Abstract
Background Due to the commonality of distal radius fractures (DRFs), the potential impact of ulnocarpal abutment (UA) on patient outcomes is significant, whether it developed after or prior to injury. It is, therefore, important to consider whether preexisting UA has any impact on outcomes after an acute DRF.
Questions/Purpose The aims of this study were to determine if differences were present in (1) pain at final follow-up, (2) complications, and (3) unintended operations in patients with DRFs and either without or with preexisting radiographic UA.
Methods A single institution retrospective cohort study comparing patients treated either nonoperatively (43 patients) or operatively (473 patients) for DRFs between 5/1/2008 to 5/1/2018 was performed. Data included demographics, prior wrist pain or surgery, ulnar variance, select treatment data, and presence of pain, complication, or unintended operation by final follow-up. Statistical testing used Fisher's exact test and chi-squared test, with a significance level of 0.05.
Results The prevalence of preexisting UA was 14.0 and 15.6% in the nonoperatively- and operatively treated groups, respectively. In nonoperatively treated patients without or with UA, no differences in pain (37.8 vs. 33.3%, p = 1.00) or complications were seen (13.5 vs. 50.0%, p = 0.07). A higher unintended operation rate for nonoperatively treated DRFs with UA, compared with those without, UA was seen (5.4 vs. 50.0%, p = 0.01). No differences in pain, complications, or unintended operations were seen between those without and with UA in the operatively treated group.
Conclusion Preexisting UA is not associated with pain, complications, or unintended operations after operative treatment of DRFs. Prospective studies further evaluating outcomes in nonoperatively treated DRFs with UA may be beneficial.
Keywords: distal radius fracture, lunate, open reduction and internal fixation, ulna, ulnocarpal abutment
Ulnocarpal abutment (UA), leading to impaction of the distal ulna against the proximal lunate, 1 can lead to ulnar-sided wrist pain manifesting as ulnar impaction syndrome (also referred to as UA syndrome). 2 Radiographs of the affected wrist frequently demonstrate ulnar positive variance, 3 but may have ulnar neutral or ulnar negative variance 4 with dynamic ulnar lengthening seen in a pronated grip radiograph. 1 5 Although UA can have an idiopathic etiology, 6 7 other potential causes include Madelung's deformity, 8 prior forearm trauma due to Essex-Lopresti injury, 9 and malunion following a distal radius fracture (DRF). 10 11 12 Posttraumatic UA following DRFs has been extensively studied for both nonoperatively 11 13 or operatively 14 15 treated DRFs. Chronic ulnar-sided wrist pain several months after the DRF 14 can develop and is a common reason for subsequent treatment with ulnar shortening osteotomy 12 15 or simultaneous radial closing wedge and ulnar shortening osteotomies. 11 Isolated ulnar-shortening osteotomy (USO) in the Tatebe et al study 12 demonstrated increases in grip strength and wrist flexion/extension arc in 16 patients with malunited DRFs and Wada et al 11 showed improvements in pain, function, and wrist range of motion in the 5 patients of their series. Due to the commonality of DRFs (640,000 cases in the United States annually), 16 the potential impact of UA on patient outcomes is significant, whether it developed after or prior to injury. It is, therefore, important to consider whether preexisting UA has any impact on outcomes after an acute DRF, which has not been well-described in the literature (to our knowledge).
In this manuscript, we describe a retrospective cohort study comparing patients with DRFs and either with or without preexisting radiographic UA. Our primary null hypothesis of interest was that there was no difference in postoperative complication rates between patients with DRFs and radiographic UA and patients with DRFs and without radiographic UA. Secondary null hypotheses of interest in this study explored if no differences existed in (1) pain rates at final follow-up visits and (2) unintended operation rates in patients with DRFs and either with or without preexisting radiographic UA. We also summarized data regarding demographics, treatment outcomes, radiographic findings, and the prevalence of preexisting radiographic UA in these two DRF treatment groups.
Methods
Study Population
After obtaining Institution Review Board approval for this investigation, we performed a retrospective cohort study of patients treated by eight hand surgeons in a level 1 trauma tertiary care medical center. This investigation was performed by using the inclusion criteria of (1) all patients having Common Procedure Terminology (CPT) codes 25607, 25608, and 25609 associated with open reduction and internal fixation (ORIF) of a DRF, (2) all patients with International Classification of Diseases-9 and -10 codes 813.40–44, 813.50–54, 813.80–83, 813.90–93, and S52.501-S2.599 corresponding with a diagnosis of a DRF, (3) initial evaluation in our institution's hand and upper extremity center between 05/01/2008 and 05/01/2018, (4) minimum of 3 months (12 weeks) of follow-up following initial evaluation, and (5) anteroposterior and lateral radiographs of the affected wrist at initial evaluation and final follow-up. Patients with inadequate follow-up duration or radiographs were excluded. The study population did include patients with a DRF as a solitary injury as well as those with other injuries (i.e., patients who presented to our institution as a trauma activation). After applying these 5 inclusion criteria, the initial number of operatively treated DRF cases was reduced from 1,132 to 473 candidate cases. Similarly, application of the 5 inclusion criteria reduced the initial number of 1,579 nonoperatively treated DRF cases to 43 cases. Thus, a total of 516 patient cases were included for further data collection and analysis.
Data Collection
From electronic medical record review, demographics, handedness, injury laterality, prior injuries, surgery, and pain in the affected wrist were noted. Time to treatment was also calculated, defined as days from injury to either the start of nonoperative treatment or surgery. In addition, length of follow-up, complications, reoperations (both total reoperations rate and reoperations due to ulnar pathology), and presence of pain at follow-up visit were recorded as the outcome variables of interest. Complications were defined as any unexpected outcome during the course of treatment of the DRF (e.g., infection, reoperation, and hardware failure). The determination of the presence of pain or a complication was done via documentation by the patient's treating surgeon. The type of treatment rendered (nonoperative or operative) was also recorded. Review of radiographs was performed by two of the authors, a resident physician and a fellowship-trained hand surgeon, to determine the presence of sclerosis or cysts in the proximal ulnar quadrant of the lunate at time of injury (as an indicator for the presence of preexisting radiographic UA). Therefore, preexisting UA in this investigation was defined solely by the aforementioned radiographic findings. Patients with both preinjury wrist pain and radiographic findings of preexisting UA would be termed as having “symptomatic preexisting UA.” In contrast patients, without preinjury wrist pain but with preexisting radiographic UA would be considered to have “asymptomatic preexisting UA.” These two authors also standardized measurement and recording of radiographic parameters such as ulnar variance (in millimeters) after closed reduction had been performed. The wrist radiographs used in our evaluation were obtained with standard neutral rotation views by one of two trained radiology technicians in our institution's hand clinic. Finally, the progression of lunate sclerosis or cysts at the time of final radiographs was recorded. Fig. 1 illustrates an example of preexisting radiographic UA at the time of DRF, which persisted after ORIF.
Fig. 1.
Example anteroposterior and lateral radiographs in a 53-year-old female patient who sustained a closed right distal radius fracture (DRF) and had cystic changes in the proximal ulnar corner of the lunate consistent with preexisting radiographic ulnocarpal abutment. Specific images shown include ( A ) initial radiographs at the time the DRF was sustained, ( B ) postreduction radiographs obtained in clinic used for final determination of nonoperative versus operative treatment of the DRF (with some dorsal redisplacement of the DRF), and ( C ) postoperative radiographs obtained 6 months after open reduction and internal fixation of the DRF. In the final set of radiographs, cystic changes in the lunate are still present.
Statistical Analysis
Normally distributed data (such as age) were described with mean ± standard deviation and non-normal data (such as ulnar variance) were described with median and interquartile range (IQR), after evaluation of normality with the Shapiro–Wilk test. Categorical variables were described with counts and proportions. Statistical testing of the null hypotheses of interest was accomplished with the Fisher's exact test for the nonoperatively treated DRFs and the chi-squared test for operatively treated DRFs. An a priori power analysis was performed, with a doubling of the 22% complication rate following volar plate fixation of DRFs found by Lutz et al. 17 defined to be the minimum clinically important difference (MCID). This was selected by the authors, since no established MCID exists for complication rates after treatment of DRFs. This led to a sample of 90 operatively treated DRFs without UA and 70 operatively treated DRFs with UA (160 total cases) yielding a power of 80% to detect the MCID with an α = 0.05. Results of statistical testing were reported as p values. All statistical analyses utilized a standard commercially available software program.
Results
Demographics and Other Pretreatment Characteristics
The prevalence of preexisting radiographic UA was 14.0% in nonoperatively treated patients and 15.6% in operatively treated patients. Patients with UA tended to be older than those without UA in both the nonoperative (69.5 ± 11.6 years vs. 57.9 ± 17.9 years) and operative (61.4 ± 13.2 years vs. 55.0 ± 16.8 years) treatment groups ( Table 1 ). The sex ratios were similar in those without and with UA in the nonoperative (81.1% female vs. 50.0% female) and operative (63.2% female and 68.9% female) groups, given the small patient numbers in the nonoperatively treated group. Moreover, the proportions of those with prior pain, injuries, or operations to the wrist affected by the DRF were similar between patients with and without UA, for both the nonoperatively- and operatively treated groups ( Table 1 ). A trend toward more positive ulnar variance was seen in those with UA compared with those without UA in the nonoperative (median of –1.3 mm [IQR: –2.7–1.4] vs. median of –0.4 mm [IQR: –1.2–0.5]) and operative (median of 1.9 mm [IQR: 0.2–4.2] vs. median of 1.1 mm [IQR: –0.7–3.5]) groups.
Table 1. Demographics and other select pretreatment characteristics of patients with distal radius fractures.
| Nonoperatively treated patients ( N T = 43 patients) | Operatively treated patients ( N T = 473 patients) | |||
|---|---|---|---|---|
| Variable | Without preexisting UA ( N 1 = 37 patients) | With preexisting UA ( N 2 = 6 patients) | Without preexisting UA ( N 1 = 399 patients) | With preexisting UA ( N 2 = 74 patients) |
| Age (y) | 57.9 ± 17.9 | 69.5 ± 11.6 | 55.0 ± 16.8 | 61.4 ± 13.2 |
| Sex (number of females) | 30 (81.1%) | 3 (50.0%) | 252 (63.2%) | 51 (68.9%) |
| Handedness (number right-handed) | 27 (90.0%) | 5 (83.3%) | 297 (91.1%) | 62 (95.4%) |
| Injury laterality (number on right side) | 13 (35.1%) | 1 (16.7%) | 201 (50.4%) | 28 (37.8%) |
| Prior Injuries to affected wrist (number with prior injury) | 0 (0%) | 0 (0%) | 13 (3.3%) | 1 (1.4%) |
| Prior surgeries to affected wrist (number with prior surgery) | 1 (2.7%) | 0 (0%) | 15 (3.8%) | 2 (2.7%) |
| Pain in affected wrist prior to injury (number with prior pain) | 0 (0%) | 1 (16.7%) | 5 (1.3%) | 1 (1.4%) |
| Ulnar variance at initial evaluation (millimeters) | −0.4 (−1.2–0.5) | −1.3 (−2.7–1.4) | 1.1 (−0.7–3.5) | 1.9 (0.2–4.2) |
Note: Summary of demographic data and select pretreatment characteristics provided to nonoperatively- and operatively treated patients. Nonoperatively treated patients are further divided into those without preexisting ulnocarpal abutment (UA) (37 patients) and with preexisting UA (6 patients) in postreduction radiographs of the affected wrist, during initial evaluation. Similarly, operatively treated patients are divided into groups without UA (399 patients) and with UA (74 patients). Mean and standard deviation are given for normal variables, median and interquartile range (IQR) for non-normal variables, and number and proportion for categorical variables.
Treatment Characteristics and Outcomes
The time to treatment for nonoperatively treated patients was similar between those without and with UA (median of 5 days [IQR: 3–7 days] vs. median of 1 day [IQR: 1–7 days]) and a similar trend was seen in operatively treated patients ( Table 2 ). The durations of immobilization were similar in those without and with UA in the nonoperative (62 ± 29 days vs. 64 ± 29 days) and operative (52 ± 34 days vs. 53 ± 25 days) groups. No UA-associated radiographic changes developed in nonoperatively- or operatively treated patients without preexisting UA. Of patients with preexisting UA, 3 (50%) nonoperatively treated patients and 50 (67.6%) operatively treated patients had progressive sclerotic or cystic changes of the lunate in final radiographs.
Table 2. Treatments and outcomes of patients with distal radius fractures.
| Nonoperatively treated patients ( N T = 43 patients) |
Operatively treated patients ( N T = 473 patients) |
|||
|---|---|---|---|---|
| Variable | Without preexisting UA ( N 1 = 37 patients) | With preexisting UA ( N 2 = 6 patients) |
Without preexisting UA ( N 1 = 399 patients) | With preexisting UA ( N 2 = 74 patients) |
| Time to treatment (days) |
5 (3–7) | 1 (1–7) | 7 (4–12) | 8 (5–16) |
| Duration of immobilization (days) |
62 ± 29 | 64 ± 29 | 52 ± 34 | 53 ± 25 |
| Length of follow-up (days) |
143 (99–174) | 211 (102–537) | 131 (98–198) | 119 (96–207) |
| Pain at final follow-up visit (number with pain) |
14 (37.8%) | 2 (33.3%) | 146 (36.6%) | 24 (32.4%) |
| Complications (number who developed a complication) |
5 (13.5%) | 3 (50.0%) | 122 (30.6%) | 18 (24.3%) |
| All unintended operations (number needing operation) |
2 (5.4%) | 3 (50.0%) | 79 (19.8%) | 11 (14.9%) |
| Unintended operations due to ulnar pathology (number needing operation) |
1 (2.7%) | 2 (33.3%) | 12 (3.0%) | 3 (4.1%) |
Abbreviation: UA, ulnocarpal abutment.
In nonoperatively treated patients without or with UA, no differences in pain (37.8% vs. 33.3%, p = 1.00) or complications (13.5% vs. 50.0%, p = 0.07) were seen ( Table 2 ). Three unintended operations occurred for nonoperatively treated DRFs with UA: one for open distal ulnar wafer excision, one for ipsilateral distal ulna nonunion, and one for extensor pollicis longus tendon rupture. Significant differences were seen for unintended operation rates in nonoperatively treated DRFs for all indications (5.4% vs. 50.0%, p = 0.01) and for ulnar pathology specifically (2.7% vs. 33.3%, p = 0.047).
Similarly, no differences in the proportions with affected wrist pain at final follow-up (36.6% vs. 32.4%, p = 0.49), complications (30.6% vs. 24.3%, p = 0.28), and unintended operations for all indications (19.8% vs. 14.9%, p = 0.32) were seen in patients with and without UA who were operatively treated ( Table 2 ). Unintended operations for ulnar pathology did trend higher for those operatively treated patients with UA, but this difference was also not significant (3.0% vs. 4.1%, p = 0.72).
Discussion
For clinically symptomatic UA, several surgical treatment options (e.g., intraarticular and extraarticular osteotomies) currently exist. 18 However, it remains unknown if surgical treatment of preexisting radiographic UA, especially if it was previously asymptomatic, is advised during the treatment of DRFs (especially those DRFs that are operatively treated). It is well-known that DRFs, regardless of the treatment option, are predisposed to subsequent UA if they heal in a malunited position with shortening of the distal radius. 19 20 Given that outcomes of DRFs with preexisting UA have not, to our knowledge, been previously explored in the literature, we sought to compare outcomes in patients with DRFs and preexisting radiographic UA and compare them to patients with DRFs and no radiographic UA.
In regard to our study hypotheses, we were unable to reject the null hypotheses that there is a difference in wrist pain at final follow-up or complication rates during treatment between patients with DRFs and UA and those with DRFs and without UA (for both nonoperatively and operatively treated patients). Furthermore, we found that there is no difference in unintended operation rates between DRF patients with and without UA (when DRFs were operatively treated). Complications during nonoperative treatment, especially within several weeks of injury, were likely attributable to the DRF itself and not the more chronic process of UA. In regard to no differences in pain at final follow-up, similar numbers of patients had preexisting pain in all four study subgroups and after resolution of their DRF likely reverted back to baseline pain levels. We did also find that (a) 1 of the 6 patients with a nonoperatively treated DRF and preexisting radiographic UA and (b) 1 of the 74 patients with an operatively treated DRF and preexisting radiographic UA had “symptomatic preexisting UA.” One of the unintended operations in the nonoperatively treated DRF group was directly attributable to UA syndrome, one was also associated with ulnar-based pathology, and one likely occurred independently from the presence of ulnar-based pathology.
Our study design demonstrates several important strengths. First, the sample used (516 patients identified in the 10 years time period of the study that met inclusion criteria) was comparable to other outcome studies of DRFs in a single-institution. 15 21 In addition, we utilized the presence of lunate cysts as an indicator for radiographic UA, which has a sixfold higher incidence in patients with symptomatic UA syndrome versus those patients without ulnar-sided wrist pain. 22 23 Furthermore, changes in lunate cyst size have been seen after treatment of UA syndrome with USO 23 and thus progression of cystic changes in our cohort can offer useful information on the contribution of DRF to worsening UA. Other researchers have noted progressive degenerative changes in the natural history of UA. 24 25 In light of our findings of progression of UA after DRFs, further long-term follow-up studies may be warranted. Finally, we determined the prevalence of preexisting UA in patients with DRFs and assessed the potential impact of UA on nonoperative and operative treatments of DRFs, which have not been described previously in the literature (to our knowledge).
In addition to the several aforementioned strengths, our investigation did have notable limitations. For example, no standardized preoperative and postoperative assessments of pain, such as the Visual Analog Scale (VAS), or function, such as the Disabilities of the Arm, Shoulder, and Hand (DASH) or wrist grip strength testing with a dynamometer were available. This limits the ability to discern preoperative and postoperative differences in pain levels (as opposed to simply the presence or absence of pain) and functional ability between patients without and with UA. Another limitation was absent preinjury wrist radiographs in patients with DRFs, thus limiting our ability to accurately discern other potential indicators of preinjury UA such as positive ulnar variance. We attempted to mitigate this by using postreduction radiographs of the wrist without obvious shortening of the distal radius, obtained during initial in-clinic evaluation, when definitive treatment was determined (nonoperative or operative). It is possible that other variables may explain the increased unintended operation rate in patients with nonoperatively treated DRFs with UA and must be evaluated with caution due to the statistical fragility in the comparison of this outcome. The minimum length of follow-up requirement should also be kept in mind, since it is likely that operatively-treated patients would have been more likely to follow up for that time period than nonoperatively treated patients. This 3-month minimum time interval may have been insufficient to assess for late complications (e.g., greater than 1 year after injury). On the other hand, this requirement for minimum follow-up length and the other inclusion criteria reduced the number of available operatively treated DRF cases by 58.2% and nonoperatively treated DRF cases by 97.3%. As a result, the large discrepancy in sizes between the operatively- and nonoperatively treated groups could be considered another limitation of this study, which may be addressed by requiring longer follow-up in potential future prospective studies for nonoperatively treated patients with DRFs. Of note, patients were usually followed by their treating surgeon until union occurred without active issues (e.g., infection), which is when most complications of interest would have occurred.
This study represents the first report of outcomes in patients with DRFs and either without or with preexisting radiographic UA. The prevalence of preexisting radiographic UA in patients treated nonoperatively and operatively for DRFs was similar (14% and 16%, respectively). In patients treated nonoperatively for DRFs, the presence of preexisting UA exhibited no difference in the outcomes of pain in the affected wrist at final follow-up or complications during the course of treatment. A significant increase in the unintended operation rate in nonoperatively treated patients with preexisting UA was seen but was statistically fragile. Similarly, no significant differences following operative treatment of DRFs were seen for pain at final follow-up, postoperative complications, and unintended operations between patients with and without preexisting UA. Thus, the overall lack of an effect of preexisting radiographic UA on patient outcomes argues against its utility in treatment decisions with regard to DRFs. However, this conclusion should be balanced against the fact that only the presence or absence of pain (a) prior to injury and (b) at final follow-up (binary outcomes) was used as the sole patient-based assessment of outcome as a function of (1) operative or nonoperative treatment and (2) presence or absence of radiographic preexisting UA. It would be informative to also ascertain if the degree of pain levels (e.g., with the VAS pain scale), location of pain (e.g., radial vs. ulnar), and function (e.g., with wrist grip strength testing and DASH surveys) differed between patients with and without UA. Future prospective investigations that included these pain and functional assessments may thus be able to comprehensively address the questions of (1) how many wrists with DRFs and asymptomatic UA develop symptomatic UA and (2) what is the degree of symptomatic impairment in subsequent symptomatic UA. In turn, answering these questions can add to knowledge gained from this investigation and address whether surgical treatment for UA should be done, particularly for patients with DRFs that would usually be managed nonoperatively. These future studies could also have larger numbers of nonoperatively treated patients, longer follow-up periods (e.g., 1 year or more), and more detail regarding patients' return to preoperative activities of daily living may be beneficial.
Funding Statement
Funding None.
Conflict of Interest None declared.
Ethical Approval
This study was approved by our Biomedical Institutional Review Board. Informed consent for this retrospective study was not required by our Biomedical Institutional Review Board. All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008. Informed consent was obtained from all patients for being included in the study.
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