 dynamometer with high inter-rater and intra-rater reliability when testing pronation and supination strength in 18 volunteers. Forearm torque strength testing may be a useful measure of residual DRUJ dysfunction after treatment of distal radius fracture.
Huh has reported isokinetic pronation strength but not supination strength returned to normal at 12 months after open reduction and volar plate fixation of distal radius fracture in both male
and female subjects.21 However, it is noted that only 51% of fractures were associated with an
ulnar styloid fracture, and the level of styloid fracture was not specified. These authors reported that at this short-term review, the supination strength deficit had no effect on clinical function, as assessed by DASH scores.
The goals for this study are twofold; first to measure the strength of pronation and supination across a wide range of forearm rotation, and with a validated device establish a physiologic torque profile in non injured subjects. The second goal is the mid term evaluation of isometric torque profiles in a patient cohort, who previously had undergone open reduction and volar locking plate fixation for treatment of a distal radius fracture associated with an ulnar styloid base fracture. We hypothesise that torque profiles remain altered in the mid term following surgery, and torque deficits correlate with a poorer clinical function.
METHODS
Institutional ethics committee approval was received for the study protocol and informed consent was obtained from all participants.
Participants
A normative cohort comprising of 29 female hospital and university volunteers (mean ± SD age = 22.2 ± 3.6 y) with no history of hand or upper limb disorders were evaluated for pronation and supination strength. The majority (n=24) were right hand dominant.
The patient cohort comprised adult female patients who had undergone open reduction and volar locking plate fixation of an extra-articular displaced fracture of the distal radius associated with a base of ulnar styloid fracture. Study inclusion criteria included distal radius union in anatomical position, and follow up 2-4 years after surgery. Exclusion criteria included multiple trauma, documented injury to the contralateral upper extremity, neuromuscular disease and active compensation claims. Of 25 patients meeting the selection criteria, 12 women (mean ± SD age = 47.8 ± 19.0 y) were available for evaluation for this study.
Five patients had sustained fractures that involved the dominant arm. Six of the 12 subjects reported ongoing pain in the injured wrist. All participants completed the forearm torque testing protocol, and patients in the fracture group were assessed clinically by completing the Quick DASH (maximum disability score of 100), the patient rated wrist evaluation PRWE, a 15-item questionnaire measuring wrist pain, and functional difficulty with daily activities with a maximum overall score of 100.
Forearm PronoSupination Strength Testing Protocol
All participants underwent a single session of strength testing. Pronation and supination strength were assessed with a Baseline® hydraulic dynamometer (BHD) (Fabrication Enterprises, White Planes, NY). The BHD was fitted with a “shovel handle” grip and was mounted on a frame with the ability to rotate and lock the device in varying degrees of pronation (60°, 40°, 20°), supination (60°, 40°, 20°) and in neutral (0°). Participants were instructed by a single assessor to sit grasping the handle with the elbow positioned in 45° of flexion and resting on the thigh. The shoulder joint was thus maintained in neutral rotation; external rotation of the glenohumeral joint has been shown to be a variable affecting supination strength.22,23 The forearm was positioned horizontally
in line with the axle of the BHD shovel handle, and the chair and table allowed seated height to be adjusted for correct positioning (Figure 1). Participants were instructed to perform two pre-test maximal isometric contractions, one of pronation, the other of supination, with the verbal prompt “contract as hard as you can without compromising your wrist, elbow and shoulder positioning”. Participants then repeated the pronation and supination assessment at each of the test angles using the same verbal prompts. If the wrist, elbow or shoulder position was compromised during testing, the trial was repeated. Both left and right hands were assessed, and the participant was allowed 1 minute rest between trials to recover before testing recommenced at the next angle. Test angles and hands were presented in random order. Strength and ROM assessments were performed by an accredited exercise physiologist.
The normative cohort of healthy volunteers was used to construct physiologic pronation and supination torque strength profiles across the seven testing positions of forearm rotation. Differences in absolute torque strength and percentage difference between dominant and non-dominant sides were measured to calculate a non-dominant versus non-non-dominant correction factor for application in the fracture study group. For the fracture group the absolute loss in pronation and supination torque strength of the injured wrist compared to the uninjured wrist was calculated, after correction for hand dominance. Loss of pronation and supination strength was correlated with the clinical function questionnaire scores using a Pearson correlation. Statistical analysis were performed using SPSS v20.0 (IBM, New York, USA) and significance was accepted at p<0.05.
Figure 1. Baseline ® hydraulic dynamometer on mounted frame with measurement angles marked at neutral
(0°) and 20°, 40° and 60° degrees of pronation and supination.
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o
RESULTS
In the normative cohort, the supination and pronation torque tests across the seven testing positions of forearm rotation are shown in Figure 2 and Figure 3. The physiologic torque profiles show supination strength increases in a generally linear fashion from the testing position of 60 degrees supination to 60 degrees pronation. Conversely pronation strength decreases in a generally linear fashion from 60 degrees supination to 60 degrees pronation.
The normative cohort was also used to measure the effect of hand dominance on torque strength across the testing range. The effect of hand dominance on supination torque was generally less than 10%, while the effect on pronation torque was slightly greater. At each test position, and for both pronation and supination, a dominant versus non-dominant side torque difference (%) was calculated for use as a correction factor in the fracture cohort.
The fracture cohort torque strength loss relative to the uninjured contralateral extremity and corrected for hand dominance is shown in Table 1. Persisting loss of supination strength and more minor loss of pronation strength occur in all testing positions compared to the non-injured
Table 1. Relative Mean Supination and Pronation Strength Loss for the Fracture Cohort after Correction for
Hand Dominance.
Note: Abbreviations: for example 60s = measured with the forearm in 60 degrees of supination; N = neutral forearm position; 60p = measured with the forearm in 60 degrees of pronation.
Measure and Position Strength loss (kg) (95% CI)
Supination strength 60s 27.1 (3.7 to 50.4) 40s 16.1 (-3.4 to 35.5) 20s 18.3 (-4.5 to 41.2) N 13.7 (-4.8 to 32.1) 20p 20.2 (4.7 to 35.6) 40p 16.4 (-0.1 to 32.9) 60p 19.3 (-4.9 to 43.6) Overall mean 18.7 (11.3 to 26.1) Pronation strength 60s 27.8 (-4.2 to 59.9) 40s 22.1 (-8.8 to 52.9) 20s 12.9 (-25.8 to 51.6) N 2.8 (-31.0 to 36.5) 20p 14.5 (-17.7 to 46.7) 40p 4.0 (-18.0 to 26.0) 60p 12.5 (-11.0 to 36.0) Overall mean 13.8 (2.4 to 25.2)
extremity. The maximum relative loss of both supination and pronation strength occurs at 60 degrees supination. In this position, mean supination strength loss is 27.1kg (CI 3.7 to 50.4) and the loss of pronation strength is 27.8kg (CI -4.2 to 59.9).
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Figure 2. Normative Cohort (n=29). Mean peak supination stength for left and right hands at each forearm
angle. Note: (s)=supinated position and (p)=pronated position. Error bars represent standard deviation values.
Supina
tion str
ength (k
g)
Angles of supination (s) and pronation (p)
Female left Female right
Figure 3. Normative Cohort (n=29). Mean peak supination stength for left and right hands at each forearm
angle. Note: (s)=supinated position and (p)=pronated position. Error bars represent standard deviation values.
Pr ona tion str ength (k g) Female left Female right (s) 60 (s) 40 (s) 20 0 (p) 20 (p) 40 (p) 60 140 120 100 80 60 40 20 0 140 120 100 80 60 40 20 0 (s) 60 (s) 40 (s) 20 0 (p) 20 (p) 40 (p) 60
Clinical function evaluation indicated 6 of 12 patients still reported significant pain in the injured wrist at 2-4 years after surgery. The patient rated functional questionnaire scores are shown in Table 2. The mean score of the QuickDash was 13.9 out of 100. Using the PRWE mean score was 17.7 out of 100 indicating residual dysfunction.
Correlation of strength loss with clinical function scores show that the mean supination strength loss across the 7 testing positions for each subject correlated with worse PRWE scores (correlation coefficient = 0.57, p = 0.05) highlighting the importance of supination in wrist function.
Table 2. Mean score of subjective test in patients.
Clinical Test Mean Score (SE)
qDASH (0-100) 13.9 (3.4)
DISCUSSION
Distal radius fractures are common over the age of 50 years. Despite an operative approach to achieve anatomical reduction and rigid fixation of the radius fracture, ongoing disability may occur and this is frequently referable to the distal radioulnar joint causing impaired function involving forearm rotation.14,24
The findings of this study indicate that middle aged female subjects with anatomically healed extra articular distal radius fractures associated with a basal ulnar styloid fracture have persistent loss of isometric supination and also pronation strength at 2-4 years after surgery. The loss in forearm torque strength is observed across a broad range of forearm rotation though is most notable at 60 degrees supination. This study reports that even with the small subject numbers, the loss of supination strength in particular, correlates with worse PRWE scores, and highlights the importance of supination function in daily activity. The 60degrees supination testing position is the relatively most weak testing position, and this has clinical implications for self care activities such as behind the back dressing (eg fastening a brassiere) and perineal care which are supination dependent activities.
The 60 degrees supination position for forearm torque testing may be of value in routine objective assessment of wrist function. Matsuoka recommended the use of a custom made device for
torque strength measurements for patients undergoing treatment for forearm dysfunction.19 In
our study we use a commercially available and validated device and tested it in 7 positions across the range of forearm rotation from 60 degrees supination to 60 degrees pronation. This protocol is time consuming and impractical as a routine assessment. However this study has identified the 60 degrees supination position as the single testing position where maximum reduction in both supination and pronation strength occurs. In this 60 degrees supination testing position, pain inhibition or residual DRUJ instability may account for the observed torque deficits.
The limitations of this study include the small number of fracture subjects evaluated. Larger subject numbers may have revealed a positive correlation of torque deficits with quick DASH as well. Also the torque strength measurement required a firm grasp on the testing device handle, and this may have been compromised by concomitant pathology for example thumb carpometacarpal osteoarthritis or lateral epicondylitis. We therefore only evaluated younger patients (mean age 47 y at the time of fracture) and tested with the elbow in the flexed and supported position. A further limitation in this study is that no advanced imaging or arthroscopic information was available to assess the exact nature of DRUJ pathology accounting for the subjective and objective wrist deficits. However this study is a pilot study to introduce the forearm torque testing protocol. Future research will include prospective studies of larger subject numbers to evaluate torque strength after distal radius fractures and following treatment and rehabilitation.
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