Analysis of muscle function in the lower limb after fracture of the diaphysis of the tibia in adults

Analysis of muscle function in the lower limb after fracture of the diaphysis of the tibia in adults

Gaston, P

We examined the recovery of power in the muscles of the lower limb after fracture of the tibial

diaphysis, using a Biodex dynamometer. Recovery in all muscle groups was rapid for 15 to 20 weeks following fracture after which it slowed. Two weeks after fracture the knee flexors and extensors have about 40% of normal power, which rises to 75% to 85% after one year. The dorsiflexors and plantar flexors of the ankle and the invertors and evertors of the subtalar joint are much weaker two weeks after injury, but at one year their mean power is more than that of the knee flexors and extensors.

Our findings showed that age, the mode of injury, fracture morphology, the presence of an open wound and the Tscherne grade of closed fractures correlated with muscle power. It is age, however, which mainly determines muscle recovery after fracture of the tibial diaphysis.

J Bone Joint Surg (Br) 2000;82-B:326-31.

Received 74 January 1999; Accepted after revision 1 September 1999

When treating a severely-injured limb the final outcome is usually determined by the extent of the injury to the soft tissues. There have been few reports on the recovery of muscle strength after fractures of the lower limb. Of these, most have been concerned with muscle recovery after fractures of the femur rather than of the tibia,l 4 but the latter are much more common and tend to affect younger patients, many of whom are keen to return to sports and other activities 5 We have examined the recovery of muscle groups of the lower limb after fracture of the tibial diaphysis with particular reference to the age of the patient, the mechanism of injury and the type of fracture.

Patients and Methods

Between June 1994 and November 1996, 130 patients with isolated fractures of the tibia and fibula treated by intramedullary fixation were entered into the study. We excluded multiply-injured patients and those with more than one fracture in the limb, since their functional recovery would be affected by the extent and severity of other injuries, and patients who were unable to co-operate with the study protocol or who lived outside the local area. Of the 130, 30 failed to attend for follow-up, leaving 100 in the study.

There were 81 men and 19 women with a mean age of 30.6 years (13 to 64). There were 87 closed and 13 open fractures. According to the AO classification6 67 fractures were type A, 22 were type B and 11 were type C. Of the 87 closed fractures, eight were Tscherne7 CO, 63 were Cl, 14 were C2 and the remaining two were C3. All fractures were classified by one consultant (CCB) to avoid interobserver variation. Open fractures were treated by debridement and primary nailing followed by re-exploration of the wound 36 to 48 hours after injury, with soft-tissue cover being carried out at the second procedure or shortly after. Closed fractures were treated by primary nailing 8’9 A reamed GrosseKempf nail was used in all cases. Physiotherapy was started on the day after operation and weight-bearing was allowed as soon as it could be tolerated.

Muscle function was assessed using a Biodex dynamometer (Biodex Medical Systems Inc, New York) at 2, 6, 10, 14, 18, 26, 39 and 52 weeks after injury to determe isokinetic peak torque, total work and the average power for knee flexion and extension, ankle dorsiflexion and plantar flexion and subtalar inversion and eversion. Each test consisted of an active period of warm-up followed by six repetitions carried out as forcefully as possible at a slow speed (120/s in the knee and 600/s in the ankle and subtalar joints). After a rest the patients performed 15 fast repetitions (240/s in the knee and 120/s in the ankle and subtalar joints). Both lower limbs were tested with the knee first and then the ankle and subtalar joints. The values for the uninjured limb were considered to be the expected muscle strength for the patient; those of the injured limb were expressed as a percentage of the readings for the uninjured limb. All tests were carried out by a research physiotherapist without knowledge of the severity of the injury.

The Kruskal-Wallis, Wilcoxon rank-sum and Spearman rank correlation tests were used. Multiple regression was used to test whether different predictors were independently related to outcome.


In both the injured and uninjured limbs peak torque, total work and mean power correlated strongly with each other (correlation coefficients 0.62 to 0.99) as did the values at slow and fast speeds (correlation coefficients 0.83 to 0.98). Muscle recovery is therefore presented as the peak torque at the slow isokinetic speeds (120 deg/s in the knee and 60 deg/s in the ankle and subtalar joints).

The mean percentage recovery of muscle function for the knee extensors and flexors after fracture of the tibial diaphysis is shown in Figure 1. This indicates that they have about 40% of normal power two weeks after fracture, rising to between 75% and 85% of normal at one year, with the return of power of the flexors being better than that of the extensors. The mean percentage recovery of ankle plantar flexion and dorsiflexion is shown in Figure 2. Plantar flexion is weak two weeks after injury but improves quickly, and the power of plantar flexion and dorsiflexion is between 90% and 100% of normal by one year. Plantar flexion is very similar to eversion and inversion of the subtalar joint in that it is weak at two weeks, but improves quickly over the initial 15 to 20 weeks (Fig. 3).

Tables I to III give the effect of age, mode of injury, AO type, the presence of an open wound and the Tscherne grade of closed fracture on recovery for the three groups of reciprocal muscles at 26 and 52 weeks. Increasing age is associated with lower recovery of the muscle although this correlation is only statistically significant in the muscle groups of the ankle (p

In AO type-C fractures muscle recovery tends to be less than in type-A or type-B fractures, although the correlation between AO type and recovery is only statistically significant when measuring the power of subtalar inversion (p

Open fractures are associated with less recovery in all muscle groups (Tables I to III), although statistical significance is only reached with knee flexion and ankle dorsiflexion, remaining at p

In closed fractures the increasing Tscherne grade tends to be associated with less recovery although this is only statistically significant with knee extension (p

The mode of injury and muscle recovery are significantly related to the power of plantar flexion of the ankle (p


Few studies have analysed muscle function after fracture of the lower limb. Some authors have examined the function of the quadriceps and hamstrings after fracture of the femur1-4 but at a variable time after injury. Most have included patients treated by various techniques and with other injuries which would affect the outcome. Others have examined muscle strength in the uninjured limb and have reported only the static isometric measurement.l io We can find no previous study which has prospectively analysed dynamic muscle function after fracture of the tibia. The Biodex dynamometer gives accurate reproducible assessment of muscle function.11,12

There is some debate about the use of the uninjured limb as a control. ’14’13 perrin has shown in normal individuals and most athletes that there are few bilateral differences in the muscle power of the lower limbs. As with other authors, we have found a slight increase in the strength of the uninjured limb with time4 with improvement of up to 25% being noted, but this increase tended to reach a plateau early. Our study also confirmed that there is a high correlation between peak torque, total work and mean power between the two test speeds. 1,15,16

Figures 1 to 3 illustrate the speed of recovery in the three reciprocal muscle groups acting on the relevant joints, and show that the knee flexors and extensors are not initially affected as much as the groups which act directly across the site of the fracture. They have only about 40% of normal function two weeks after fracture but by one year function is between 75% and 85% of normal. By contrast, the function of the muscles acting across the site of the fracture is less at two weeks, but at 15 to 20 weeks after injury it has overtaken that of the muscles controlling the knee; this difference is still seen at one year.

Our findings have shown that after a fracture of the tibial diaphysis physiotherapy should concentrate on the flexors and extensors of the knee as well as on muscles below the joint. They indicate why most patients take a considerable time to return to sporting and other strenuous activities.

Shaw, Gustilo and Court-Brown17 have shown that young men take a mean of 26 weeks to return to football training and 40 weeks for competitive football. By 26 weeks young footballers with Tscherne CO or Cl fractures have regained about 65% to 70% of function of their knee muscles and about 85% to 90% in those controlling the ankle and subtalar joints.

There are many factors which influence the return of muscle function, the most significant being the degree of direct damage, which is severe in Gustilo type-IIIb fractures. There were only 13 open fractures in our series, and we were unable to correlate the Gustilo fracture type with muscle function. Despite this Tables I and II indicate that knee flexion and ankle dorsiflexion are significantly affected by the presence of an open wound and previous authors have drawn attention to joint stiffness in Gustilo type-III fractures associated with severe muscle damage 9m

Age is also a major determinant of outcome even although it may not be independent of other factors. In a previous publication we have shown that union was significantly affected by age and our data suggest that this is also the case in muscle recovery. This observation explains the correlation between subtalar inversion and the AO type, as well as that between plantar flexion of the ankle and the mode of injury, and knee extension and the Tscherne grade. Fractures in young adults tend to be more simple than those occurring in the older population. CourtBrown and MCBirnie showed that the mean age of occurrence of AO type-A fractures was 33.6 years compared with 39.5 years for type B and 44.3 years for type C. They also showed that increasing severity of closed fractures of the tibia, as detailed by the Tscherne classification, was associated with increasing age. The influence of age also explains why patients who sustain a tibial fracture in a simple fall have poor muscle recovery. Court-Brown and McBirnie5 have shown that the mean age of patients who sustain a fracture of the tibia in a simple fall is 57.4 years compared with 45.1 years for pedestrians in a road-traffic accident (RTA), 23.8 years for footballers and 29.5 years for the `other’ group. While the RTA group may have a worse soft-tissue injury, the `simple fall’ group are older and the net effect is that muscle recovery in these two groups is very similar as is seen in Figure 8. The association between age and mode of injury is also demonstrated statistically in that neither of these factors correlates independently with the power of plantar flexion at 52 weeks.

Our findings have shown that muscle function is slow to recover after fracture of the tibial diaphysis. There are many factors which influence recovery of which the most important is age. It is possible that some of the significant results in Tables I to III may have arisen by chance because of the number of different tests being carried out. All the muscles which control the ankle and subtalar joints recover quickly from an initially low level, but after 15 to 20 weeks the differences caused by age, muscle damage and the type of fracture become more obvious. The same is true for the flexors and extensors of the knee although they start with a higher value but fail to achieve the same level of recovery.

The authors gratefully acknowledge the generous donation from the Scottish Orthopaedic Research Trust into Trauma which allowed them to complete this project.

No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.


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P. Gaston, E. Will, M. M. McQueen, R. A. Elton, C. M. Court-Brown From the Royal Infirmary of Edinburgh, Scotland

P. Gaston, FRCS Ed, Orthopaedic Registrar

E. Will, MCSP, Research Physiotherapist

M. M. McQueen, MD, FRCS, Consultant Orthopaedic Surgeon C. M. Court-Brown, MD, Consultant Orthopaedic Surgeon

Department of Orthopaedic Surgery, Royal Infirmary of Edinburgh NHS Trust, Lauriston Place, Edinburgh EH3 9YW, UK.

R. A. Elton, PhD, Statistician

5 Wilton Road, Edinburgh EH16 5PN, UK. Correspondence should be sent to Mr C. M. Court-Brown.

Copyright British Editorial Society of Bone & Joint Surgery Apr 2000

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