Orthopedic surgeons frequently provide weight-bearing recommendations to guide patient recovery following lower extremity fractures. This article discusses the available literature regarding the effects of early weight bearing on fracture healing, patient compliance with weight bearing restrictions, and the effect of different weight bearing protocols following acetabular, tibial plateau, tibial plafond, ankle, and calcaneus fractures.
Key points
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There is some evidence that patients autoregulate weight bearing based on the amount of fracture healing.
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Current methods of evaluating weight-bearing status are unreliable.
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Patient compliance with existing weight-bearing restrictions is poor.
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Studies of early weight bearing for acetabular, tibial plateau, tibial plafond, ankle, and calcaneus fractures demonstrate no increased risk for loss of reduction or nonunion compared with restricted weight bearing.
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Early weight bearing may return patients to function earlier.
Introduction
Anatomic fracture reduction, stable fixation, preservation of the surrounding soft tissues, and early mobilization are essential to the successful treatment of lower extremity articular injuries. However, because of concerns about loss of reduction, orthopedic surgeons are often hesitant to permit early mobilization of the injured limb. Restricted weight bearing after a periarticular fracture is thought to decrease the forces at the fracture site and the implant and reduce the risk of malreduction. Less mechanical stress on the implant is thought to lead to fewer construct failures and revisions. In contrast, animal studies have shown greater callus volume and faster time to union in extremities that were axially loaded as compared with those that were not loaded. Early weight bearing may also expedite the return to work and minimize the economic impact of lower extremity injury. The authors review the available clinical evidence on early weight bearing after periarticular lower extremity fractures.
Introduction
Anatomic fracture reduction, stable fixation, preservation of the surrounding soft tissues, and early mobilization are essential to the successful treatment of lower extremity articular injuries. However, because of concerns about loss of reduction, orthopedic surgeons are often hesitant to permit early mobilization of the injured limb. Restricted weight bearing after a periarticular fracture is thought to decrease the forces at the fracture site and the implant and reduce the risk of malreduction. Less mechanical stress on the implant is thought to lead to fewer construct failures and revisions. In contrast, animal studies have shown greater callus volume and faster time to union in extremities that were axially loaded as compared with those that were not loaded. Early weight bearing may also expedite the return to work and minimize the economic impact of lower extremity injury. The authors review the available clinical evidence on early weight bearing after periarticular lower extremity fractures.
Effects of restricted weight bearing
Weight-bearing restrictions can impart a significant physiologic toll on patients. In healthy patients, restricted weight bearing
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Results in a 4-fold increase in the energy expended for ambulation, when compared with full weight bearing, as measured by the physiologic cost index
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Alters gait mechanics
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Shifts the weight distribution from the forefoot and hallux to the heel
Despite concerns for the increased risk of venous thromboembolism following surgery and restricted weight bearing, available studies have demonstrated no change in the venous return in the lower extremities affected by restricted weight bearing.
Weight bearing after fracture
Clinicians routinely prescribe partial weight bearing for a lower extremity fracture in an attempt to produce an optimal mechanical environment at various stages of fracture healing. Partial weight bearing involves a gradual increase in the amount of weight that is placed on the affected limb. The partial-weight-bearing recommendation for patients varies based on the type of fracture, the extent of the injury, and the discretion of the clinician. For periarticular fractures, the standard partial-weight-bearing protocol includes 10 to 12 weeks of non–weight bearing followed by 4 to 6 weeks of progressive weight bearing whereby in the first week patients bear weight at 25% of their body weight and increase the amount of weight bearing by 25% each week until they are able to bear their full weight.
There are few studies in the laboratory setting that examine axial fracture loading in humans. In a study of 27 patients with a tibia fracture treated with external fixation and early weight bearing, the initial axial motion across the fracture site was shown to be small at 5 weeks after the fracture (mean 0.28 mm), peaked at 11 weeks (mean 0.43 mm), and then decreased at later time points as fracture healing progressed. This same group identified a similar trend when this study was performed with a larger clinical series of 45 patients.
Koval and colleagues performed gait analysis testing on elderly patients with operatively treated intracapsular and extracapsular hip fractures. Patients were allowed to bear weight as tolerated immediately after surgery. Over time, these patients voluntarily increased the weight applied to the injured limb from 51% at 1 week to 87% at 12 weeks when compared with the uninjured, contralateral limb. None of these patients experienced loss of fixation or other complications associated with immediate weight bearing.
Similarly, patients instructed to bear weight as tolerated after operative fixation of tibia fractures progressively increased axial loading across their injured extremity to around 85% that of the uninjured, contralateral extremity at 6 weeks postoperatively. All fractures successfully went on to union. The 2 patients in this series that developed a delayed union were only able to place 40% of their body weight on the affected limb at 20 weeks postoperatively.
Axial loading studies have shown that
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Initial axial motion across the fracture site is small after the fracture and decreases as the fracture healing progresses.
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No loss of fixation or other complications are associated with immediate weight bearing.
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Progressive increases in axial loading result in successful union.
Patient compliance
Available data suggests patient compliance with physician restrictions on weight bearing is poor. Standard clinical techniques to monitor weight-bearing compliance include the use of bathroom scales and a therapist estimating the load with palpation or observation. The scale has been shown to be effective; however, this is only useful for standing but not ambulation. Both palpation and observation by a therapist have proven to be unreliable, regardless of the therapist’s experience. Multiple investigations of compliance demonstrate that patients exceed the prescribed amount of partial weight bearing even when they thought themselves to have been compliant.
In efforts to improve compliance, investigators have used devices that provide real-time feedback on weight bearing. In 2 separate studies, investigators found audible feedback to be ineffective in preventing overloading of the limb because of a lag between auditory perception and motor response. Furthermore, patients trained to partially bear weight with audio feedback during their hospital stay were unable to replicate the prescription when walking unsupervised at home 21 days later.
Winstein and colleagues demonstrated that delayed verbal feedback by a therapist improved patient compliance with partial weight bearing more than device-based real-time audio feedback. Based on the available evidence, it is difficult to know if patients are actually abiding by weight-bearing restrictions, particularly outside the hospital setting.
Patients routinely
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Exceed the prescribed amount of partial weight bearing
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Are unable to make use of audible feedback for compliance
Acetabular fracture
Malreduction after an acetabular fracture has been shown to be associated with poor patient outcome and development of posttraumatic arthritis. Given the potential consequences of fixation failure with subsequent loss of reduction, few studies have been performed permitting early weight bearing after acetabular fracture.
Mouhsine and colleagues allowed elderly patients (mean 81 years of age) with column, transverse, or T-type fractures fixed percutaneously to begin unrestricted weight bearing at 4 weeks. With a minimum 2-year follow-up, the investigators reported no failure of fixation; all fractures healed an average of 12 weeks postoperatively. Similarly, 22 patients (mean 49 years of age, range 18–83 years) treated with percutaneous fixation of either an anterior column or an anterior column posterior hemitransverse fracture were permitted immediate full weight bearing postoperatively. There was no loss of reduction, and patient outcomes were similar to other reported studies at a minimum of 12 months of follow-up.
A study of mostly elderly patients who participated in early weight bearing after total hip arthroplasty for acetabular fracture reported no early loosening, hardware failure, or revision surgery for osteolysis at a mean of 8.1 years postoperatively. Based on these available studies, early weight bearing does not seem to be an excessive risk for fracture displacement in select operatively treated acetabular fractures.
Classically, postoperative protocols for acetabular fractures allow for touchdown weight bearing to decrease the joint reactive forces on the acetabulum as compared with strict non–weight bearing. However, peak pressures on the acetabulum during sit-to-stand activities performed during restricted weight bearing are nearly 3 times the forces seen during walking. Much of the force during sit-to-stand activities is directed posteriorly, whereas during ambulation more load is distributed to the superior lateral aspect of the roof.
Although few studies have examined weight bearing in patients with acetabular fractures, it is known that
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Immediate postoperative full weight bearing has not been shown to result in loss of reduction.
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Early weight bearing after total hip arthroplasty for an acetabular fracture does not result in early loosening, hardware failure, or revision surgery for osteolysis.
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Early weight bearing may not place patient at excessive risk for fracture displacement.
Tibial plateau fracture
The knee joint experiences forces between 220% and 350% of a person’s body weight during normal daily activities. A 3-mm step-off in the tibial plateau can increase the cartilage contact stresses by 75%, thus raising concerns that loss of reduction could lead to worse patient outcomes. However, the tibial plateau has been shown to tolerate some malreduction without change in outcome.
Segal and colleagues reported on a consecutive series of 86 lateral tibial plateau fractures treated operatively or nonoperatively based on an initial fracture displacement cut-off of 5 mm. Both groups were permitted to bear weight immediately in a fracture brace. The investigators reported superior outcomes among the operatively treated group; no patient in either group showed radiographic fracture displacement greater than 2 mm ( Table 1 ).
| Authors, Year | Study Type | Fracture Type | Treatment | Outcomes Measured | Results |
|---|---|---|---|---|---|
| Segal et al, 1993 | Retrospective | Lateral tibial plateau | ORIF (n = 44) and nonop (n = 42); both with WB in cast | Pain, swelling, ROM, and XR at 6, 12, 24 mo | Superior clinical outcomes in operative group; no loss of reduction in either group |
| Haak et al, 2012 | Retrospective | Lateral tibial plateau | ORIF with immediate WB (n = 12) vs delayed WB (n = 20) | Pain, reoperation, ROM, and XR at 6–8 wk | No difference in reoperations; no loss of reduction in either group |
| Solomon et al, 2011 | Prospective cohort | Lateral tibial plateau | ORIF and PWB (20 kg) (n = 7) | Fracture displacement at 2, 6, 12, 18, 26, 52 wk | Mean fracture displacement of 0.34 mm at 52 wk |
| Eggli et al, 2008 | Prospective cohort | Bicondylar plateau | ORIF and PWB (10 kg) (n = 14) | Pain, Lysholm knee score, ROM, and XR at 8, 12, 24, 52 wk | Improved knee scores; no loss of reduction |
| Ali et al, 2003 | Prospective cohort | Bicondylar plateau | Ringed EF and WB (n = 11) | ROM, SF-36, Rasmussen scale, Iowa knee, XR | 3 Pts with valgus malunion, 82% satisfactory results |
| COTS 2006 | Multicenter prospective RCT | Bicondylar plateau | Ringed EF and WB (n = 43) vs ORIF and NWB (n = 40) | HSS knee score, WOMAC, SF-36, XR, ROM | No difference in patient outcomes or loss of reduction Fewer secondary surgeries with EF and WB |
More recently, 32 patients with partial articular plateau fractures (AO 41-B) were treated operatively with locking plate fixation and prescribed immediate (n = 12) or delayed (n = 20) weight bearing postoperatively. There was no evidence of radiographic fracture displacement in either group, and both groups had a similar rate of complications. Similarly, Solomon and colleagues reported on 7 patients with Schatzker II tibial plateau fractures treated with plate fixation and immediate partial weight bearing of 20 kg. The investigators reported a mean fracture displacement of 0.34 mm at 1 year using radiostereometric analysis.
Higher-energy plateau fractures are associated with increased fracture comminution and greater soft tissue injury, both of which can distribute more load to the fixation construct and create concern for failure. Eggli and colleagues performed dual plating on 14 patients with these high-energy patterns and permitted immediate 10 kg of weight bearing. All patients achieved union by 12 weeks, and none experienced loss of fixation or subsidence as judged on radiographs.
In a study of elderly patients with bicondylar plateau treated with external ring fixator and early full weight bearing, 10 of 11 patients achieved a good result without loss of fixation; one patient experienced subsidence of the lateral plateau and underwent corrective osteotomy. In a prospective, randomized study of high-energy tibial plateau fractures, a group of 43 patients underwent fixation with ring external fixation and were permitted to bear full weight. At the minimum 2-year follow-up, there was no difference in reoperations, articular incongruity, or development of radiographic signs of osteoarthritis as compared with a cohort of 40 patients that underwent open reduction and internal fixation with restricted weight bearing.
Based on limited evidence, early weight bearing after tibial plateau fracture has been shown to
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Result in limited fracture displacement
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Result in limited loss of fixation and subsidence
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Have similar outcomes as restricted weight bearing
Tibial plafond fracture
Tibial plafond fractures are associated with high rates of posttraumatic arthritis. A 2-mm malreduction of the tibial plafond can result in a nearly 200% elevation in surrounding contact pressures. Given the concern of loss of reduction and the potential development of posttraumatic osteoarthritis, there is limited literature evaluating early weight bearing after tibial plafond fractures.
In a series of 26 patients with AO type C plafond fractures treated with dynamic external fixator and allowed partial weight bearing at 3 weeks, the investigators reported one case requiring arthrodesis and 2 cases of collapse after the fixator was removed. The remainder of the patients achieved bony union at a mean of 14 weeks.
A nonrandomized series comparing 28 patients with AO type C plafond fractures treated with locked plate fixation and non–weight bearing to 14 patients treated with the Ilizarov technique and allowed to bear weight immediately showed nonsignificant trends in the Ilizarov group toward a faster time to union (mean 24 weeks vs 39 weeks) with a trend toward higher associated rates of nonunion, malunion, and infection. Similarly, a series of 27 patients treated with internal fixation and restricted weight bearing were compared with 18 patients treated with external fixation and early weight bearing. There was no difference in postoperative articular congruity, but there were significantly more malunions in the external fixation group. In addition, several small case series of comminuted plafond fractures treated with ring external fixation and full weight bearing within 3 weeks of surgery have shown good results ( Table 2 ).
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