What Is the Relation Between Malunion and Function for Lower Extremity Tibial Diaphyseal Fractures?

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Chapter 64 What Is the Relation Between Malunion and Function for Lower Extremity Tibial Diaphyseal Fractures?

Tibial diaphyseal fractures are one of the most common fractures of the long bones.¹ Controversy remains, however, over the best way to manage these fractures, with authors arguing not only over operative techniques but also between surgical and nonsurgical management. With any treatment, however, one thing is agreed on, there is an inherent risk for healing with some degree of residual malalignment. Indeed, in a recent systematic review of the treatment of distal-third tibial shaft fractures, for example, incidence rates of malunion (as defined by the authors of the included studies) ranged from 13.1% to 16.2% depending on treatment choice.²

Two major issues should be considered when discussing malunion. The first is what actually constitutes a malunion; that is, what are the limits of an acceptable reduction? Second, will a malunion result in any long-term adverse sequelae to the patient? If the malunion does not cause adverse sequelae, then does it actually matter? To make the argument completely circular, is it actually a malunion, radiographic issues aside? Surgeons’ definition of angular malunion has been shown to range from less than 5 to 20 degrees, and a majority of surgeons defined significant shortening as greater than 15 mm.³ However, some would argue that asymptomatic angulation be considered an anatomic deviation rather than malunion per se.⁴

This chapter discusses the literature that specifically focuses on the issue of how “malunion” of the tibial diaphysis potentially affects long-term function of the patient.

EVIDENCE

Prognostic studies address the possible outcomes of a disease or condition. In the hierarchy of evidence, a Level I prognostic study would be a prospective cohort with a ≥80% follow-up rate. One can understand it would be unethical (and difficult to obtain consent) to randomize patients into a malunion group.

For a number of reasons, reports are conflicting regarding the effect of malunion on the long-term functional outcome after tibial shaft fractures. These include a general lack of consensus as to what constitutes a malunion, retrospective reporting with incomplete follow-up and varying times of follow-up (from 10–40 years), a lack of standardized technique to radiographically measure malunion, and the use of multiple and varied functional outcome measures between studies (some that are nonstandardized and nonvalidated) (Table 64-1).

TABLE 64-1 Characteristics of Included Studies

Before assessing whether malunion of the tibial shaft affects long-term functional outcome, it is important to understand the long-term outcome in those with a tibial shaft fracture in general. Greenwood and colleagues ⁵ retrospectively reviewed 398 patients with tibial shaft fractures (it was not stated how the fractures were all treated just that “most were treated with cast therapy”) and compared these with a cohort of 1573 age- and sex-matched control subjects.⁵ Outcome measures were subjective reporting of knee pain, ability to walk 100 yards, bend, kneel, and stoop, and a general practitioner’s diagnosis of osteoarthritis. The 36-Item Short Form Health Survey (SF-36) outcome instrument was also used. Greenwood and colleagues⁵ found that patients with a tibial shaft fracture had more knee pain (odds ratio, 1.23; 95% confidence interval [CI], 1.00–1.51) and an increase in having a diagnosis of osteoarthritis (odds ratio, 1.46; 95% CI, 1.08–1.97). They also found a statistically significant incidence of a decreased ability of the patients with fractures to climb stairs, bend, kneel, or stoop. Interestingly, even though the odds ratios themselves suggested a slightly increased risk for knee pain or diagnosis of osteoarthritis, the confidence intervals either include 1 or come close to 1, suggesting that these results are trends as opposed to true statistical differences. However, because the same trend was seen throughout all domains of the outcome measures, it may be that the study was underpowered and these trends are accurate estimates of the truth.

Malunion Does Not Affect Long-Term Functional Outcome

One retrospective cohort study was identified that attempted to correlate malunion with functional outcome ⁶ (Level of Evidence II, retrospective cohort). In this study, two different groups of surgeons (community surgeons and orthopedic trauma surgeons) each treated a cohort of patients with an intramedullary nail. Between the groups it was demonstrated that the community surgeon group had a greater malunion rate.⁶

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