➢ Distal radial fractures with >2 mm of articular incongruity are associated with worse functional outcomes.
➢ Anatomic reduction of acetabular fractures positively influences functional outcome and reduces the risk of posttraumatic osteoarthritis.
➢ Mild to moderate joint surface incongruity (≤4 mm) following tibial plateau fractures is well tolerated and generally is associated with good functional outcomes.
➢ Although anatomic reduction of tibial plafond fractures reduces the risk of radiographic arthrosis, it has yet to be proven to improve functional outcome.
Clinical Aspects of Intra-Articular Fractures
The current literature describes many factors that contribute to the outcome after an articular fracture. Many of these factors, such as social and environmental influences, medical comorbidities, secondary gain, and premorbid conditions, are beyond the surgeon’s control. Variables that the orthopaedic surgeon has at least modest influence on include the quality of reduction and rehabilitation1-4. It is vital that the surgeon maximize this influence through a better understanding of the importance of articular reduction and fixation after fractures.
A large body of basic science research supports the concept that malreduction leads to posttraumatic arthritis5-21. In addition, there is a growing understanding of how biological and genetic mechanisms come into play after articular trauma in the process of chondrocyte apoptosis, which results in cartilage degeneration22-28. With that being said, the present report is not meant to be a comprehensive review of articular injury but will focus clinically on the importance of articular fracture reduction on the basis of radiographic evidence and clinical outcomes.
For certain anatomic regions, such as the glenoid fossa, distal part of the femur, humeral head, femoral head, and talus, little to no information is available with regard to how much articular step-off or gap is acceptable. These injuries provide an opportunity to investigate the influence of reduction on outcomes.
We have further limited the scope of this review by not including fractures involving the sacroiliac joint or other pelvic ring injuries because these joints are not diarthrodial and have minimal motion. Likewise, midfoot, forefoot, carpal, and hand injuries are not covered as these distal lesions are often affected by instability patterns involving multiple joints and are without intra-articular step-off.
PubMed, Google Scholar, and select orthopaedic journals were searched for potentially relevant literature pertaining to the remaining articular fractures. Only human studies written in English were included. In addition, case reports and nonoperative studies were excluded. The remaining abstracts were reviewed to identify studies that included information on the effect of reduction on patient outcomes and posttraumatic arthritis.
Distal Humeral Fractures
Our review identified one study that correlated the quality of reduction with outcome following distal humeral fractures (Table I). Aslam and Willett29 followed twenty patients who had been managed with internal fixation. Postoperative radiographs were used to classify the fractures, according to the quality of reduction, as grade A (anatomic reduction), grade B (<2 mm of incongruity), or grade C (>2 mm of incongruity). Of the fourteen fractures with grade-A reduction, nine had an excellent outcome, three had a good outcome, and two had a fair outcome. Of the five fractures with a grade-B reduction, two had a good outcome and three had a fair outcome. The one fracture with a grade-C reduction had a poor functional outcome.
Radial Head Fractures
While there is insufficient research on the importance of reduction for radial head fractures, King et al.30 retrospectively examined the outcomes for fourteen patients who had been managed with open reduction and internal fixation for the treatment of Mason type-II and III fractures. Patients with Mason type-II fractures had an average Elbow Evaluation Score of 96.8 points (of 100)31. All type-II fractures were reduced to <2 mm of residual incongruity. Patients with Mason type-III fractures had an average functional score of 72.9 points, which was considered significantly different (worse) than that for patients with type-II fractures (p < 0.05). Interestingly, all of the type-III fractures were associated with residual incongruities of >2 mm, which the authors considered to be an indication of poor-quality reduction. In that study, the effect of anatomic reduction on elbow function may have been confounded by the severity of injury (Table I).
Distal Radial Fractures
The study by Knirk and Jupiter32 has guided the clinical treatment of fractures of the distal part of the radius for years. In that study, young adults ranging from nineteen to thirty-nine years of age were followed for a mean of 6.7 years after intra-articular fractures of the distal part of the radius. Twenty-two (92%) of twenty-four patients with any step-off and eight (100%) of eight patients with ≥2 mm step-off had radiographic osteoarthritis. Surprisingly, patients who had radiographic posttraumatic arthritis still reported good to fair wrist function. Recently, Haus and Jupiter33 reexamined the study by Knirk and Jupiter and concluded that it was flawed methodologically as accurate measurements of step incongruities could not have been made with use of anteroposterior radiographs; however, the authors thought that the original conclusions were still valid as multiple studies have demonstrated similar associations between residual displacement and arthritis34-36.
Catalano et al.34 reviewed the long-term results of distal radial fractures in young adults. Twenty-one patients who were managed with open reduction and internal fixation were evaluated subjectively, radiographically, and clinically (with regard to functional status) at a minimum of 5.5 years after the injury. Despite evidence of osteoarthritis in sixteen of the twenty-one patients, function was graded as good or excellent on the basis of the Musculoskeletal Function Assessment (MFA) questionnaire37. Consequently, wrist function was not correlated with the presence of arthritis. The authors found that arthritis was strongly correlated with the size of residual step and gap incongruities seen on radiographs. In a follow-up study, Goldfarb et al.35assessed sixteen of the twenty-one patients at a mean of fifteen years after treatment. The authors reported that the degree of radiographic arthritis had progressed; however, there was still no correlation between radiographic arthritis and function.
In 2007, Chung et al.36 prospectively evaluated several predictors of outcome after the operative treatment of distal radial fractures, including age, socioeconomic status, the severity of the fracture pattern, and postoperative radiographic measurements. Three months after the operation, the researchers reported that only less radiographic incongruity was a significant predictor of a good outcome (p = 0.04); however, at one year, only increased age and lower income levels correlated with lower Michigan Hand Outcomes Questionnaire (MHQ)38 scores.
Kreder et al.39 performed a randomized trial in which indirect reduction and percutaneous fixation was compared with open reduction and internal fixation for the treatment of displaced intra-articular fractures of the distal part of the radius and reported that patients with <2 mm of residual step or gap were less likely to develop posttraumatic arthritis as compared with those with greater amounts of residual displacement (Table II).
The landmark study by Letournel40 compared the results following the treatment of acetabular fractures with an anatomically ideal reduction with those following the treatment of fractures with an imperfect reduction and concluded that anatomic reduction is essential for a good prognosis. These findings have set operative guidelines for acetabular fractures for years, and numerous studies have confirmed the importance of anatomic reduction.
Residual displacement of 1 to 3 mm has been reported to negatively affect outcomes, to contribute to osteoarthritis, and to increase the likelihood of total hip conversion41-55. However, the type of radiographic study that is performed and the fracture location may influence what is considered acceptable. In most studies, residual displacement has been measured on postoperative radiographs, which have been shown to have relatively poor sensitivity for the detection of step and gap deformities56,57. Perhaps the true tolerance is greater than what has been reported on the basis of radiographic findings. Acceptable residual displacement also may depend on the location within the acetabulum. Studies have shown that fractures involving the weight-bearing dome may portend worse outcomes, whereas those with a residual gap or step outside this region can tolerate greater displacement50. Selected studies are reviewed in the following paragraphs, and all of the studies that we were able to find are summarized in Table III.
Matta41 retrospectively evaluated how the accuracy of reduction affects clinical results for all types of acetabular fractures. He followed patients for a mean of six years after open reduction and internal fixation. An anatomic reduction (defined as a reduction with ≤1 mm of incongruity) was achieved for 185 of the 262 acetabular fractures in the study. Statistical analysis revealed that congruent anatomic reduction correlated with an excellent or good clinical result according to the modified Merle d’Aubigné and Postel58 score (p = 0.002). This finding led Matta to conclude that in cases of complex acetabular fractures, posttraumatic arthritis can be avoided if the fracture is anatomically reduced.
Several studies have assessed the determinants of functional outcome following different types of acetabular fractures. Kreder et al.42 reviewed 128 posterior wall fractures at a minimum of one year after operative treatment. Patients with malreduced joints (>2 mm of incongruity) and those with marginal impaction exhibited a higher incidence of radiographic arthritis (p = 0.001 and p = 0.02, respectively).
Oh et al.43 retrospectively studied the outcomes following the operative treatment of transverse acetabular fractures. The latest results, at a mean of forty-three months, showed better clinical function (according to the modified Merle d’Aubigné and Postel score58) for patients with complete versus incomplete reduction. These scores were determined to be significantly different (p = 0.001).
Bhandari et al.44, in a study of patients with fractures of the acetabulum with concomitant posterior dislocation of the hip, evaluated several predictors of outcome, including the quality of reduction, the age of patient, associated injuries, damage to the femoral head, acetabular impaction, the type of fracture, and the time to relocation. Only the quality of reduction was found to be a good predictor of clinical function, radiographic grade, and the incidence of posttraumatic osteoarthritis (p < 0.001). All thirteen patients with residual acetabular articular incongruity developed osteoarthritis within eight years, compared with ten (10%) of the ninety-six patients with anatomically reduced fractures.
Murphy et al.45 also studied the effect of several prognostic factors on outcome following acetabular fractures, including sex, age, fracture type, the quality of reduction, hip dislocation, sciatic nerve palsy, and the interval between the injury and surgery. Regression analysis showed that imperfect reduction (>3 mm of incongruity) was prognostic of a poor result (p = 0.002). The authors also found that advanced age (p = 0.003) and worse fracture type (p < 0.001) were correlated with a worse quality of reduction.
Tannast et al.46 reviewed the records for 816 patients who were managed operatively by a single surgeon over a twenty-six-year period to determine factors that predict hip survival. The authors found that the rate of hip survival twenty years following operation was 79% (644 of 816). In the course of the study, they identified three negative predictors of survival that were related to operative intervention: a non-anatomic reduction, postoperative incongruence of the acetabular roof, and use of the extended iliofemoral approach.
Zha et al.47 retrospectively reviewed the records for eighty-six patients with an age of sixty years or more who underwent open reduction and internal fixation for the treatment of displaced acetabular fractures. Patients were followed for an average of thirty-nine months following surgery. The authors used a multivariate regression model to identify determinants of poor functional outcome based on the modified Merle d’Aubigné and Postel score58. They found that poor quality of reduction (t = −10.45, p < 0.000), comminuted posterior wall fracture (t = −2.74, p = 0.008), and femoral head injury (t = −3.51, p = 0.000) were correlated with a poor outcome. (In comparisons of two parameters, a t value further from 0 indicates a bigger effect on the outcome.)
Finally, in a prospective cohort study involving 129 patients who had had operative treatment of acetabular fractures, Borg et al.48 sought to evaluate changes in the quality of life over time according to responses on the Short Form-36 (SF-36) questionnaire. The authors found that respondents with an anatomic reduction scored better on the SF-36 (p = 0.001 to 0.039) in all of the quality-of-life measures except “vitality” (p = 0.07) when compared with patients with ≥2 mm of incongruity.
The current literature on the treatment of patellar fractures with articular surface incongruity recommends nonoperative treatment for fractures associated with ≤4 mm of step-off59,60. For patellar fractures with >4 mm of step-off, open reduction and internal fixation is the current treatment of choice. A search of the literature on the outcomes of operative fixation of patellar fractures according to the quality of reduction yielded few results.
Levack et al.60 retrospectively compared the functional outcomes following open reduction and internal fixation with those following patellectomy for the treatment of patellar fractures. The authors found that of the thirty patients in the internal fixation group, only 30% (nine) had a good result, 33% (ten) had a fair result, and 37% (eleven) had a poor result on the basis of pain, limitation of activity, loss of quadriceps power, and the patient’s subjective functional score. The authors commented that patients who had an anatomic reduction with internal fixation demonstrated better functional outcomes than those with a poor quality of reduction; however, they did not quantify the reduction quality.
Tibial Plateau Fractures
Previous research has shown good clinical results following tibial plateau fractures despite non-anatomic reduction. Weigel and Marsh61 demonstrated good knee function, based on Iowa Knee and SF-36 scores, at a minimum of five years following the treatment of high-energy tibial plateau fractures with external fixation even in the presence of a mean residual articular surface incongruity of 3.3 mm. They found that articular incongruity was weakly associated with radiographic evidence of arthrosis (r = 0.52, p = 0.011) but was not associated with functional measures.
A more recent case series by Manidakis et al.62 also demonstrated good clinical results despite residual joint surface incongruity at the tibial plateau. The authors noted that only seventy-one (56.8%) of the 125 patients had a good reduction (<2 mm) at the time of follow-up; however, eighty-six (69%) of the patients had a good clinical result according to the Knee Society Score at a mean of twenty months postoperatively.
In a five to twenty-seven-year follow-up study of patients with tibial plateau fractures, Rademakers et al.63 found no significant difference between fractures with <2 mm of residual step-off (101 patients) and those with 2 to 4 mm of residual step-off (eight patients) with regard to the prevalence of posttraumatic arthritis (p = 0.43).
In a retrospective study, Barei et al.64 investigated determinants of outcomes for patients with severe bicondylar fractures of the tibial plateau. Patients with AO/OTA Type-41-C3 bicondylar tibial plateau fractures were managed with medial and lateral plate fixation with use of a staged approach to operative intervention. The study showed that a good quality of reduction and less severe fracture type (≤2 mm of incongruity) correlated with better functional outcomes (p = 0.029 and p < 0.001, respectively) (Table IV).
Distal Tibial Fractures
Pilon fractures often portend devastating physical and economic results for those who sustain them65,66. Marsh et al.67 retrospectively reviewed the records for thirty-one patients who had sustained pilon fractures five to twelve years previously to determine what factors affect outcome. The authors graded quality of reduction radiographically on a scale of 1 to 10 and according to the Burwell and Charnley criteria68 as good, fair, or poor on the basis of the displacement of fracture fragments. The authors used the Spearman correlation coefficient, which tests the association between two ranked variables, and found that the arthrosis grade had a strong correlation with the reduction ranking (correlation coefficient = 0.65, p = 0.0002). A correlation coefficient of 1 indicates a perfect correlation. In addition, the Burwell and Charnley classification correlated with the Iowa Ankle Score, SF-36 physical function score, Ankle Osteoarthritis Scale disability score69, and arthrosis grade. Interestingly, the authors found that initial displacement and residual displacement correlated strongly with each other, which confounded residual displacement associations (Table V).
DeCoster et al.70 examined the outcomes following pilon fractures by creating a rank order method to compare the severity of the injury and the quality of the reduction. The authors used a series of twenty-five patients who were managed with articulated external fixation and limited internal fixation. The study failed to demonstrate any connection between the severity of injury, the quality of reduction, and the clinical ankle function score. The investigators determined that the quality of reduction correlated with radiographic evidence of arthrosis and accounted for 26% of the radiographic variability (p < 0.05).
In an additional effort to discover variables that influence the outcome following pilon fractures, Williams et al.71 used the rank order method developed by DeCoster et al. to stratify pilon fractures according to the severity of injury and the quality of reduction. They found that patient-specific socioeconomic factors more accurately predicted outcomes. Patients with higher education and income levels had higher ankle scores. In that study, the severity of injury and the quality of reduction again correlated with radiographic evidence of arthritis (p < 0.05) but not with the clinical ankle score.
Pollak et al.72 evaluated the outcomes for eighty patients at a mean of 3.2 years after a pilon fracture. They found that the general health of the patients was significantly poorer than age and sex-matched norms as reported with the SF-36 (p < 0.05). Of the sixty-five patients who had been employed prior to the injury, twenty-eight (43%) were not employed at the time of follow-up. Interestingly, patients who had been managed with external fixation with or without limited internal fixation demonstrated worse impairment in terms of range of motion than those who had been managed with open reduction and internal fixation (27% compared with 12%; p < 0.05), implying that poorer outcomes were associated with less-anatomic reductions. Patients who had undergone external fixation instead of open reduction and internal fixation also reported a pain score that was 25.1 points higher (worse) (p < 0.05). We believe that the worse functional outcomes reported for patients who had undergone external fixation as opposed to open reduction and internal fixation may be explained by the quality of reduction, although specific measurements were not recorded. An alternative explanation could relate to the greater number of open fractures and AO Type-C fractures in the external fixation group.
Sanders et al.73 evaluated the outcomes associated with 120 intra-articular calcaneal fractures after an average duration of follow-up of twenty-nine months (range, twelve to fifty-six months). The quality of the posterior facet reduction was determined on coronal computed tomography (CT) scans and was classified as anatomic, near anatomic (<3 mm of incongruity), approximate (3 to 5 mm of incongruity), or failure (>5 mm of incongruity). Outcomes were determined according to the Maryland Foot Score (MFS)73 and were stratified on the basis of the fracture classification. Anatomic reduction was attained for sixty-eight (86%) of the seventy-nine Type-II fractures, and a good or excellent outcome was achieved for fifty-eight (73%). Anatomic reduction was attained for eighteen (60%) of the thirty Type-III fractures, and a good or excellent outcome was achieved for twenty-one (70%). No anatomic reductions were achieved in the group of eleven Type-IV fractures, and the clinical results were uniformly poor. Although it is often stated that Sanders Type-IV fractures portend a poor prognosis because of the severity of injury, it is not possible to ascertain the relative contribution of poor reductions to these outcomes (Table VI).
Buckley et al.74 randomized patients to operative or nonoperative treatment, and the SF-36 scores were compared. Overall, there was no difference in scores between the groups. However, when the authors examined the operative treatment group, they found that patients in whom the fracture had been reduced anatomically (<2 mm) reported significantly higher SF-36 scores (p = 0.012).
Paley and Hall75 retrospectively investigated the outcomes for forty-four patients (fifty-two calcaneal fractures) who had been managed with open reduction and internal fixation. Functional outcome was scored on the basis of both subjective criteria (pain, activities of daily living, work, sports, difficulty walking, and the use of walking aids) and objective criteria (range of motion at the subtalar joint and the presence of a limp). The authors reviewed radiographs to determine subtalar joint congruity and found that twenty-five (48%) of the fifty-two fractures were associated with residual joint incongruence (>2 mm) after four to fourteen years of follow-up. Thirteen (52%) of twenty-five fractures in patients with incongruent joint surfaces had an unsatisfactory result, compared with seven (26%) of twenty-seven fractures in patients with congruent joint surfaces.
In 2011, Tomesen et al.76 retrospectively reviewed the records for thirty-nine patients with displaced intra-articular calcaneal fractures that were treated according to the method of Forgon and Zadravecz. Functional outcomes were measured with use of the American Orthopaedic Foot & Ankle Society (AOFAS)77 score and the MFS. Patients also completed the SF-36 questionnaire. The authors found that the overall quality of reduction (as determined by restoration of calcaneal length, height, and width) and fracture severity were not correlated with the functional outcome measures. However, the authors suggested that this finding may have been due to the limited power of the study.
There are several difficulties in the clinical application of the findings derived from studies assessing the correlation between outcomes and the quality of articular reduction. One problem is the accuracy of the method used to determine the quality of reduction. In one technique, the surgeon assesses reduction intraoperatively, which may or may not be accurate depending on the amount of fracture exposure. Additionally, during the time of healing, fragments may shift, rendering the initial valuation of reduction obsolete62. Another commonly used method is radiography, which is known to be relatively inaccurate for detecting articular step and gap deformities. In practice, radiography is being supplanted by CT for the evaluation of many fractures as it is more accurate for detecting incongruity. Borrelli et al.56, in a study of acetabular fractures with ≥2 mm of displacement, found that CT had a sensitivity of 100% for detecting step deformity and 89% for detecting gap deformity, whereas radiography had sensitivities of 33% and 89%, respectively.
A second difficulty in the clinical application of the findings of studies assessing the correlation between outcomes and the quality of articular reduction is that in many cases there is no correlation between radiographic evidence of osteoarthritis and functional impairment. While many of the studies reviewed showed that quality of reduction is correlated with radiographic evidence of osteoarthritis, it is not known when this finding becomes functionally relevant. This lack of correlation may be due to the small number of trial participants in most studies, inadequacy in the duration of follow-up, or the absence of any correlation between radiographic osteoarthritis and functional deterioration. This being said, further research is necessary to establish to what degree, if any, radiographic osteoarthritis correlates with a decline in joint function.
Finally, these studies did not account for potential confounders, such as social and environmental influences, medical comorbidities, secondary gain, and premorbid function. Ideally, these factors would be assessed and analysis would adjust for any confounders that were identified.
It is of the utmost importance to balance the goal of anatomic reduction with other principles of fracture management. A poor result and complications may be inevitable following severe injuries as well as in patients with impaired healing capabilities, and aggressive dissection to obtain anatomic reduction may do more harm than good. The following recommendations should be interpreted with this in mind.
There is a paucity of literature regarding the effect of articular reduction on outcomes following fractures of the glenoid fossa, humeral head, femoral head, and distal part of the femur. The reasons for the limited information include the fact that these fractures are rare and are reported only in small case series, which makes meaningful analysis impossible. In addition, certain articular fractures are often treated with arthroplasty because of the difficulty of obtaining an accurate reduction or the high rate of associated osteonecrosis. Therefore, no evidence-based recommendations can be made at this time with regard to the importance of reduction quality.
Similarly, in distal humeral fractures, anatomic reduction was shown to be important for a good functional result in a small set of patients29; however, there is not enough evidence to make a definitive conclusion. For the same reason, insufficient evidence exists to make a recommendation regarding the importance of reduction for radial head fractures.
We believe that there is sufficient evidence to suggest that an anatomic reduction contributes to a good functional outcome following distal radial fractures. While studies by Knirk and Jupiter32, Catalano et al.34, and Goldfarb et al.35 demonstrated nonfunctionally significant evidence of radiographic arthritis in malreduced joints, studies by Chung et al.36 and Bini et al.78 demonstrated that residual joint surface incongruities at the wrist resulted in worse functional outcomes. Despite differences in the findings of those studies, the evidence points to the importance of accurate reduction in at least preventing the radiographic changes of osteoarthritis and preventing or delaying a decline in wrist function.
Evidence from the available literature on acetabular fractures underscores the importance of an anatomic reduction. Those studies indicate that good clinical results can be achieved even in patients with complex acetabular fractures if the surgeon is able to achieve an anatomic reduction41,43-45,47,48,79. Also, the progression to osteoarthritis may be slowed or prevented by anatomically reducing acetabular fractures after injury41-44,46.
With regard to patellar fractures, Levack et al.60 reported worse outcomes following open reduction and internal fixation as compared with patellectomy; however, it is impossible to assess the degree to which anatomic reduction contributed to functional outcome because of the confounding factors of patellar displacement and extensor mechanism injury that were present. In order to fully appreciate the importance of anatomic reduction in patellar fractures, more studies need to be done to assess the correlation between the quality of reduction and functional outcomes.
The average recommendation for operative reduction of the tibial plateau is <2 mm80. The knee seems to be able to tolerate residual incongruence of >3 mm, at least on the tibial side61,63. One explanation for this phenomenon is that the menisci provide a cushion that reduces the pressure forces due to step-off, which may slow the progression toward posttraumatic arthritis. Despite the fact that patients may do well clinically with ≥4 mm of incongruity, the authors strongly recommend as close to anatomic reduction as achievable to enhance the opportunity for excellent clinical results.
In contrast, the characteristics of the tibiotalar joint are much different from those of the knee: cartilage at the tibiotalar joint is thinner and less elastic than the cartilage at the knee15, there are no protective structures like menisci, and the joint contact forces are higher due to the smaller surface area. These differences in functional anatomy may begin to explain why a distal tibial fracture, in general, does poorly in comparison with a fracture at the tibial plateau. Further studies need to be performed to determine if the quality of reduction affects outcome following distal tibial fractures.
Despite the limited outcomes research on calcaneal fractures, it appears that achieving an anatomic reduction may portend better results. It is critical that further studies be performed on intra-articular calcaneal fractures to definitively establish the importance of anatomic reduction on functional results. On the basis of the studies presented, we recommend that surgeons pursue an anatomic reduction of calcaneal fractures to give the patient the best opportunity for good long-term results (Table VII).
Source of Funding: No external funding was utilized for this investigation.
Investigation performed at the Department of Orthopaedic Surgery, Regions Hospital, St. Paul, Minnesota
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
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