Comparison of volar locking plates with external fixation and K-wires in arthroscopically assisted intra-articular distal radial fracture fixation

Abstract

This article presents the results of a prospective cohort study that included 63 patients with intra-articular (AO Type C) distal radial fractures who were treated using an arthroscopically assisted approach with either volar locking plates or external fixator and K-wires. Postoperative analysis was carried out using X-ray assessment, clinical data, Patient-Rated Wrist Evaluation score, Gartland and Werley score, Modern Activity Subjective Survey of 2007 score, range of motion, grip, pinch and tripod pinch assessment at 1, 3, 6 and 12 months postoperatively. Despite the statistically significant differences found in a number of parameters during the period of observation, there were no clinically relevant differences determined between the two methods. There was a greater number of complications in the external fixator and K-wire treated patients.

Level of evidence: II

Keywords

Intra-articular distal radial fracture wrist arthroscopy volar locking plate external fixator K-wire fixation

Introduction

The increasing incidence of distal radial fractures may be attributed to an ageing population, as well as the growing participation in outdoor pursuits of the younger population that leads to high-velocity accidents (Shukla et al., 2014). Approximately 32% of fractures nowadays are AO Type C fractures (Koo et al., 2013).

There are many articles which claim that superior outcomes are achieved as a result of anterior plating of distal radius fractures (Esposito et al., 2013; Franceschi et al., 2015; Richard et al., 2011; Wilcke et al., 2011; Williksen et al., 2013; Wright et al., 2005; Xie et al., 2013) and others which claim that external fixation and K-wires are superior (Kapoor et al., 2000; Pino et al., 2011). Arthroscopic reduction of intra-articular fragments, as opposed to conventional methods, may improve outcomes regardless of the method of fixation, volar locking plates or external fixator and K-wires (Abe, 2014; Doi et al., 1999; Freeland and Geissler, 2000; Ono et al., 2012; Ruch et al., 2004; Varitimidis et al., 2008).

This article presents a prospective comparison of outcomes of the two methods of fixation, both in combination with arthroscopically assisted reduction of intra-articular fragments.

Methods

The study protocol was approved by the local ethical committee. Patients were recruited between May 2015 and May 2017 throughout several regional emergency trauma centres. The inclusion criteria were an intra-articular distal radial fracture (AO Type C), a closed epiphyseal plate and willingness to undergo hand therapy in our rehabilitation centre. The exclusion criteria were patients with polytrauma, bilateral or open fractures, previous fractures or concomitant fractures of the same upper extremity.

Surgical technique

All surgeries were carried out by two senior orthopaedic surgeons, experienced in wrist arthroscopy. Surgeries in both groups were performed under axillary block or general anaesthesia and with the tourniquet inflated to between 280 and 320 mmHg. The volar locking plate group (Group VLP) surgeries were performed using the flexor carpi radialis approach and pronator quadratus muscle elevation. Fracture fixation was achieved with two different plates: Synthes 2.4 mm locking compression plate (LCP) distal radius system or Stryker VariAx plate. Once the fracture was preliminarily fixed with the plate, the wrist joint was assessed arthroscopically using the 3-4 and 4-5 portals. In several cases additional portals, 6U and 1-2, were used to remove blood clots and small articular fragments. If articular step-offs or gaps were present, additional reposition and fixation with K-wires were performed. Distal screws were inserted only after arthroscopic inspection of the radiocarpal joint and a fluoroscopic confirmation of the correct position for the screws. If dorsal, ulnar or radial fragments, uncontrolled by the plate, were detected, additional K-wires were inserted. These were cut under the skin and remained indwelling after the procedure. Associated soft tissue injuries, such as triangular fibrocartilage complex (TFCC) tear, damage of scapholunate or lunotriquetral ligaments, were assessed after the fracture had been stabilized. In several cases, debridement of the injured ligaments or TFCC was performed, as well as trans-articular fixation of the scapholunate and/or lunotriquetral joints with K-wires, or application of peripheral sutures for TFCC tears. Bone-grafting was not performed.

The external fixator and K-wire group (Group EF) surgeries commenced with a primary closed reduction and fixation with several K-wires, under fluoroscopic guidance. Following fixation in a traction tower, the articular surfaces were assessed using the same arthroscopic technique as for Group VLP. Further fragment reductions were performed, if required, using a probe or K-wires as joysticks through elongated 3-4, 4-5, 1-2 and in some cases, volar portals. Additional K-wire fixation was used as required. At this point, associated soft tissue injuries were assessed and additional procedures were performed as for Group VLP, when necessary. Once satisfactory reposition was achieved, the bridging external fixator was applied. Both Synthes Small External Fixator and Stryker Hoffmann II Compact External Fixator were used. The wrist was released from the traction, K-wires were cut under the skin and the wounds were closed with simple interrupted sutures.

All arthroscopically assisted surgeries were performed using the dry arthroscopy technique recommended by Francisco del Piñal (Del Piñal, 2011).

Postoperative care

Patients in Group VLP were treated with a short plaster cast for 2 weeks, followed by a removable short arm orthosis for approximately 2 weeks, when gentle active wrist motion could begin. For Group EF patients, the external fixator was removed 4 weeks after surgery. K-wires were usually removed between 4 and 6 weeks after surgery. Patients were advised to use a removable orthosis, if required. Standard exercises for finger motion were initiated immediately after the surgery for both groups. The first visit to the same hand therapist was scheduled for all patients 2 weeks after the surgery. All patients were instructed to perform additional exercises at home for a minimum of 30 minutes per day and visit a hand therapist on a weekly basis. Patients were recommended to use nonsteroidal anti-inflammatory drugs during the first week after the surgery and as required thereafter.

Assessment

This was a prospective cohort study, where patients were allocated into two groups using an alternative allocation method, the first patient undergoing surgery with VLP, the second one with an external fixator and K-wires, the third one with VLP and so on. The results of treatment were assessed with X ray examinations postero-anterior position in a 10° tilted-view and lateral position in a 20° tilted-view, subjective evaluation using the Patient-Rated Wrist Evaluation (PRWE) score (rating from 0 to 140, with a lower score representing a better result), Modern Activity Subjective Survey of 2007 (MASS07) score (rating from 0 to 100, with a lower score representing a better result), and subjective and objective evaluation using the Gartland and Werley score (rating from 17.5 to 100, with a higher score representing a better result). Grip/pinch/tripod-pinch strength and range of motion (ROM) were also measured. Wrist mobility was tested using a goniometer, grip strength with Jamar dynamometer, and pinch and three-point strength with a pinch gauge. Scheduled follow-up assessments were performed at 1, 3, 6 and 12 months postoperatively by a hand therapist or by one of the senior orthopaedic surgeons if the hand therapist was not available. X-ray assessment was performed by an independent radiologist as the Gartland and Werley score includes a radiological assessment of fracture consolidation and ulnar variance.

Statistical analysis

A sample size calculation showed that 26 individuals in each group would provide 80% power (with alpha 0.05) for strength and ROM measurements compared with a healthy hand. That decided our sample sizes of the two groups. Mean values and standard deviations were calculated in descriptive statistics. Chi-square tests revealed the equality of the research groups. Normality of data was checked with the Shapiro–Wilk test, the Mann–Whitney U test was applied for non-parametric data and an independent sample T test was used for parametric data.

Results

During the 2-year study period, 74 surgeries were performed (38 VLP and 36 Group EF). Four patients in Group VLP and seven patients in Group EF did not return for follow-up and thus were excluded from the analysis. Consequently, only 34 patients from Group VLP and 29 patients from Group EF were included in the final data assessment. Of the 63 patients, there were 23 males, mean age 43 year (range 19–66) and 40 females, mean age 56 years (range 29–73). The demographic and clinical data were comparable between the groups (Table 1).

Table 1.

Characteristics of patients in two groups.

Patient information	Group VLP	Group EF
Number of patients	34	29
Gender: M/F	11/23	13/16
Age, years (SD)	56 (12)	53 (12)
Injured hand: right/left	9/25	11/18
AO type
C1	12%	8.0%
C2	29.%	20 %
C3	59%	72%
High velocity of trauma	2	1
Presence of ulnar styloid fracture	47%	63%
Presence of ligament injury	50%	66%

AO: Arbeitsgemeinschaft für Osteosynthesefragen; M: male; F: female; Group VLP: volar locking plate group; Group EF: external fixator and K-wire group.

The frequency of ligament co-injury did not statistically significantly differ between the two groups (p = 0.22). Sixteen patients had scapholunate ligament tears (Geissler grade II–IV), 11 patients had TFCC tears and eight patients had both. Scapholunate joint trans-fixation with K-wires with additional scaphocapitate joint fixation was performed in nine patients with acute Geissler grade IV scapholunate ligament tears. Seven patients from both groups underwent ulnar styloid fracture fixation with K-wires and tension bands due to TFCC and distal radioulnar joint instability.

Additional reduction of fracture fragments at arthroscopy was necessary in 46 cases, 20 patients (59%) in Group VLP and 26 patients (90%) in Group EF (p = 0.006).

The clinical parameters (ROM and strengths) as well as subjective scores (PRWE, MASS07 and Gartland and Werley) improved evenly during the 12 months following surgery, showing a small superiority in figures for the patients of Group VLP (Table 2). There were statistically significant differences in a number of goniometric and dynamometric measurements at particular times during the period of observation. However, other than the results at 1 month, these differences were not found to be consistent at each review time (Table 2). Further, the clinical relevance of these differences between the groups is open to discussion.

Table 2.

Percentage wrist motion and strengths of the contralateral normal hand and their comparisons between two patient groups at different postoperative time-points.

ROM or strengths	Month 1	Month 3	Month 6	Month 12
Supination
Group VLP, %^a	56	88	93	97
Group EF, %	40	79	89	90
P value	0.006	0.03	NS	0.008
Radial deviation
Group VLP, %	41	76	83	90
Group EF, %	27	64	75	83
P value	0.012	0.022	NS	0.021
Extension
Group VLP, %	46	74	87	92
Group EF, %	24	76	82	88
P value	0.00	NS	NS	NS
Grip strength
Group VLP, %	29	62	81	87
Group EF, %	11	55	71	83
P value	0.00	NS	0.008	NS
Key pinch
Group VLP, %	45	79	87	91
Group EF, %	29	77	88	91
P value	0.007	NS	NS	NS
Tripod pinch
Group VLP, %	39	75	87	92
Group EF, %	25	71	87	93
P value	0.035	NS	NS	NS

Percentages shown in the table are those compared with the contralateral hand.

Group VLP: volar locking plate group; Group EF: external fixator and K-wire group; NS: no significant difference.

There were no statistically significant differences in Gartland and Werley scores and MASS07 scores between the groups (p = >0.05). The PRWE pain and function score showed statistically significant differences only at 1 month, 52 points in Group VLP and 74 points in Group EF (p = 0.001). The MASS07 and PRWE scores showed better results for patients with a non-dominant hand injury compared with the patients with a dominant hand injury.

Complications

Two out of 29 (7%) patients in the Group EF sustained iatrogenic injury to the sensory branch of the radial nerve, requiring further surgery (Table 3). One female patient of 34 patients (3%) in the Group VLP developed a complex regional pain syndrome. The patient was successfully treated conservatively by physical therapy and appeared symptom-free within 6 months after surgery. Three out of 34 patients (9%) in the Group VLP experienced minimal migration of K-wires and skin irritation. This complication was minor and did not require any secondary manipulation. Two patients of 29 (7%) in Group EF suffered a minor loss of reduction of fragments following removal of the external fixator and K-wires. It was discovered at the 3-month follow-up X-rays and also did not require secondary surgery.

Table 3.

Incidence of complications in Group VLP and Group EF.

Complication	Group VLP (n = 34)	Group EF (n = 29)	All study population (n = 63)
CRPS	1 (3%)		1.6%
Iatrogenic nerve injury		2 (7%)	3.2%
Loss of reduction after pin removal		2 (7%)	3.2%
K-wire migration	3 (9%)		4.8%
Total	4 (12%)	4 (14%)

Group VLP: volar locking plate group; Group EF: external fixator and K-wire group; CRPS: Complex Regional Pain Syndrome.

Despite these complications, all patients showed good or excellent scores on completion of the PRWE, Gartland and Werley and MASS07 questionnaires at 12 months after the primary surgery.

Discussion

Despite the statistically significant differences found in a number of parameters during the period of observation, we found there were no clinically relevant differences determined between the two methods. Group VLP showed superior short-term results for functional recovery, although there were no clinical differences in all aspects between both groups at 12 months after surgery. All differences at 1 month are explained by the fact that an external fixator was removed after 4 weeks of immobilization and for some patients K-wires remained indwelling longer. Given that it is possible to start early motion after volar plating, it is noteworthy that the patients of Group VLP were able to return to normal daily activities more quickly.

Subsequent alternating statistically significant differences in some aspects of the ROM values could be the result of the inconsistency of measurements performed by three different people. Regardless of these statistically significant differences, the clinical relevance of these differences is questionable (e.g. 90% against 97% of normal supination at 12 months). Our conclusion is that we were unable to demonstrate any clinically relevant differences in any measured parameter between the two groups, except at 1 month.

The possible cause of damage to the dorsal radial nerve was the extensive use of K-wires during the primary surgery or application of several K-wires via the 1-2 portal during the arthroscopically assisted manipulation, reposition and fixation of fragments. This suggests that the more extensive use of K-wires in reduction and/or fixation during external fixation and K-wire fixation is more likely to result in nerve damage.

Both methods of fixation were relatively easy to apply for AO Type C1 fractures. However, surgery for the more complex AO Type C3 fractures was much more difficult, regardless of the method of reduction and fixation. The higher rate of reposition of fragments at arthroscopy suggests that it is more difficult to obtain optimal reduction in complex fractures with four or more articular fragments when they are treated with external fixation and K-wires. Also, primary reduction and fixation with several K-wires does not guarantee the stability of the extra-articular alignment of the fragments to the same extent as a volar locking plate. Furthermore, the complication of subsequent loss of position of fragments also occurred in two of the Group EF patients.

The place of arthroscopy in this trial deserves a little further consideration. Our results using arthroscopy to visualize fragment position following preliminary reduction confirm the worth of this method in the treatment of these fractures. Fluoroscopy alone provides an image that has poorer resolution than that of the magnified camera used for direct arthroscopic visualization, whereas even a small degree of displacement is obvious arthroscopically (Lutsky et al., 2008). Edwards et al. (2001) performed arthroscopic examinations of the radiocarpal joint after closed reduction and percutaneous pinning in 15 patients. They found an articular displacement of 1 mm or more in 33% of their patients. More severely comminuted and higher energy injuries are more likely to require readjustment (Auge and Velazquez, 2000). Our incidence of reposition of fragments at arthroscopy was higher than found in the literature. Despite the increased need to perform this in Group EF patients, our Group VLP patients also underwent this procedure more frequently than previously reported (Abe and Fujii, 2017; Burnier et al., 2018; Khanchandani and Badia, 2013; Ono et al., 2010, 2012).

This study has a number of limitations. Alternate allocation was chosen as a method of randomization in order to achieve a similar number of patients in both groups as soon as possible. In some cases, this method of allocation made it difficult to fix fragments optimally. The surgeon may have preferred to adapt the technique according to the complexity of the fracture type. In some Group VLP patients, additional K-wire fixation for free fragments was necessary, but not in others.

Some patients failed to return for follow-up visits, so we were unable to assess their outcomes. The reasons for the lost follow-up included unwillingness to continue participation in the study, living too far from the hospital and other unspecified reasons. In several cases, the follow-up of patients was carried out by the same surgeon who had performed the surgeries.

However, all surgeries were performed by experienced surgeons, rather than trainees or residents, and postoperative care was provided by one physiotherapist who used an equal approach of treatment for each patient. Both groups were demographically well balanced. We excluded the possibility of choosing the method of fixation based on patient age or the comminution of the fracture, so we assessed a mixture of both young and old patients with a mixture of fracture types, treated with external fixation or VLP fixation. The outcomes do not establish absolute evidence for preference of one fixation method over the other. There was an increased complication rate with the external fixator and K-wire method.

Footnotes

Declaration of conflicting interests

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

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

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