Radiological Criteria for Instability in Distal Radius Fractures

1. Background Distal radius fracture is the most common fractures in adults, and there is agreement that there is a correlation between anatomical reduction and function in younger age groups (McQueen 1988, Cooney 1989). In the case of elderly patients (over 65 years), this is more debated (Egol 2010, Hassellund 2021, Panigrahi 2022). Dislocated distal radius fractures are initially treated with closed reduction and plaster (Arora 2011, Earnshaw 2002, Mackenney 2006). An unstable distal radius fracture is a fracture that dislocates after casting despite a successful reduction (Chung 2023). It is important to find out as early as possible whether a fracture is unstable only with a cast, so that these patients can be operated on without unnecessary delay, as a delayed operation can lead to reduced function (Selles 2021). Many have tried to come up with criteria that can predict whether the fracture is too unstable for plaster treatment only, but currently there are no standard criteria for this (Mackenney 2006, Lafontaine 1989, Nesbitt 2004, Abbaszadegan 1989, Tahririan 2013, Hove 1994, Leone 2004 ). Only increasing age, female gender and dorsal cortical comminution (all of which are factors that can indicate osteoporosis/osteopenia) have been shown to be significant criteria based on a meta-analysis from 2016 (Walenkamp 2016). However, there is a need for further studies of this, as practice now differs between the various hospitals in Norway, and also between different countries. According to the Norwegian guidelines, a distal radius fracture is considered for surgery based on certain radiological criteria. For patients under 65 years of age, it is strongly recommended to operate on a distal radius fracture if there is ≥ 10 degrees of dorsal angulation of the radius articular surface (from 90º on the longitudinal axis of the radius), ulnar variance ≥ 2 mm, intra-articular step ≥ 2 mm, incongruence in the distal radioulnar joint or cortical comminution in the fracture area/substance loss of the dorsal cortex of the distal radius before reduction. If one chooses conservative treatment for a well-reduced but possibly unstable fracture, it is good practice to follow the patient with regular X-ray checks. In American guidelines, there is a moderate recommendation to operate on fractures with dorsal tilt more than10 degrees, ulnar variance more than 3mm, intra-articular diastasis or step more than 2 mm after reduction. The recommendations behind the guidelines in Norway and in the USA are based on various studies with varying degrees of strength, as well as the surgeons experiences. Most of these studies include patients over 65 years of age, and increasing age has been shown to be one of the strongest indicators of whether a reduced fracture dislocates (Mackenney 2006). Many studies also exclude patients who have been set up directly for surgery without the criteria for why these patients have been considered for surgery being specified in more detail (Walenkamp 2016). Furthermore, most studies do not distinguish between displaced and minimally displaced fractures. Dorsal angulation that is accepted varies from 10-15 degrees from the neutral plane or 5 degrees from the starting point in various studies. Dorsal cortical comminution is not defined in most studies. Intra-articular fractures are often also included without any reflection on this. Some studies show that these are more unstable than extra-articular fractures (Lutz 2011). Although the meta-analysis (Walenkamp) from 2016 did not find that intra-articular fractures are more unstable, it was discussed whether part of the reason could be that many intra-articular fractures go straight to surgery and that only the least dislocated intra-articular fractures are considered for conservative treatment.
2. Problems and goal setting There is reason to ask whether the guidelines, especially the Norwegian ones, can lead to overtreatment, as clinical experience indicates that a portion of the distal radius fractures in patients between 18 and 65 years of age retain their position after closed reduction without surgery. In particular, this applies to extra-articular A fractures (based on the AO classification), as it has been shown that dorsal tilt is what most often triggers an indication for surgery (Cross 2022). Most people would agree that there is a difference between a comminuted, intra-articular fracture that is reduced to a suboptimal position, and a simple A2 fracture with a dorsal angulation of 20 degrees that is reduced to an anatomical position, but often this last group still ends up with surgery . There are no guidelines that separate these types of fractures. The question is how we can select the fractures that maintain their position after closed reduction. A closed reduction is considered successful when the most anatomical appearance of the bone is achieved. Whether the volar cortex is hooked on after reduction has been shown to be an important indication that a fracture holds its position (LaMartina 2015, Phillips 2014), but none of the guidelines in Norway, the USA, Great Britain or Denmark include this as a criterion. Only the Swedish guidelines have taken this into consideration. In addition, it should be considered whether patients between 50-65 years should be separated as a group, as many of these patients have osteoporosis/osteopenia. The following study is planned as part of the doctoral work of Ingrid Oftebro: Which radiological criteria can predict that the position of a distal radius fracture remains stable in the cast after closed reduction? Main quiestion: Can we find out which of the distal radius fractures maintain their position after closed reduction in patients between 18 and 65 years of age (with focus on volar hook and dorsal comminution)? It is important to find out whether some patients are unnecessary operated based on Norwegian and international guidelines. Needless operations can cause complications and stress for the patient that could have been avoided (Cross 2022, Rozental 2003). From a socio-economic perspective, it is also important to avoid unnecessary operations. Which radiological criteria before and after closed reduction of a distal radius fracture can help us to best predict whether a fracture retains its position in the cast?
3. Method The study is planned as a prospective study where consent will be obtained from the patient to look at various radiological criteria before and after reduction. Patients who are included must be between 18 and 65 years of age and have a dorsally displaced distal radius fracture that is reduced to an acceptable position (VLDV 75-95, RIV more than 15 degrees, ulnar variance less than 2 mm, step in the articular surface less than 2 mm) . Patients between 50-65 are more susceptible to osteoporosis/osteopenia, and we want to separate these as a group. All patients with low-energy fractures over the age of 50 are offered an osteoporosis examination at the OUS, and we can thus record the proportion of patients in this group who are diagnosed with osteoporosis/osteopenia. The patients will undergo normal closed repositioning with the traction method performed by LIS2 doctors/senior doctors and a plaster-technician/nurse. X-ray is taken before reduction, and X-ray and CT after reduction. X-ray will also be taken of the healthy side to be able to measure shortening more accurately, as there are anatomical variants. A common x-ray of the wrist consists of a PA projection (frontal projection) and a lateral projection with 15 degrees angulation (Medoff 2005). We will include extra-articular fractures (A2/3-fractures) and intra-articular fractures (C1/2-fractures) with intraarticulare step less than 2 mm before reduction. We want to examine the following radiological criteria (before and after repositioning): dorsal dislocation, ulnar variance, whether the volar cortex is hooked, to what extent there is a radial displacement/ad latus, radial inclination (RIV), radial height, dorsal, radial and ulnar comminution, carpal alignment and accompanying fracture of the ulna styloid process (avulsion fracture or at the base). In addition, we want to look at the extent to which the degree of dislocation before repositioning will affect whether the positions are maintained after repositioning. If a patient agrees to join the study, he or she will have a follow-up 6-8 days after reduction, where we will check if the fracture holds its position. If there is redislocation of the fracture beyond the limits mentioned above, the patient will be set up for surgery. X-rays before and X-rays and CT after reduction, as well as at follow-ups, will be examined with regard to the criteria mentioned above. Two experienced senior doctors at the out-patient clinic and a doctor specialising in orthopedic hand surgery at the orthopedic department OUS, Ullevål, will evaluate the X-rays, and where the measurements are not the same, the group will sit down to reach an agreement on the measurements. If the fracture has kept its position, they will be checked after another 6-8 days to check for late dislocation. If there is a slight redislocation within the above mentioned limits, a third follow-up will be scheduled within 3 weeks from injury. X-rays when the cast is removed (after 5 weeks) will also be examined in the patients where the fracture has maintained its position at the controls. The patients will take a final X-ray after 3 months. Complications such as CRPS (complex regional pain syndrome), osteotomy in the course due to symptomatic malunion, etc. will be recorded. We plan to include patients in a 2-year period from 01/10/2024 to 31/09/2026 at the outpatient clinic at the orthopedic department, OUS Ullevål (assumed N = 212). An experienced statistician from the University of Oslo will help with the calculations.
4. The importance of the project

The project will provide new knowledge about distal radius fractures in patients between 18 and 65 years of age and about the need for operative treatment after attempts at conservative treatment with closed reduction and casting. This knowledge will help to give the individual patient the best possible treatment so that unnecessary waiting for surgery and unnecessary operations are avoided. It will provide the opportunity to include new/more complementary criteria to the national guidelines in order to obtain better clinical assessment, and to avoid overtreatment. This will be important for the patients (avoid complications/burden by operating), as well as a socio-economic significance as surgery can lead to increased costs compared to conservative treatment with plaster. Distal radius fracture is the most frequently operated fracture in orthopedics, and there is therefore a large volume that can potentially be reduced.