POSTGRAD. MED. J. (1966), 42, 16

MOVEMENT OF THE LESSER TROCHANTER IN

PERTROCHANTERIC FRACTURE

K. N. NORCROSS, M.A., F.R.C.S. J. R. PEARSON, F.R.C.S.

The Robert Jones and Agnes Hun t Orthopaedic Hospital, Oswestry.

INTERNAL fixation of pertrochanteric and inter-trochanteric fractures of the femur has beenregularly practised in this country for the pasttwenty years. In spite of this method of treat-ment, many patients are slow to recover thepower of active hip flexion.

Case ReportA man of eighty-four sustained a pertrochanteric

fracture of the right femur which was fixed with aJowett blade plate. Four weeks after operation hesuddenly complained of pain in the right knee forwhich no physical abnormality in the knee could bediscovered; however, the ability to perform a straightleg raise was lost. A radiograph of the hilp jointshowed a shift of the lesser trochanter as comparedwith the radiograph taken immediately after theoperation (Figs. 1 and 2). A further month elapsedbefore he recovered the ability to raise the straightleg against gravity.This report suggested that the integrity of the

attachment of the ilio-psoas muscle determinedthe power of hip flexion. In fifteen patients whohad sustained pertrochanteric and intertrochan-teric fractures of the femur which had beenfixed with a pin and plate, the power of hipflexion was measured at weekly intervals. Themeasurements were difficult to standardize be-cause the patients were old, and their generalimprovement did not occur steadily. The dia-gram '(Fig. 3) shows the method of measuringthe power of hip flexion. Particular attentionto the following details in order to standardizethe procedure were made:With the patient lying on her side the sling

was placed at the correct position on the thighas distal as 'possible; the knee was flexed

and the foot supported clear of the mattress;the resistance produced by the spring balancewas such as to retain the hip in neutral flexion-extension; the patient was encouraged to flexthe hip without a jerking motion.The measurements were recorded without

detailed knowledge of the fracture being knownto the observer, and the results were assessedseparately.

ResultsIn eight patients the lesser trochanter was

avulsed from the shaft, and in seven the lessertrochanter was 'not avulsed.Two characteristic graphs are shown of the

power of hilp flexion (Figs. 4 and 5), showingthe course of recovery with an intact lessertrochanter (Table 1) and with displacement ofthe lesser trochanter (Table 2). The forceexerted on the spring balance is measured inpounds.

TABLE 1

POWER OF HIP FLEXION (POUNDS) MEASURED WEEKLYAFTER INTERNAL FIXATION OF PERTROCHANTERICFRACTURE. LESSER TROCHANTER INTACT.

(A.B., aged 45. Sound leg 50 lbs.)Week: 1 2 3 4 5 6 7 8 9 10 11Force: 7 14 19 22 25 32 40 45 50 50 45

1248 lbs.

TABLE 2

POWER OF HIP FLEXION '(POUNDS) MEASURED WEEKLYAFTER INTERNAL FIXATION OF PERTROCHANTERIC FRAC-TURE. LESSER TROCHANTER AVULSED.

(F.G., aged 87. Sound leg 25 lbs.)Week: 1 2 3 4 5 6 7 8 9 10 11 12Force: 0 0 3 4 8 18 22 25 27 23 118 231bs.

The characteristic features of the recoveryof the power of hip flexion when the lessertrochanter is avulsed are the diminution ofpower in the first four or five weeks, and therapid rise to normal power by the eighth orninth week, as compared with hips in whichthe lesser trochanter is not avulsed.

Experiments were performed upon thecadaver to determine the amount of movementof the lesser trochanter. Radiographs were takenafter division of the lesser trochanter and dis-placing it to a comparable positiont as seen inthe living (Fig. 6). it was found that the amountof movement of the lesser trochanter was fivecentimetres.

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NORCROSS and PEARSON: Pertrochanteric Fracture

.............................. ....... ...~~~ ~~~~~~~~~.... .... .... ........W 0;

(a) (b)FIG. 1.-Antero-posterior and lateral radiograph of pertrochanteric fracture fixed with a pin and plate taken one

day after operation.

...............

(a) (b)FIG. 2.-Antero-posterior and lateral radiograph taken one month after operation showing proximal movement of

the lesser trochanter as compared with Fig. 1.

17

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January, 1966

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18 POSTGRADUATE MEDICAL JOURNAL January, 1966

~iil ........4.....i~ 41IJ41:O~l!~~l~~~~i·A. ,.l.lllI~raAS

le.44 4d

FIG. 3.--Method of measurement of the power ofhip flexion with the patient lying on her sideusing a spring ,balance.

NORMAL50-

45

40 :

35

30

25-

20: /

15

10

a 3 .6 7 I

/ 2 3 + 5 6 7 6 9 /O /I 12WEEKS

FIG. 4.-Graph showing the recovery of the powerof hip flexion after pertrochanteric fracture after,internal fixation of the fracture. Lesser trochanternot avulsed. Vertical ordinate spring balancemeasurement in pounds.

NORMAL5

20/

1 2 3 + 5 6 7 8 9 1o 1' /2

WFTIKITFIG. 5.-Graph showing the recovery of the power of

hip flexion after pertrochanteric fracture afterinternal fixation of the fracture. Lesser trochanteravulsed. Vertical ordinate. Spring balancemeasurement in pounds. (Normal is oppositelimb).

Discussion

Avulsion of the epiphysis of the lesser tro-chanter by the pull of the ilio-psoas muscle isnot uncommon. After the epiphysis is fusedat the age of eighteen years, avulsion fractureof the lesser trochanter is exceptional (Watson-Jones, 1955). The application of a pin andplate to pertrochanteric and intertrochantericfractures has resulted in mobilisation of the limband more activity on the part of the patientmuch earlier than when these fractures weretreated conservatively. When there is delay inthe ability to use the limb and even to walkafter operation, avulsion of the lesser trochantermay be a factor.

SummaryAvulsion of the lesser trochanter is associated

with pertrochanteric and intertrochantericfractures.The power of active hip flexion is always

decreased in the first month after internal

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January, 1966 NORCROSS and PEARSON: Pertrochanteric Fracture 19

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FIG. 6.-Antero-posterior radiograph after separatingthe lesser trochanter from the femur and dis-placing it proximally in the cadaver.

fixation of the fracture but recovers by theeighth week. Movement of the lesser trochantermay be as much as five centimetres.

REFERENCEWATSON-JONES, R. (1955): Fractures and Joint

Injuries. 4th ed. Vol. II, p. 653. Edinburgh andLondon: E. & S. Livingstone.

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