Post-traumatic osteoporosis and algodystrophy after external fixation of tibial fractures

Injury (1993) 24,(6), 411-415 Printedin Great Britain

411

Post-traumatic osteoporosis and algodystrophy external fixation of tibia1 fractures

after

E. J. Smith, A. J. Ward and I. Watt Bristol Royal Infirmary, Bristol, UK

The incidenceof two forms of post-traumatic osteoporosisand algodystrophy in theankle region O~ZO patients with displaceddiaphysealfiacfuresof the tibia treatedwith extemal jixation were studied. Acute 1ocaliseA osteoporosis (ALO) occurred in 14 (70per cent) and 5 (25per cent) developed algodystrophy. Al0 was signijicantly lessfrequent in matched patients treated by internal /ix&ion or by external plaster-of-Paris(POP) cast. Regional osteoporosis(RO) was most common in POP patients. The presence of AL0 may indicate the developmentof algodystrophy following tibia1 fracture. Our findings suggest that external fixation wzay predisposeto AL0 and algodystrophy.

Introduction Osteoporosis occurs in up to 65 per cent of fractured limbs immobilized in plaster (Jones, 1969). Regional osteoporosis (RO) usually presents as a uniform loss of trabecular density in the affected bones (Resnick and Niwayama, 1988). Other patterns of bone loss include band-like radiolucencies in the metaphyseal’ and subchondral areas, speckled or patchy round lucencies and subperiosteal scalloping or intracortical lamellation (Jones, 1969; Arnstein, 1972). These latter changes of ‘acute localized osteoporosis’ (ALO) may be of more rapid onset than RO (Resnick and Niwayama, 1988). Algodystrophy (reflex sympathetic dystrophy syndrome, Sudeck’s atrophy) is a clinical disorder characterized by pain, tenderness, swelling or vasomotor changes in which marked osteoporosis appears in radiographs (Dour-y et al., 1981; Kozin et al., 1981a). It remains uncertain whether post-traumatic osteoporosis results from the injury, its subsequent treatment or algodystrophy. The aim of this study was to determine the incidence of algodystrophy and the type of post-traumatic osteoporosis occurring in patients with tibia1 fractures treated by external fixation. It was our impression that in these patients there was an unexpected high incidence of pain, swelling and osteoporosis in the ankle and foot compared with tibia1 fractures treated by cast immobilization or internal fixation.

Patients and methods A series of 20 consecutive patients with displaced diaphyseal fractures of the tibia who were treated with the Dynabrace External Fixator System (Smith and Nephew Medical Limited) underwent prospective clinical and radiographic assessment. This external fixator group (Extfix) 0 19% Butterworth-Heinema 0020-1383/93/060411-05

Ltd

comprised 14 males and six females with a mean age of 34 years (range 18-73 years). The sites of fracture were three cases in the upper third, II in the mid-third and six in the lower third of the diaphysis. There were five closed and 15 open fractures; the latter being classified according to Gustilo and Anderson (1976) as ten grade I, three grade II and two grade III cases. The patients were examined at 2-weekly intervals while the external fixator was being used and d-weekly intervals after removal. Clinical assessment was made of pain, tenderness, swelling, stiffness and vasomotor instability in the ankle or foot. Weight bearing and walking abilities were recorded. ‘Definite algodystrophy’ was diagnosed by the criteria used in the hand by Kozin et al. (1981a). Plain anteroposterior radiographs of the tibia and ankle joint were obtained at the time of injury and, subsequently, at 2-d-weekly intervals until discharge. The radiographs were assessed for post-traumatic osteoporosis by an experienced radiologist (IW) on two separate occasions, blind to the clinical assessment. Acute localized osteoporosis (ALO) appeared distant to the fracture site as a transverse radiolucent band in the trabecular bone of the metaphyseal region of the distal tibia and fibula with associated changes in the tarsal bones. Severity of change was graded as follows: 0 = none; + = mild; + + = marked. In mild AL0 the metaphyseal radiolucent banding was usually associated with some subchondral resorption in the tibia and talus with adjacent speckled or patchy radiolucencies of bone. In marked AL0 the metaphyseal banding, subchondral resorption and adjacent epiphyseal speckled appearances were more severe, with associated resorptive changes of intracortical tunnelling or lamellation in the cortical bone (Fiere I 1. Regional osteoporosis (RO) appeared throughout the bones with cortical thinning and a simplified trabecular pattern resembling diffuse rarefaction or ‘wash-out’ of bone (Figure 2). The time of onset and duration of any observed radiographic changes were noted. The presence or absence of significant soft-tissue swelling of the ankle was recorded. The severity of the fracture was graded by the degree of displacement and comminution using the modified Ellis classification (Leach, 1984)(TableI). The distance from the ankle joint line of the lowermost tibia1 fixation pin was measured on the postoperative radiograph. Two further treatment groups of 20 patients with displaced diaphyseal fractures of the tibia were selected by

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Figure 1. Acute localized osteoporosis of the ankle after tibia1 fracture. a, Mild (+) AL0 - the characteristic features are transverse metaphyseal osteopenia in the tibia and fibula, subchondral resorption and adjacent speckled or spherical radiolucenties of bone in the tibia and talus. b, Marked (+ +) AL0 - the osteopenia is more severe with diffuse metaphyseal banding, marked subchondral resorption, speckled radiolucent areas and associated intracortical tunnelling or lamellation.

Table I. Modified Ellis classification of the severity of fracture

(Leach, 1984) Grade Minor Moderate Severe

Displacement Horizontal displacement of less than 50% of diaphyseal diameter Horizontal displacement of greater than 50% of diaphyseal diameter Completely displaced

Figure 2. Regional osteopenia of bone; there is a reduction in the overall density of the bones with cortical thinning and a simplified trabecular pattern.

Comminution Nil or minor Nil or minor

Table II. Incidence and severity of acute localized osteoporosis (ALO) of the ankle in the three treatment groups

Major

matching for age, sex and site of fracture with the Extfix group. The internal fixation group (Plate) were managed by internal fixation using A0 plating techniques. There were 15 closed fractures and five were open, of which four were grade I and one was grade II. The external cast group (POP) were treated by closed reduction and immobilization in external casts. There were 15 closed and five open fractures, of which four were grade I and one was grade II. Their radiographs were assessed by the same method as described above to allow a comparison of the relative incidence and nature of post-traumatic osteoporosis with different treatment modalities.

Results In the Extfix group, ten patients complained of transient or more prolonged pain and stiffness of the lower tibia, ankle and foot with corresponding radiographic changes of ALO. Of these, five had ‘definite algodystrophy’ (Kozin et al., 1981a) with pain, tenderness and swelling or vasomotor changes in the ankle and foot (F&m 3). Symptoms resolved in all cases within IZ weeks of onset. Four patients with radiographic changes of AL0 were asymptomatic. None of the four patients with RO had clinical features of algodystrophy.

Severity ofAL

Extfix (N=ZO)

P/ate (N=ZO)

POP (N=ZO)

++ +

9 5

2 4

1 5

6 (30%)

6 (30%)

Total

14 (70%)

In the Extfix group, 14 patients (70 per cent) developed mild ( + ) or marked ( + + ) AL0 compared with 6 (30 per cent) in each of the other two treatment groups (TableII). This increased incidence of AL0 in the Extfix group was significant when compared with the other groups (x2 test with Yates’ correction, x2 = 7.135, P< 0.01). Furthermore, the incidence of marked changes (+ +) was significantly greater in the Extfix group comparediwith the other groups (x2 = 9.492, P< 0.01). The overall incidence of AL0 in the three treatment groups was 26 (43 percent). The incidence of RO in the Extfix patients was 4 (20 per cent) compared with 8 (40 per cent) in the POP group and 2 (10 per cent) in the Plate group. The overall incidence of RO was 23 per cent in the three groups. There was no apparent association between AL0 and RO in the 60 patients studied. The severities of the displacement and comminution of the fractures were similar in all three treatment groups with similar numbers of minor, moderate and severe modified

Smith et al.: Osteoporosis

and algodystrophy

after fixation of tibial fractures

413

Figure 3. Algodystrophy

of the right lower leg and foot 8 weeks after tibia1 fracture treated with external fixation, a, Anteroposterior and b, lateral radiographs of the affected leg showing marked changes of AL0 in the distal tibia and fibula, talus and adjacent tarsal bones. c Acute phase. d, Delayed phase g9mTc-HDP radioisotope scan posterior views of both legs showing initial diffuse activity of the right side indicating increased blood flow and later profound increased uptake of isotope throughout the right tibia, ankle and foot not restricted to the sites of fracture or fixation pins.

Ellis grades (T&leIII). There was no correlation of the incidence of AL0 and the severity of fracture in the three treatment groups. In the Extfix group, seven out of eight patients with minor grades of fracture developed AL0 compared with six out of the ten moderate and one out of the two major grade cases. The incidence of AL0 was not influenced by the severity of the open fracture (Figure 4). In the Extfix group, there was a preponderance of AL0 in patients with closed fractures, with all five being affected. Out of 10 patients with grade I open fractures, seven developed AL0 compared with only one of each of the grade II and grade III open fractures. The onset of AL0 occurred at a median of 6 weeks after injury (range 3-16 weeks) compared with 12 weeks (range 8-20 weeks) for RO (Mann-Whitney test, P< 0.001). The

15 kl I) S z

10

5

0 No AL0 Closed

Table III. Severity of fracture in the three treatment groups

(modified Ellis classification) Severity Minor Moderate Severe

Extfix

Plate

POP

8 10 2

9 10 1

11 9 0

Table IV. Incidence of acute localized osteoporosis (ALO) by site

of fracture and treatment group

No AL0 Open Grade Type

I

No AL0 Open Grade II and

III

of fracture

Figure 4. Incidence and severity of acute localized osteoporosis

(ALO) in closed and open fractures. 0 None,. 0 + + ALO.

+ALO.

N

period of resolution was prolonged and incomplete in both AL0 and RO up to 6 months after fracture. There were no significant differences in the frequency of AL0 of the ankle as related to the sites of fracture in the tibia (TublelV). There was no apparent relationship of posttraumatic osteoporosis of the ankle region and the age or sex of the patients or the distance from the ankle joint of the screws (Plate group) or the pins (Extfix group).

Site of tibia/ fracture

Treatment Extfix Plate POP Total (%)

group

Lower (N= 78) 5 2 3 10 (56)

Middle (N=33) 7 3 3 13 (39)

Upper (N=9) 2 1 0 3 (33)

Discussion Acute localized osteoporosis is more frequent than RO in patients treated by external or internal fixation. AL0 is a more acute form of osteoporosis than RO (Resnick and Niwayama, 1988) with median times of onset of 6 and 12 weeks after injury, respectively. However, the diffuse nature of RO may make it more difficult to detect on radiographs

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unless more than 30 per cent of bone mass has been affected (Feist, 1970). Nonetheless, the observation that regional osteoporosis is common in patients with tibia1 fractures treated in plaster casts is confirmed (Jones, 1969). These radiographic changes of osteoporosis did not fully resolve in the 3-6 month period of study. Previous studies of bone mineral loss after tibia1 fractures (Nilsson, 1966; A;lderson and Nilsson, 1979) and ankle fractures (Finsen and Benum, 1989) confirm these findings. Steinbach (1964) described irreversible radiographic changes of disuse osteoporosis up to 9 years after tibial fracture. The persistence of osteoporosis may predispose to further fractures in the affected limb (Sarangi et al., 1992). We found no relationship between post-traumatic osteoporosis and the patient’s age, sex or site of tibial fracture, nor the distance from the lowermost pin or screw to the ankle joint. This contrasts with the report by Jones (1969) that osteoporosis was related to the age of the patient and the period of immobilization in a POP cast. The significance of the AL0 form of osteoporosis is controversial. The radiographic patterns may be related to changes in vascularity in affected areas of the bone (Trueta, 1963; grower and Allman, 1982). The appearances have been associated by some authors (Resnick and Niwayama, 1988) with the condition of algodystrophy, particularly the presence of severe speckled or patchy osteoporosis (Brailsford, 1936; Plewes, 1956) or metaphyseal banding (Stem, 1936). Others believe the appearances are indistinguishable from those of disuse osteoporosis (Stevenson, 1952; Steinbach, 1964; Jones, 1969; Genant et al., 1975), though they often occur rapidly and severely with marked cortical changes, such as endosteal resorption and intracortical striations, in algodystrophy (Genant et al., 1975). Our clinical findings suggest that the significantly increased incidence of AL0 in the Extfix patients is related to the occurrence of algodystrophy, though this cannot be substantiated without detailed clinical assessment in the Plate or POP groups. Of the 14 Extfix patients with ALO, five had ‘definite’ algodystrophy (Kozin et al., 198la). This high incidence of algodystrophy (25 per cent) after tibia1 fracture has not been reported previously though the same rate was reported recently in the hand after Colles’ fractures (Atkins et al., 1989). The aetiology of AL0 and algodystrophy does not appear to be related to the severity of the tibial fracture since all three treatment groups were similar. Although open fractures were more common in the Extfix group, AL0 occurred predominately in those with closed fractures. Local bone mineral loss after fracture is thought not to be related to the type or severity of fracture (Ulivieri et al., 1990). This suggests that the mode of treatment, the external fixator, is a likely aetiological factor in these otherwise closely matched patients. The mechanism of causation of the metaphyseal bone response remains unknown. The diagnosis of algodystrophy requires a high degree of awareness of the condition since the severity varies from barely perceptible forms, clinically within normal limits, to the classic severe form (Doury et al., 1981). The use of dolorimetry in measuring tenderness in the foot has recently been reported to aid the diagnosis of algodystrophy (Sarangi et al., 1991). Our study highlights that the radiographic pattern of AL0 is suggestive of algodystrophy. In suspected cases bone scintigraphy is recommended as the characteristic finding in algodystrophy is increased activity in multiple joints of the affected extremity (Genant et al., 1975; Kozin et al., 198Ib) (Figure3). However, more

localized patterns of increased or even decreased activity may be seen (Doury et al., 1981). We conclude that post-traumatic osteoporosis and algodystrophy of the ankle and foot are common in patients with tibial fractures treated with external fixation. One should be aware of the likely development of AL0 and its frequent association with algodystrophy. Further studies are required to determine if varying the method of fracture treatment will alter the incidence or severity of posttraumatic osteoporosis and algodystrophy.

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Smith et al.: Osteoporosis and algodystrophy after fixation of tibial fractures

Sarangi P. P., Ward A. J., Smith E. J, et al. (1991) The use of dolorimetry in the assessment of post-traumatic algodystrophy of the foot. The Foof I, 157. Steinbach H. L. (1964) The roentgen appearance of osteoporosis. Radial.Clin.North Am. 2. 191. Stem W. G. (1936) Acute transverse bone atrophy. ]. Bone Joint Surg. IS, 659. Stevenson F. H. (1952) The osteoporosis of immobilization in recumbency. I Bone]oinf Surg.34B, 256. Trueta J. (1963) The role of the vessels in osteogenesis.]. BoneJoint Surg.45B, 402.

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Ulivieri F., Bossi E., Azzoni R. et al. (1990) Quantification by dual photonabsorptiometry of local bone loss after fracture. Clin. orthdp. 250,291.

Paper accepted

22 January

1993.

Requests for reprinfsshod be aa%essed to: Mr E. J. Smith FRCS, Consultant Orthopaedic Surgeon, Department of Orthopaedic Surgery, Glenfield General Hospital, Leicester LE3 9QP, UK.