Functional outcome after corrective osteotomy for malunion of the distal radius: a randomised, controlled, double-blind trial

Distal radius fracture is the most common injury in the orthopaedic emergency room [1]. A common complication of initially displaced and reduced distal radius fractures is healing with malunion [2]. This is reported to occur in approximately 35% of non-surgically treated fractures and up to 10% of surgically treated fractures [3, 4]. A malunion may cause pain and reduced range of motion (ROM) and may thereby hamper the ability to perform activities of daily living, take part in activities during leisure time or manage the demands of work [5, 6].

Corrective osteotomy is a surgical procedure that aims to ameliorate function by restoring the anatomy of the wrist. Various methods for performing this surgery have been described. Clinical symptoms, such as pain, reduced grip strength and reduced range of motion (ROM), rather than radiographic appearance, determine whether surgical intervention is indicated [7]. The procedure involves the re-creation of the fracture at or near the healed fracture site. The distal radius fragment is reduced until the radiographic appearance of the distal radius, the ulna and the carpal bones is normalised as effectively as possible [8]. Open-wedge osteotomy with plate fixation is regarded as the standard procedure for the common dorsally displaced Colles’ fracture [9]. It effectively restores the length of the radius, but, at the same time, it creates a void and grafts are often used to fill the void to create better stability [10]. An autograft from the iliac crest is often used, but this may lead to pain and other complications at the donor site [11]. To reduce complications of this kind, the use of a synthetic bone substitute is an option [12, 13], while leaving the void open is another option [14].

Previously, evaluations after different orthopaedic injuries, such as distal radius fractures, focused on radiological aspects and functional outcome in terms of grip strength and range of motion. In recent decades, the importance of taking the patients’ experiences and well-being into account, using different patient-rated outcome measurements (PROMs), has been emphasised [15]. This adds aspects that are likely to be of major relevance to the patients.

In a previous review of studies presenting results from surgery both with and without grafts, some of the studies included evaluations of subjective outcome, such as patient-rated wrist function and pain. This review indicated that the use of grafts was not necessary, either with respect to PROMs or with regard to regained function or radiographic outcome [16]. A recent, retrospective study, comparing the results of osteotomies, with or without the use of grafts, also indicates no differences in functional outcome between the methods [17]. Since corrective osteotomy is a relatively rare procedure, studies are often small, and more studies, including randomised, controlled studies, comparing functional outcome when a graft is or is not used, are needed.

The purpose of this study was to evaluate functional outcome during the first year after corrective osteotomy for malunited distal radius fractures, with or without filling the osteotomy void.

This randomised, controlled, double-blind trial comprised a series of patients undergoing osteotomy because of a malunited distal radius fracture between December 2014 and May 2018 (Fig. 1). The study was conducted on the Mölndal campus at Sahlgrenska University Hospital in Sweden. The indication for osteotomy was a malunion after a non-surgically treated distal radius fracture that was determined radiographically, in patients suffering from pain and functional limitations affecting their ability to perform activities of daily living.

The malunion warranted surgery if there was a dorsal tilt of > 20° with or without one or more of the following parameters:

The exclusion criteria were dementia or not being able to communicate in Swedish without an interpreter. It was the surgeon who invited participants to the study after the pre-operative examination. After enrolment in the study, the patients visited the first author, who is an occupational therapist, and received both oral and written information about the study and the patients who chose to participate gave their informed, written consent. A total of 69 patients were assessed for eligibility, 11 did not meet the inclusion criteria, two were missed at inclusion, four declined to participate and eight decided not to undergo surgery. Recruitment started in December 2014 and follow-up was completed in May 2019. The study was performed in line with the principles of the Declaration of Helsinki and approved by the Ethics Committee in Gothenburg, Sweden (no. 472-14) and registered in a local register at Sahlgrenska Hospital (no. 29934). At the time the study began, it was not a prerequisite to register studies elsewhere.

The osteotomy was performed as a dorsal open-wedge distal radius osteotomy, which was fixed with a volar locking plate, using a two-incision procedure. The plate that was used was a DiPhos R Plate (Limacorporate, Udine, Italy), made of carbon fibre and PolyEtherEther Ketone polymer (PEEK), which is radiolucent [18, 19]. During the first year of the study, a narrower variant of the plate, DiPhos RM, was introduced to provide a better fit in patients with a thinner skeleton. The DiPhos RM Plate was used in four patients in the treatment group and in six patients in the control group.

The patients were randomised during surgery, by a person independent of the study, using the “Randomizer” app [20]. The ratio between the groups was 1:1. The treatment group had the osteotomy filled with HydroSet, a synthetic bone cement consisting of hydroxyapatite (HydroSet, Stryker Liebinger GmbH& Co. KG, D-79111 Freiburg, Germany), whereas the void was left empty in the control group.

There were no significant differences between the patients completing the study, compared with the drop-outs in terms of age (p = 0.38), gender (p = 0.23) or injury to the dominant hand (p = 0.36).

The treatment group and the control group each comprised 15 women and four men.

The mean age in the treatment group was 59 (SD13) years and 55 (SD16) years in the control group. There was no statistically significant difference in terms of age between the groups (p = 0.32). In the treatment group, one patient, who was injured during childhood, underwent surgery 336 months (28 years) later. For the other patients, the range was 4 to 65 months from injury to surgery. Demographic data for both groups are shown in Table 1.

The results of this randomised, controlled, double-blind trial of 38 patients indicate that there were no significant differences in terms of functional outcome between the treatment group, in which the patients had the osteotomy void filled, and the control group, in which the void was left empty. There were no significant differences between the groups at any time point post-operatively in terms of any of the PROMs used, for either range of motion or grip strength.

The results of this study indicate that osteotomy after the malunion of a distal radius fracture improves self-perceived ability to perform activities, range of motion and grip strength. The functional outcome in this study is comparable with the results in another recent study comparing outcome for patients initially treated surgically and patients treated with reduction and a cast after comminuted distal radius fractures [35].

The PRWE, the Q-DASH and COPM satisfaction scores had improved significantly 12 months post-operatively compared with pre-operatively for both groups. The minimal clinically important difference (MCID) can be defined as “the smallest change in an outcome perceived as beneficial by patients” [36‐38]. The improvement in the PRWE score from a median of 58 points to 14 points in the treatment group and from 58 points to 20 points in the control group exceeded the MCID, which is 11 points in patients with distal radius fractures [34]. The PRWE pain score decreased from 28 (95% CI 21–41) to 9 (95% CI 6–20) (p < 0.05) in the treatment group and from 29 (95% CI 21–33) to 17 (95% CI 6–24) (p < 0.05) in the control group. These improvements also exceeded the MCID, which is 1.5 points for the PRWE pain scale, in patients with distal radius fractures [34]. Earlier research has shown that the functional outcome one year after a distal radius fracture is associated with a reduction in pain [39]. The results of this study indicate that, from the patient’s perspective, it is worthwhile undergoing surgery, since the improvement in both the PRWE scores and the PRWE pain scores was not only statistically significant but also exceeded the MCID 12 months post-surgery, compared with before (Fig. 8).

The results in terms of the RAND-36 indicate no differences pre-operatively to 12 months post-operatively, apart from an improvement in “role physical” and “bodily pain” in the treatment group. It is expected that health-related quality of life will not change that much in one year in this patient group, since they are not suffering from a progressive disease. An interpretation of the results is that the improvement in the wrist, which is reflected in the improvement in the PRWE and Q-DASH scores, is not reflected in the health-related quality of life in the way that it is evaluated using the RAND-36.

With respect to range of motion, the pattern of recovery was similar over the year in both groups. Dorsal extension was not significantly decreased compared with the non-injured side pre-operatively in either group, nor did it change significantly over the year. All other movement directions were significantly decreased in the injured wrist pre-operatively compared with the non-injured side. Volar flexion was the movement direction that was mostly decreased pre-operatively compared with the healthy side in both groups, and was the movement direction where the largest recovery was seen. However, also pre-operatively, both groups had enough capability in volar flexion to manage activities of daily living. About 40° of wrist flexion has been shown to be sufficient for activities in daily life [40]. The improvement in radial and ulnar deviation was probably too small to be noticeable for the patients. The changes in supination, pronation and volar flexion were large enough for the patients to detect. Taken one by one, the changes are probably not clinically important, but the sum of all the changes together is, as the total range of motion arc increased, enabling the wrist to function more effectively in everyday life activities. For the control group, the recovery in range of motion was so large that there were no longer any differences compared with the non-injured side in supination, pronation and radial and ulnar deviation. Moreover, in the treatment group, the recovery was also large enough for the patients to reach range of motion close to the values on the non-injured side and, again, there were no significant differences between the groups.

Concerning grip strength, there was a significant increase at the 12-month follow-up in both groups compared with pre-operatively. The change was large enough to presume that it was noticeable for the patients in both groups, which is clinically important, since the recovery of grip strength is important for the ability to perform activities of daily living [41]. The recovery, in terms of increased range of motion and grip strength, was reflected in the PROMs.

The results of this study indicate that the use of a bone substitute does not appear to imply any significant advantage as analysed by any of the PROMs used, or in terms of range of motion or grip strength. This finding is in line with the result of a recent study by Mugnai et al. [16], comparing the use of an iliac bone graft with a non-graft, with respect to time to healing and functional outcome. It revealed that osteotomies of extra-articular malunions do not require grafting when a volar locking plate is used [16]. Another recent study of 48 patients also revealed that there was no difference in functional outcome regardless of whether or not a graft was used [17]. Since there is a cost associated with using a bone substitute, surgeons should consider the possibility of not filling the void. In the present study, the osteotomies were carried out with the preservation of volar cortical contact, thereby facilitating healing. If osteotomy gaps are larger, a bone substitute or other grafts might, however, be necessary to maintain stability and facilitate bone healing.

There were some limitations to this study. During the time of the study, a narrower plate was introduced because the original plate appeared to be too wide to be suitable for patients with a thinner skeleton. The narrower plate was used in ten patients (four in the treatment group and six in the control group). It is possible that the change of plate affected the outcome of the trial. No calculations were made with respect to which kind of plate was used.

Another limitation is that five patients (two with the original plate in the control group and three with the narrower plate, of which two were in the treatment group and one in the control group) suffered an implant failure during the first year post-surgery. Because of the implant failure, they were excluded from the analysis.

In this trial, interest focused on functional outcome from the patient’s perspective. The results with respect to radiology, such as time to healing, remaining deformities and the occurrence of osteoporosis, are not presented or linked to functional outcome, which might be regarded as a limitation.

One strength in this study is that the surgery was performed by one surgeon. Other strengths are that the measurements were made by one, blinded, occupational therapist, with just a few exceptions when they were made by two other trained occupational therapists, and that the measurement methods and PROMs that were used have been tested for validity and reliability.

There is no significant difference in functional outcome during the first year after corrective open-wedge distal radius osteotomy, where cortical contact is maintained, regardless of whether or not a bone substitute is used to fill the void.