Recovery of grip strength and hand dexterity after distal radius fracture: A two-year prospective cohort study

Abstract

Introduction

Clinicians often evaluate deficits after an injury by comparing the injured and uninjured side. It is important to understand what deficits occur in hand function after distal radius fracture, how they change over time and their clinical relevance. The purpose of this study was to evaluate the differences in grip strength and hand dexterity between the injured and uninjured hands of patients two years following distal radius fracture.

Methods

Patients with distal radius fracture were recruited in a specialized hand clinic. Grip strength and hand dexterity were examined bilaterally with a Jamar hand-held dynamometer and with the NK dexterity device at 3, 6, 12 and 24 months’ post-injury respectively. Generalized linear modeling was performed, with age and sex as covariates to assess changes over time, and between sides.

Results

Patients (n = 154) exhibited mean differences of grip strength between injured and uninjured side at 3 months’ (12.09 kg) and 6 months’ (7.47 kg) follow-up. The associated deficit standardized response means (SRM) were 1.30 and 0.73, respectively. At 2-years follow-up the mean deficit on the injured side was 2.30 kg with SRM = 0.22. One hundred and eleven patients who completed dexterity testing demonstrated small to trivial side to side differences across all time points.

Conclusions

There were clinically important differences in grip strength between the injured and uninjured hands in patients with a distal radius fracture at 3 and 6 months’ follow-up. However, at 12 and 24 months, grip strength differences were small and of uncertain clinical importance. Trivial to small differences in hand dexterity can be expected between the injured and uninjured hand by 2 years after distal radius fracture.

Keywords

Distal radius fracture grip strength hand dexterity recovery

Introduction

Distal radius fracture (DRF) is one of the most common fractures among all ages.^1–3 Emerging evidence from epidemiological studies of upper extremity fractures indicates that the radius and ulna are the most common fractures with an annual incidence of 16.2 fractures per 10,000 person-years in the United States.³ It has been reported that the increased rates of DRF incidence in the United States and around the world are due to multiple reasons.⁴ The economic and social burden associated with those fractures is significant in terms of medical cost, lost hours of work and education, potential loss of independence and probably prolonged disability.²

There is no consensus on a standard effective management of DRF and clinicians often apply different strategies and rehabilitation protocols.⁵ Substantial improvements have been made in terms of diagnosis and in the management of distal radius fractures; however, sometimes pain and/or stiffness may be present in the long term after the injury in the affected joint.⁵

The assessment of hand function is very important during the rehabilitation phase because the main goal of hand therapy is to improve hand function.⁵ Indications of individuals’ functional ability include self-reported outcomes as well as performance based tests. Clinicians often evaluate deficits after an injury by comparing the injured and uninjured side.⁶ It is important for clinicians to understand what deficits occur in hand function after distal radius fracture (DRF), how they change over time and their clinical implications. Therefore, the primary objective of this prospective cohort study was to evaluate the recovery of hand grip strength and compare the differences between the injured and uninjured hand 2 years after DRF. The secondary objective of this study was to examine the recovery of hand dexterity and compare the differences between the injured and uninjured hand 2 years after DRF.

Methods

Study design

A prospective cohort study was designed and the manuscript was prepared according to the STROBE reporting guidelines.⁷ Institutional research ethics approval was obtained from Western University scientific board in London, Ontario, Canada.

Setting

The recruitment and data collection took place at the Roth McFarlane Hand and Upper Limb Centre at St. Joseph’s Hospital in London, Ontario, Canada. Patients who sustained DRF were asked if they wanted to participate in the study. Assessments of hand dexterity and grip strength took place from September 2011 until August 2015 at 3, 6,12 and 24 months following DRF. Patients were informed that follow-up visits would coincide with usual follow-up occasions to assess their recovery.

Participants

Patients aged 18 to 85 years were eligible to participate in the study if they had sustained a DRF. Patients who had neurological disorders, comorbidities or any other condition or disease that affected their ability to manipulate an object or were unable to communicate were excluded. Written informed consent was signed by all participants. Two research assistants collected the demographic data such as brief medical history, age, sex, hand dominance, injured side, grip strength on the injured and uninjured hand and bilateral hand dexterity. Measurements of hand dexterity and grip strength were collected at 3, 6, 12 and 24 months’ after the fracture.

Outcomes

The independent variables were age (years), sex (male or female), hand dominance (left or right hand, injured side (left or right hand) and if they had a cast, physiotherapy treatment and/or surgery after the fracture.

Dependent variables were hand grip strength and hand dexterity. Hand dexterity was tested with the NK hand dexterity board (NKHDT), a timed test which consists of three different subtests of hand dexterity tests (small, medium, and large objects). The NKHDT has demonstrated reliability coefficients (ICC) ranging from 0.53 to 0.85 with dominant hands being more consistent than non-dominant hands.⁸ Concurrent construct validity of the NKHDT was demonstrated with the Jebsen’s Hand Function Test.⁹ The correlation ranged from moderate to strong (r = 0.47–0.87) and was much stronger when the objects were similar in size.¹⁰ Previous studies have been found that the NKHDT is a responsive test to evaluate dexterity recovery from DRF.¹¹ The measurements of hand dexterity were performed according to the testing protocol of Turgeon et al.⁸ Participants were seated and completed two repetitions of manipulating/moving objects across the board, and then returning them to their original positions. Subtests were performed containing small, medium and larger objects. The mean score from two repetitions was averaged for each subtest.

Grip strength was assessed with a Jamar hand held dynamometer.¹² The testing procedure for evaluating hand grip strength used standardized positioning with either the NK or Jamar grip dynamometers; both were calibrated¹³ Participants were requested to complete three trials of hand grip strength bilaterally with a 15 s time break across the three measurements. The mean of the three trials was calculated. For each trial, participants were seated comfortably in a chair, had their elbow flexed with the forearm and wrist in a neutral position.¹³ They were asked to hold the grip for 2 to 3 s to ensure that the maximum hand grip strength had been achieved.

Statistical analysis

Descriptive analysis was utilized to capture the demographic features of the included sample. Repeated measures generalized linear modeling (GLM) with age and sex as covariates was performed to evaluate the differences in hand grip strength and hand dexterity recovery scores between the injured and uninjured hand at 3, 6, 12 and 24 months after DRF. We conducted normality and Mauchly's Sphericity tests to check if data were normally distributed and our GLM assumptions. Furthermore, an a priori defined minimal clinically important difference (MCID) of ≥ 6.50 kg was used to signify a clinically important difference in grip strength between the injured and uninjured hand.¹⁴ We were unable to define hand dexterity cut-off scores due to a lack of literature. We also calculated the standardized response mean (SRM) to quantify the differences between the injured and uninjured hand in grip strength and hand dexterity at 3, 6, 12 and 24 months after DRF.^15,16 The SRM was used because participants with trauma such as DRF have no baseline data (e.g. pre-trauma grip and dexterity values). Benchmark values for effect sizes of trivial (<0.20), small (≥0.20 to < 0.50), moderate (≥0.50 to < 0.80) or large (≥0.80) were used to estimate clinical relevance.¹⁵ Different plots were also utilized and presented to visualize the recovery of grip strength (extent of recovery to the uninjured side) and hand dexterity across time intervals. Data analysis was done with SPSS software version 23. Significance level was set at alpha ≤0.05.

Results

Demographics

In total, 154 individuals (122 females, 32 males) with a mean age of 53.5 years (SD = 16.2) with DRF were recruited and agreed to participate in the study. In our sample, 90% were right hand dominant. The right hand was injured in 45% of our sample, 53% injured the left hand and 2% fractured both wrists. In total, 73% of the patients reported that they had surgery, 98% were given a cast and 90% received physiotherapy. During the study period, 154 patients completed the grip strength evaluations and 111 patients the hand dexterity assessments. None of the included participants were lost during the follow-up period, although not all performed dexterity testing for a variety of reasons.

Hand grip strength for injured hand

From 3 to 6 months the mean change in grip strength in the injured hand was 6 kg with SRM = 0.6 (moderate). From 6 to 12 months the mean change was 3 kg with SRM = 0.3 (small) and from 12 months to 24 months, the mean change was 1.7 kg with SRM = 0.16 (trivial). Means (SD) of grip strength by age, sex and side are summarized in Table 1.

Table 1.

Hand grip strength by sex and hand side.

Evaluations (months)	Hand side	Sex	Grip strength mean (kg)	SD
3	Injured	Male	24.22	10.83
		Female	13.34	6.80
		Total	15.60	8.94
	Uninjured	Male	41.13	9.26
		Female	24.16	5.56
		Total	27.69	9.46
6	Injured	Male	33.05	12.63
		Female	18.56	6.37
		Total	21.57	9.96
	Uninjured	Male	42.30	9.57
		Female	25.56	7.04
		Total	29.04	10.21
12	Injured	Male	37.80	13.00
		Female	21.16	6.14
		Total	24.61	10.48
	Uninjured	Male	42.68	9.75
		Female	25.01	6.05
		Total	28.68	10.00
24	Injured	Male	39.46	12.78
		Female	22.84	5.90
		Total	26.29	10.31
	Uninjured	Male	43.40	9.79
		Female	24.72	5.79
		Total	28.60	10.18

Hand grip strength differences between injured and uninjured hand

The mean difference in grip strength (kg) between the injured and uninjured hand at 3 months was 12 kg, with SRM= 1.3 (large). At 6 months the mean difference was at 7.4 kg, with SRM = 0.7 (moderate), at 12 months the mean difference was 4 kg with SRM = 0.40 (small) and at 24 months the mean difference was 2.3 kg, with SRM = 0.2 (small). A minimal clinically important difference (MCID) was detected between the injured and uninjured hand at 3 and 6 months (MCID> 6.5 kg) after DRF. The mean differences between injured and uninjured hands and the associated SRM and MCID are presented in Table 2. Recovery plots of adjusted means of hand grip strength are presented in Figure 1(a).

Table 2.

Overall hand grip strength scores (n = 154).

Time (months)	Hand	Grip Strength Mean (kg)	Mean Difference (kg)	95% Confidence interval		Effect Size (SRM)	MCID
Time (months)	Hand	Grip Strength Mean (kg)	Mean Difference (kg)	Lower bound	Upper bound	Effect Size (SRM)	MCID
3	Injured	15.60	12.09	16.85	19.81	1.30	>6.75 kg
3	Uninjured	27.69	12.09	30.96	33.28	1.30	>6.75 kg
6	Injured	21.57	7.47	23.70	26.56	0.73	>6.75 kg
6	Uninjured	29.04	7.47	31.98	34.78	0.73	>6.75 kg
12	Injured	24.61	4.07	27.40	30.32	0.40	<6.75 kg
12	Uninjured	28.68	4.07	32.03	34.53	0.40	<6.75 kg
24	Injured	26.29	2.31	29.15	32.02	0.22	<6.75 kg
24	Uninjured	28.60	2.31	32.27	34.65	0.22	<6.75 kg

MCID: minimal clinically important difference.

Figure 1.

Adjusted means of hand grip strength recovery between (a) injured and uninjured hand, (b) females and males with (c) injured and (d) uninjured hand across 3, 6, 12 and 24 months after the distal radius fracture

Overall, males had better (stronger) grip strength scores compared to females in both hands. For males, at 3 months the mean difference between the injured and uninjured hand in grip strength was 16.8 kg with SRM= 1.6 (large), at 6-months 9.3 kg with SRM= 0.8 (large), at 12 months 4.8 kg with SRM= 0.42 (small) and at 24 months 3.9 kg with SRM= 0.3 (small). For females, at 3 months the mean difference in grip strength) between the injured and uninjured hand was 10.7 kg with SRM= 1.7 (large), at 6 months 7 kg with SRM= 1 (large), at 12 months 3.8 kg with SRM= 0.6 (small) and at 24 months 1.9 kg with SRM= 0.3 (small). A minimal clinically important difference (MCID> 6.5 kg) was detected in grip strength for both males and females at 3 and 6 months after the injury. The recovery of adjusted means of hand grip strength is shown in Figure 1(b) to (d).

Hand dexterity

The largest mean differences in hand dexterity scores between the injured and uninjured hands were observed at 3 months. More specifically, the mean difference between the injured and uninjured hand for large objects was found at 3 months 2.9 s, with SRM = 0.4 (small), for medium objects, was found at 3 months 2.4 s, with SRM = 0.2 (small), and for small objects was found at 3 months 6.4 s, with SRM = 0.4 (small). Overall, the mean differences for all types of objects of hand dexterity between injured and uninjured hand range from small to trivial SRM and are summarized in Tables 3 to 5.

Table 3.

Hand dexterity scores for large objects (n = 111).

Time (months)	Hand	Hand dexterity mean (s)	Mean difference (s)	95% Confidence interval		Effect size (SRM)	MCID
Time (months)	Hand	Hand dexterity mean (s)	Mean difference (s)	Lower bound	Upper bound	Effect size (SRM)	MCID
3	Injured	27.70	2.90	24.93	28.82	0.40	N/a
3	Uninjured	24.80	2.90	23.01	25.42	0.40	N/a
6	Injured	24.80	0.60	23.16	25.55	0.11	N/a
6	Uninjured	24.20	0.60	22.89	24.96	0.11	N/a
12	Injured	25.80	1.40	24.16	27.19	0.22	N/a
12	Uninjured	24.40	1.40	23.21	25.63	0.22	N/a
24	Injured	24.50	0.90	22.94	25.76	0.15	N/a
24	Uninjured	23.60	0.90	22.31	24.49	0.15	N/a

MCID: minimal clinically important difference.

Table 4.

Hand dexterity scores for medium objects (n = 111).

Time (months)	Hand	Hand dexterity mean (s)	Mean difference (s)	95% Confidence interval		Effect size (SRM)	MCID
Time (months)	Hand	Hand dexterity mean (s)	Mean difference (s)	Lower bound	Upper bound	Effect size (SRM)	MCID
3	Injured	40.96	2.46	36.94	42.36	0.22	N/a
3	Uninjured	38.50	2.46	35.37	39.23	0.22	N/a
6	Injured	38.50	1.30	35.67	39.91	0.13	N/a
6	Uninjured	37.20	1.30	34.39	38.11	0.13	N/a
12	Injured	38.70	1.50	36.26	40.64	0.16	N/a
12	Uninjured	37.20	1.50	34.54	37.94	0.16	N/a
24	Injured	39.20	1.50	37.15	41.53	0.15	N/a
24	Uninjured	37.70	1.50	34.74	38.78	0.15	N/a

MCID: minimal clinically important difference.

Table 5.

Hand dexterity scores for small objects (n = 111).

Time (months)	Hand	Hand dexterity mean (s)	Mean Difference (s)	95% Confidence interval		Effect size (SRM)	MCID
Time (months)	Hand	Hand dexterity mean (s)	Mean Difference (s)	Lower bound	Upper bound	Effect size (SRM)	MCID
3	Injured	54.50	6.40	50.66	60.99	0.38	N/a
3	Uninjured	48.10	6.40	46.87	51.16	0.38	N/a
6	Injured	49.00	1.70	46.97	53.27	0.14	N/a
6	Uninjured	47.30	1.70	46.80	50.91	0.14	N/a
12	Injured	49.80	1.80	48.13	54.29	0.13	N/a
12	Uninjured	48.00	1.80	47.19	52.07	0.13	N/a
24	Injured	50.00	2.00	49.06	55.06	0.16	N/a
24	Uninjured	48.00	2.00	47.26	51.29	0.16	N/a

MCID: minimal clinically important difference.

Males had better (faster) hand dexterity scores for the manipulation of large and medium objects in both hands 2 years after the injury. Females had better (faster) hand dexterity for small objects compared to males in both hands across all time points. Recovery plots of adjusted means of hand dexterity are presented in Figures 2 to 4.

Figure 2.

Adjusted means of large objects hand dexterity between (a) injured and uninjured hand, (b) females and males with (c) injured and (d) uninjured hand across 3, 6, 12 and 24 months after the distal radius fracture

Figure 3.

Adjusted means of medium objects hand dexterity between (a) injured and uninjured hand, (b) females and males with (c) injured and (d) uninjured hand across 3, 6, 12 and 24 months after the distal radius fracture[TQ1]

Figure 4.

Adjusted means of small objects hand dexterity between (a) injured and uninjured hand, (b) females and males with (c) injured and (d) uninjured hand across 3, 6, 12 and 24 months after the distal radius fracture.

Discussion

This study demonstrates clinically important deficits in hand grip strength in the injured hand compared to the uninjured hand at 3 and 6 months, and small to trivial deficits in hand grip strength and hand dexterity at 1 to 2 year follow-ups. Grip strength measurements in the injured hand showed continued improvements of 50% between time intervals.

The largest deficit in grip strength between the injured hand and uninjured hand (mean difference 12 kg) was recorded at 3 months. Even at 6 months post-injury, the deficit was clinically important when comparing the injured and uninjured side. Since a loss of grip strength is expected due to pain and immobilization, grip strength can chart the recovery of neuromuscular function. Improvements in motor control, reduction in pain, resumption of functional activities that would strengthen the grip strength muscles are expected to contribute to this recovery. Other researchers have examined grip strength recovery after DRF.^17–20 Two of the studies^19,20 that examined the recovery of grip strength reported ongoing recovery of grip strength occurred up to 1 year. Lee and colleagues¹⁸ found that grip strength at 6 months averaged 65% of the injured side. Porter¹⁷ reported that grip function was close to normal after 6 months; however, grip function was assessed with the Sollerman Hand Function test and not with a handheld dynamometer. The sample size for all the previous studies ranged from 22 to 70 participants. The general conclusions of our study are similar to those, although we had a larger sample which might facilitate finding significance of smaller differences.

Hand dexterity deficits between the injured and uninjured hand for all types of objects ranged from small to trivial effect sizes at 2 years after the DRF. We used SRM to indicate the magnitude of the effect because clinically important differences for dexterity tests have not been defined. However, this is an imprecise way to estimate the clinical relevance, and we cannot be certain if the differences in hand dexterity are meaningful to patients. The largest mean difference between the injured and uninjured hand was detected in small objects hand dexterity at 3 months. A primary finding is that our first-year results on hand dexterity measurements even with significantly smaller sample size (n = 111) are similar to a recent 1 year prospective cohort study that used the NK hand dexterity device with a larger sample size (n = 242).²¹ A secondary finding is that hand dexterity for large objects of the injured hand improved from 1 year to 2 years; however, for medium and small objects hand dexterity worsened. This is an indication that probably fine motor movements are affected the most after DRF and continued to worsen from 1 to 2 years’ post-injury.

We expect that the lack of clinically important differences in dexterity at the later phases reflect smaller improvements and some loss of the learning of how to do the test since most patients would have been discharged and no longer attend therapy sessions where such tests might be incorporated. Some of the elements of the NKHDT require a specific motion pattern to move the object and with longer intervals between testing this memory may have been lost. Testing methods where a practice trial is provided and the score discarded might reduce the impact of such learning on scores. Reductions in swelling and pain, combined with improvements in motion and grip strength would contribute to better hand dexterity. A recent clinical study²² has found that dexterity scores on the NKHDT can be explained 34% by grip strength and range of motion scores at 6 months after DRF. The paucity of the literature around hand dexterity and the use of NK dexterity test make it difficult to compare our results with other studies.

Furthermore, caution is advised in interpreting statistically significant differences as being clinically important when the number of participants in a study is large. In our study, we detected statistically significant differences (p < 0.001) for the differences in grip strength and hand dexterity between injured and uninjured hand at 3, 6, 12 and 24 months. However, our SRM calculations indicated that the deficit between injured and uninjured side in grip strength and hand dexterity recovery were small to trivial between 1 year and 2 years after fracture. Grip strength differences still existed between the injured and uninjured side at the 1 year and 2 year follow-up after DRF. However, based on Kim et al.’s (2014) study, the differences were too small to be clinically important.¹⁴ Therefore, deciding whether the differences are clinically important on the basis of numbers alone is open to classification errors.

Strengths of this study included that we assessed and compared both grip strength and hand dexterity (large, medium, small) recovery between injured and uninjured side in a large cohort of patients at 3, 6, 12 and 24 months while controlling for age and sex. Despite this, caution should be used when interpreting our findings. Our sample was predominantly female. While this is consistent with the DRF patient population, it means that our findings may not be as generalizable to men. Furthermore, we did not consider several factors that may affect our results, such as hand dominance. However, almost 45% fractured their dominant side and we believe this was a well-balanced distribution in our sample. Differences of up to 11% in grip strength have been reported in the literature when comparing the dominant side with the non-dominant side.²³ Despite the male underrepresentation, our study concurs with others that show males have higher grip strength than females.²⁴ Regarding hand dexterity, a potential limitation that may affect the scores is the participants’ visual acuity, which was not measured or controlled for. The NKHDT and other functional tests presume that speed of movement is a good indicator of hand function, yet other factors like quality of movement and types of tasks that can be performed may be more important to patients. A benefit of the NKHDT is that it assesses different sized objects, but a major drawback is that the device has been discontinued and therefore, it is unlikely that these data will be comparable in the future.

Future implications

The knowledge that clinically important differences in grip strength recovery between the injured and uninjured hands after DRF may persist for up to 6 months, would allow clinicians to plan a rehabilitation program to improve strength and inform patients of the need for continued strength building activities after discharge from therapy. Furthermore, it would allow clinicians to set valid rehabilitation goals to improve patient outcomes. This study also indicates that hand dexterity remains impaired up to two years following a DRF, although we do not know if these differences are clinically important or not. Current clinical practice guidelines do not address dexterity assessments and treatment after DRF and there is a need for further research to provide evidence-based strategies for optimizing hand dexterity recovery.

Conclusions

There were clinically important differences in grip strength recovery between the injured and uninjured hands after DRF at 3 and 6 months’ follow-up. However, at 12 and 24 months, grip strength differences are small and may not be clinically important. Furthermore, we found trivial to small impairments in hand dexterity (small, medium large) recovery comparing the injured and uninjured hands 2 years after DRF.

Footnotes

Acknowledgements

We would like to thank Katrina Munro and Joshua Vincent for their significant assistance in the data collection. Their contribution was valuable to complete this work.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: PB and GN were supported by Western Graduate Research Scholarships (WGRS) from Western University in London, Ontario, Canada. JM was supported by a CIHR Chair in Gender, Work and Health and the Dr. James Roth Research Chair in Musculoskeletal Measurement and Knowledge Translation. The study was supported by Canadian Institutes of Health Research (FRN: 122070).

Ethical approval

Ethical approval was granted by Western University institutional research ethical board (FN: 5697) according the World Medical Association Declaration of Helsinki.

Informed consent

Written informed consent was obtained from the patient(s) for their anonymized information to be published in this article.

Contributorship

BP researched literature and conceived the study. RG, JM, EL and GN was involved in protocol development, gaining ethical approval, patient recruitment and data analysis. GN and PB wrote the first draft of the manuscript. All authors reviewed and edited the manuscript and approved the final version of the manuscript.

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