When reviewed, literature reveals no consensus on management algorithm of unstable DRF in elderly populations. Different options of surgical approaches, fixation methods and graft materials have been described reporting debatable outcomes [1,2,3,4,5,6,7].
Of these controversial options is augmentation of DRF fixation with synthetic bone substitutes. Indeed, the latter option has gained increasing popularity among orthopedic surgeons because of its potential mechanical and biological advantages. However, there is still no robust evidence of superiority of bone substitutes-augmented fixation of DRF compared with its non-augmented counterpart [4,5,6].
Based on this debate, the current study was conducted to investigate the following questions; (1) “Do bone substitutes contribute effectively to postoperative stability of K-wire fixation construct of elderly unstable distal radius fractures?” and (2) “Do bone substitutes accelerate healing of elderly unstable distal radius fractures?”; assuming that bone substitutes-augmented percutaneous pinning is to show significantly higher primary stability of the fixation construct and shorter duration for fracture healing.
Outcomes of the study
“Do bone substitutes contribute effectively to postoperative stability of fixation construct of elderly unstable distal radius fractures?”
The most important finding of the present study was that use of bone substitutes for augmentation of percutaneous pinning of elderly unstable DRF didn’t significantly add to mechanical stability of the fixation construct; this finding can be clued from statistically-comparable secondary displacement of postoperative radiographic parameters between studied groups. Figs.
8A, B, C, D, E, F and 9A, B, C, D, E, F demonstrate insignificant secondary displacement of postoperative radiographic parameters of augmented and non-augmented percutaneous pinning of DRF respectively.
The preceding finding is also reported by other authors utilizing a different fixation method of DRF; i.e. plating. In a prospective randomized trial of dorsally-plated comminuted elderly DRF allocated into two groups (i.e. bone substitute-augmented group of 19 patients and non-augmented group of 20 patients); Jakubietz et al showed 1-year postoperative insignificant differences in functional scores and radiographic parameters between groups with better ROM and grip strength in non-augmented group; pointing out that no clear mechanical advantages of added granular bone substitutes could be concluded [4].
In a cohort study investigating role of bone substitutes in maintaining DRF reduction through comparing radiographic parameters of non-augmented versus hydroxyapatite bone substitutes-augmented volar plating of elderly unstable DRF; Goto et al stated that there were insignificant differences (except for ulnar variance) between groups [10].
On the other hand, currently-reported insignificant mechanical advantages of bone substitutes might be contradicted by recommendation of Hedge et al who advocated bone substitutes-augmented percutaneous pinning in a prospective case series (i.e. no control group) of 27 elderly DRF; reporting insignificant marginal changes in radiographic parameters at 16-week postoperative follow-up [5].
In addition, another contradiction might be inferred from a cadaveric study (including 28 fresh-frozen cadavers) of Kainz et al who elaborated significantly-improved mechanical properties (e.g., decreased displacement and increased stiffness under cyclic loading) of injectable hydroxyapatite bone substitutes-augmented volar plate fixation of simulated AO/OTA type-A3 distal radius fractures compared with non-augmented plating [11].
In the current study, the sole significant difference in radiographic parameters between the studied groups (i.e., significantly less secondary displacement of intra-articular step-off in the augmented group) might favor presumed advantage of structural support of the bone substitutes in management of DRF. However, this radiographic difference didn’t result in significant clinical differences (i.e., in terms of ROM and functional scoring systems) between the studied groups. Up to date, correlations of postoperative radiographic parameters of DRF with long-term functional outcomes and post-traumatic osteoarthritis have not been well established [1, 4, 12,13,14,15].
In a retrospective review of 51 patients of unstable intra-articular DRF managed with volar locked plating; Dario et al stated that radiographic parameters of significant correlation with 3-year postoperative ROM and functional outcomes were ulnar variance and volar tilt rather than intra-articular step-off [12].
Meanwhile, in a randomized controlled trial of 73 elderly patients (age: ≥ 65 years) of unstable DRF assigned between a group of volar plating (36 patients) and a second group of closed reduction and casting (37 patients); Arora et al reported that by 6th and 12th postoperative months, radiographic parameters were significantly better in plated fractures; however, this better radiographic reduction did not result in significantly superior ROM and functional outcomes compared with conservatively- managed fractures [1].
In systematic review of 21 studies of 5 different management modalities of elderly unstable DRF, Diaz et al concluded that despite cast immobilization following closed reduction showed the worst radiographic parameters; however, it had indifferent functional outcomes and the lowest complication rate compared with operative options (e.g., percutaneous pinning, volar locked plating and birding and non-bridging external fixators) [15].
“Do bone substitutes accelerate healing of elderly unstable distal radius fractures?”
Another important finding of the current study was that bone-substitutes augmentation of elderly unstable DRF pinning might insignificantly delay fracture healing. This finding could be explained by loss of fracture hematoma during surgical dissection for impaction of the bone substitutes. In addition, healing of all fractures in non-augmented group might negate biological necessity of the bone substitutes for healing enhancement in DRF.
Likewise, reviewed literature heralds minimal concerns about non-union of DRF. In a prospective case series of 60 patients of DRF (i.e., AO-types A3 and C3) managed with non-augmented volar locked plating i.e., without bone graft or substitutes; Garcés-Zarzalejo et al demonstrated healing of all included fractures without significant reduction loss; stating that bone grafts/substitutes were not mandatory in management of unstable DRF [6].
Technical considerations
Bone substitutes
In spite of controversial superiority of block form of the bone substitutes in preventing secondary displacement of DRF; granular form was of choice in the present study because of its easier application within the metaphyseal void.
Besides, impaction of the bone substitutes was performed via the dorsal approach because it enables the surgeon to directly tackle the void through the dorsal metaphyseal comminution (i.e., without creating a cortical window); and also, this approach facilitates direct visualization (when needed) of articular surface the distal radius through dorsal capsulotomy.
In the current study, average estimated cost of used bone substitutes was 48$ /case which might significantly add to the increasing economic burden of DRF management especially in the light of common incidence of DRF (i.e., the second most common elderly skeletal fracture; accounting for 18% of all skeletal fractures); and in addition, current tendency of longer life expectancy and relatively higher level of activity among aging population than in past decades [15,16,17].
Method of fixation
In the present study, percutaneous pinning was selected over other methods of fixation (e.g., volar plating and external fixator) because of patient related-factors (e.g., elderly age group with relatively higher prevalence of co-morbidities necessitating short operative time; and with relatively lower functional demands), significantly lower cost, minimally-invasive approach, and no need for reoperation for hardware removal [8, 18, 19]. In a cost-effective study, Franer et al reported that compared with percutaneous pinning; volar plating had significantly higher charges, payments and complication rate (e.g. median nerve irritation/entrapment and tendon rupture) [8].
Another factor was comparable reported functional and radiographic outcomes of commonly-used methods of fixation [2, 3, 7, 9, 18, 20]. In a randomized controlled study of 461 patients of DRF managed in 18 different trauma centers across United Kingdom, Costa et al reported no differences in functional outcomes of volar locked plating versus K-wire fixation; however, the later was cheaper and quicker to perform [2]. In a meta-analysis of 7 randomized controlled studies of 875 DRF, Chaudhry et al concluded that volar plating showed marginal superiority over percutaneous pinning in terms of ROM and functional scores mainly at early (i.e., 3-month) postoperative follow-up; however, radiographic parameters were statistically comparable at both 3- and 12-month postoperative evaluation [7]. Zong et al stated similar conclusion in an independent meta-analysis [20]. In a systematic review of 14 studies (10 of which were prospective randomized controlled trials) including 1306 patients of DRF, Franceschi et al demonstrated that both percutaneous pinning and volar locked plating achieved satisfactory functional and radiographic outcomes; and moreover, there was no clear superiority of either of the examined fixation methods [9].
Ulnar styloid
A point worth mentioning is that in the current study; no operative intervention was dedicated to associated fracture of the ulnar styloid as these fractures frequently heal and non-united fractures of the ulnar styloid are usually asymptomatic [21]. In addition, patients with concurrent IRUJ instability following DRF fixation were initially excluded in order to augment internal validity of the current study.
Arthroscopic approach
Otherwise, recent techniques of arthroscopic-assisted reduction and osteosynthesis of displaced intra-articular DRF are currently scrutinized. Rationales behind these techniques included persistence of intra-articular step-off (in 22% out of 249 DRF) even if reduction seemed to be achieved under fluoroscopy; exclusion of intra-articular screw penetration, associated carpal stability and concurrent injury of triangular fibro-cartilage complex; and furthermore, satisfactory functional and radiographic postoperative outcomes [22, 23].
Actually, in spite of well-developed wrist arthroscopic practice in the institution; arthroscopic-assisted reduction/fixation of DRF was not exercised in the current study due to factors related to insurance coverage, emergency operative theatre time management, patients’ co-morbidities, and expected high cost-effective ratio of the technique. The later drawback can be attributed to disadvantage of (1)-troublesome technical setup (e.g., alternating vertical traction application/release and maneuvering of imaging intensifier); and (2)-arthroscopy-related complications (e.g., fluid extravasation and neurological injury); both disadvantages surpass expected advantages of arthroscopic-assisted reduction/fixation.
Complications
From another perspective, pin tract infection was diagnosed in 7 (36.8%) and 8 (38.1%) patients in the augmented and non-augmented groups respectively. Such infection was successfully managed by dressing and oral antibiotics except in 4 patients (i.e., 1 and 3 patients in the augmented and non-augmented groups respectively) in whom infection was further complicated by pin loosening necessitating earlier pin removal by an average of 4.7 postoperative weeks.
It goes without saying that precautions guarding against CRPS were strictly followed throughout the study; nevertheless, CRPS was early diagnosed in 7 patients; i.e., 3 (15.8%) and 4 (19%) patients in the augmented and non-augmented groups respectively. By final follow-up, this major complication has resolved aided by analgesics, anti-edematous medication, neurotonics, and aggressive ROM exercise.
No other major complications of neuro-vascular compromise, intra-articular escape of bone substitutes, wound and/or deep infection or tendon rupture could be reported.
Consistency of the study
In this study, certain factors were considered to ensure consistency of study outcomes as; (1) prospective cohort study design; (2) strict adherence to inclusion and exclusion criteria to avoid bias related to inclusion of different fracture patterns or associated ipsilateral fractures; (3) matched studied groups; (4) standardized operative technique notably with regard to surgical approach, method/configuration of fixation and bone substitutes (i.e., all cases were performed by or under supervision of the author); (4) strict commitment to a standardized postoperative rehabilitation protocol; and finally, (5) use of postoperative secondary displacement of the radiographic parameters as an outcome for assessment of postoperative stability of the fixation construct.
It is essential to point out that assessment of radiographic parameters was carried out 6 weeks following K-wire removal (i.e., at a total of 12 postoperative weeks) to take into consideration possible post-removal secondary fracture displacement according to some reports and to ensure solid fracture healing prior to radiographic evaluation [2, 3, 9].
Limitations
Undoubtedly, currently-reported study had its own limitations which included elderly patient groups (i.e., groups of low energy trauma and of relatively lower functional demands); small number of patients; exclusion of patients with concurrent IRUJ instability; use of granular form of bone substitutes (i.e., not solid blocks); technical variability in plain X-ray imaging protocol; and non-blinded assessment of outcome measurements.
In addition, radiographic outcomes were assessed by X-ray imaging solely without further CT evaluation. This is explained by widespread availability of X-ray imaging in common practice; and by radiation hazards and cost of CT imaging.
Moreover, duration of postoperative follow-up was relatively short; however, it was enough for assessment of primary outcome of the study (i.e., secondary displacement). On the other hand; incidence of post-traumatic osteoarthritis can’t be reported so that longer-term (e.g., 2-year) postoperative follow up studies are recommended.
Another limitation which might overshadow study outcomes is that it was carried out at a tertiary-level referral trauma center where surgeons are well-experienced in management of DRF.