Injury Clinic
Sports Medicine 9 (5): 311 -316. 1990 0112-1642/90/0005-0311/$03.00/0 © ADIS Press Limited All rights reserved. SPORT2268
The Treatment of Avulsion Fractures of the Tibial Tuberosity in Adolescent Athletes P. Balrnat, P. Vichard and R . Pern Service d'Orthopedie-Traumatologie, H6pital Jean Minjoz,
Besan~on ,
France
Contents
Summary ............ ...................................... ....................................... ........ ................................... 311 I. Definition ............ ......................... ......... .................................................................... ........ ..... 311 2. Classification ............................. ............................................ ...................... ........................... 312 3. Physiopathological Mechanisms of Injury ........................ .. ................................................ 312 4. Aetiology and Risk Factors ......................................... .................... .....................................314 5. Diagnosis of Injury .. .................................................................................................... .......... 315 6. Treatment ........... ........................... ......................................................................................... 315 7. Preventive Measures ................................... ............ ...................................... ........................ 316 8. Conclusion .... ....... ...... ... ....................... .......... ................ ... ................................. ........... ......... 316
Summary
Avulsion fractures of the tibial tuberosity occur mainly during sport activities and are closely related to the strains exerted on the anterior tibial tuberosity by the extension complex of the thigh. A knowledge of the mechanical aspects of these avulsions may improve understanding of the mechanisms of such injuries. In such avulsion fractures, tensile forces due to the contraction of the quadriceps complex overcome the cohesive forces within the apophyseal cartilage. A I-month cast immobilisation on an extended knee gives good results in .the management of nondisplaced fractures. In minor displacements, such immobilisations follow closed external reductions. Open reductions and stable screw fixations precede a 3-week immobilisation for displaced fractures. Long term results are regularly good in well-managed cases.
We have studied 7 cases of avulsion fracture of the anterior tibial tuberosity in adolescents in our Orthopaedic and Traumatology Department (table I), and in a review of the literature have found 73 well-documented cases of such avulsion fractures. In this article we try to explain the different types of fractures according to the mechanism of this acute injury. We believe that by being aware of certain predisposing factors and understanding biomechanical ones, we may identify adolescents at
high risk of this injury. Recommendations given to these 'high-risk' adolescents may prevent such injuries.
1. Definition Avulsion fractures of the tibial tuberosity are rare acute traumatic injuries occurring in adolescent athletes during the practice of certain specific sports where the extensor complex of the thigh is highly solicited.
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Table I. Treatment data for 7 patients with avulsion fractures treated by the authors. All patients had complete recovery Patient
Age (years)
Sex
16 2
Type of fracture
Activity
Male
IA
High jump
16
Male
IIIB
High jump
3
16
Female
iliA
Gymnastics
4
15
Male
liB
High jump
5
16
Male
IIIB
Handball
6
17
Male
liB
High jump
7
14
Male
lilA
High jump
2. Classification Several classifications have been proposed for these injuries in the literature. The classification of Salter and Harris (1963) is inappropriate here since such avulsion fractures are not caused by compression forces. The classification proposed by Watson Jones (1955) and adopted by Hand et al. (1971) does not consider the degree of displacement of the fractures and the number of detached fragments. We have used the classification of Ogden et al. (1980) which has the merit of considering both the different lines of fractures and the degree of displacement of the avulsed fragments (fig. I).
3. Physiopathological Mechanisms of Injury The physeal cartilage of the tibial tuberosity presents a particular fibrocartilaginous histological structure, well-adapted to stress in tension. Just prior to preossification, the fibrocartilaginous tissue of the physeal cartilage is replaced by an en-
Treatment
Follow-up (months)
Cast immobilisation for 1 month 2 screws; cast immobilisation for 3 weeks 1 screw, cast immobiiisation for 3 weeks 1 screw, cast immobilisation for 3 weeks 2 screws, cast immobilisation for 3 weeks 1 screw, cast immobilisation for 3 weeks 1 screw, cast immobilisation for 3 weeks
48 36
36
48
12
48
48
dochondral ossification. This endochondral ossification occurs at about the end of growth age, that is roughly at the age of 15 to 16 years in male adolescents. As mentioned above, this range of age corresponds to the ages when avulsion fractures of the tibial tuberosity mostly occur. The proximal tibial epiphysis and the tibial tuberosity develop from 2 separate ossification centres which fuse at the end of adolescence. One might think that early in adolescence, prior to fusion of these 2 centres, avulsion fractures involve only the tibial tuberosity whereas by the end of adolescence, avulsion will be more extensive, involving the proximal tibial epiphysis as well. However, our own study and the review of the literature show that the type of injury is not closely related to the age at which it occurs. Instead, the type and nature of the avulsion fracture seem dependent upon biomechanical factors. Generally, avulsion of the tibial tuberosity occurs when a violent contraction of the quadriceps tends to resist forces projecting the tibial apophysis in an opposite direction. The anterior tibial tub-
Avulsion Fractures of the Tibial Tuberosity
erosity involved in these dynamics of opposing forces around the flexion axis of the knee is submitted to considerable strains. In adolescents, the apophyseal cartilage is the point of lowest resistance, while in adults the same mechanisms are instead responsible for tendinous or muscular lesions. Avulsion of the tibial tuberosity occurs when tensile forces exerted by the quadriceps and transmitted to the anterior tibial tuberosity by the patellar tendon are greater than the cohesive forces of the apophyseal cartilage. The type of fracture seems closely related to the degree of flexion of the knee during the accident. When injury occurs near complete extension of the knee, there is an avulsion ofthe anterior tuberosity without fracture of the proximal tibial epiphysis. In this position, the tensile forces exerted on the anterior tibial tuberosity by the patellar tendon are directed proximally and anteriorly due to the thickness of the patella (fig. 2) [Kaufer 1979]. When injury occurs in flexion, biomechanical conditions result in an avulsion involving the anterior tibial tuberosity and the proximal epiphysis. Forces in this case are exerted across the tibial epiphysis (fig. 3) [Smidt 1973]. When the movement which resulted in the injury is specified in the studies, it is generally one of 4 actions: (a) springing off for a jump; (b) landing on I foot after a jump; (c) impeded extension; or (d) forced flexion. In springing off for a jump, the final impulse leads to a hyperextension of the knee just prior to leaving the ground (Dyatchkov 1968; Gombac 1971; Ozolin 1973). Tensile forces are thus exerted proximally and anteriorly as shown before. In this situation, avulsion concerns only the anterior tibial tuberosity. During the landing phase, avulsion fractures involve both anterior tibial tuberosity and the proximal tibial epiphysis. The knee is normally flexed and kinetic energy stored in the quadriceps by the elasticity of the extensor complex, acting as a shockabsorber, is transmitted by the patellar tendon to the anterior tibial tuberosity. The energy transmitted is directly proportional to the degree of flexion (Hay 1973). Forces are exerted upwards across the
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proximal epiphysis which is thus involved in the fracture. The avulsion is often fragmented. We have noted only 5 adolescents injured during landing from a jump. Four of these lesions were of type III. The fifth patient seemed to have performed a technically wrong landing because he had his knee in a nearly extended position with a contracted quadriceps. He sustained a type I lesion. In impeded extension, contraction of the quadriceps encounters opposing forces which block extension of the knee. Thus, Christie et at. (1981) cited several basketball players who were blocked in their attempt to shoot at the basket. Quadriceps contraction is opposed by a strong downwards force due to the opponent's counter, which causes an avulsion of the anterior tibial tuberosity. Hand et
IA
IIiB
Fig. 1. The classification of avulsion fractures of the anterior tibial tuberosity proposed by Ogden et al. (1980).
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al. (1971) suggested the same mechanism in a football player who was tackled, while Levi and Coleman (1976) proposed a similar mechanism for a 14-year-old boy practising 'wheeling' on a bicycle. In forced flexion, contraction of the quadriceps opposes the force generated by flexion of the knee, which closes the femorotibial angle. Watson Jones (1955) explained an avulsion fracture in a 14-yearold boy by such a mechanism. This boy fell backwards while landing from a long jump and he produced a violent contraction to regain his equilibrium. This contraction opposed the powerful flexion force due to the whole bodyweight moving backwards, producing an avulsion of the anterior tibial tuberosity.
4. Aetiology and Risk Factors 4.1 Age All cases reported in the literature, including our own, occurred in 12- to 17-year-old adolescents. Avulsion fractures occurred mostly in patients aged 15 and 16 years. 4.2 Sex Avulsion fractures of the anterior tibial tuberosity seem to occur predominantly in male adolescents. We have encountered only 4 girls in the 80 cases reported. This higher incidence in male adolescents is due to various factors, namely comparatively more intensive activity by them, participation in 'violent' sports, a more powerful quadriceps and possibly hormonal factors (Buisson 1976; Ogden & Spouthwick 1976). 4.3 Sports Jumping is a major cause of avulsion fractures of the tibial tuberosity. In the 80 cases studied here, jumping of some sort or other was responsible for 34 cases of avulsion fractures. Taken individually, high-jumping accounted for 17 fractures and basketball was responsible for 18 fractures. In highjumpers, avulsion occurred mainly during 'springing otT'. Other sports such as football, running and
Fig. 2. Knee in extension. Force (F) acts anteriorly and proximally. K = fulcrum.
gymnastics were less frequently encountered. We have noted one case during skate-boarding. 4.4 Risk Factors
4.4. J Osgood Schlatter's Disease In the reviewed series, 16 adolescents had suffered from an ipsilateral, controlateral or bilateral Osgood-Schlatter's disease. There seems to be a relationship between Osgood-Schlatter's disease and avulsion fractures of the tibial tuberosity. Ogden and Southwick (1976) believe that the structural modifications of the physeal cartilage in Osgood Schlatter's disease are responsible for alterations in the biomechanical response of this cartilage during strains transmitted by the patellar tendon. Bowers (1981) goes even further to conclude that avulsion fractures of the tibial tuberosity are a complication of Osgood Schlatter's disease.
A vulsion Fractures of the Tibial Tuberosity
4.4.2 Familial Predisposition We have not come across any documented report concerning a familial predisposition for avulsion of the tibial tuberosity but Deliannis (1973) has proposed such a predisposition in reporting avulsion of the tibial tuberosity occurring in 2 brothers at the same age, both of whom had suffered from Osgood-Schlatter's disease.
5. Diagnosis of Injury The typical history of such injuries can be summarised as follows: an adolescent suddenly feels an acute pain at the anterior part of the knee during his or her sports activities. Functional disability is immediate with complete loss of active extension. Physical examination always reveals an acute pain at the anterior aspect of the knee, a complete functional disability and a swelling on the proximal anterior aspect of the tibia. Less frequently, the examiner may recognise an ascended patella or a depressible patella due to intra-articular bleeding, or may feel a sharp-edged subcutaneous fragment. Sagittal x-rays will generally confirm clinical diagnosis (Hulting 1957). They clearly show the avulsion fracture, the number of fragments and the importance of displacement. These findings allow a classification in one of the 6 types identified by Ogden et al. (1980). This partly influences the attitude to therapy. The only differential diagnosis that may lead to confusion is Osgood-Schlatter's disease. The disease provokes chronic pain in the anterior tibial tuberosity after repetitive efforts in adolescents from 12 to 16 years old participating intensively in sports. Functional disability is never complete and Osgood-Schlatter's disease is never accompanied by haemarthrosis. Active extension of the knee is possible though painful. x-Rays show multiple calcified spicules and sometimes tendinous calcification of the patellar tendon (Leclair 1979).
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Nondisplaced avulsions are treated by cast immobilisation with the knee in extension for 30 days. Such treatment has consistently provided good results (Ogden 1980). Sports activities should be prohibited for 90 days. Minimally displaced avulsions (types IA and lIA by Ogden's classification) may be treated like nondisplaced ones if the displacement can be reduced by external manual manoeuvres. Displaced fractures (types IB, lIB and III) should in our opinion be treated by open reduction and internal fixation. We prefer the use of screws to pins for fixation. Surgically, we believe that a medial arciform parapatellar approach (Zariczmyge 1977) gives a better covering of the screws and allows better healing. The fracture is reduced and fixed by 1 or preferably 2 screws mounted on washers. The periosteum and eventually the patellar tendon are sutured. The skin is closed with separate stitches on a suction drainage. A cast immobilises the knee in extension for 21 days. Pas-
6. Treatment Treatment depends on the type of avulsion fracture.
Fig. 3. Knee flexed. Force (F) acts across the tibia epiphysis. K = fulcrum.
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sive mobilisation and static contractions of the quadriceps begin at cast removal. Such rehabilitation should lead to an active flexion of at least 90° at the third week after cast removal. Open reduction provokes a cartilaginous fusion of the tibial apophysis, thus reducing the risk of recurrence. Patients may resume sports activities 3 months after surgery. Screws may be removed under local anaesthesia.
An understanding of simple biomechanics related to this avulsion fracture together with a knowledge of risk factors, namely Osgood-Schlatter's disease, may lead to some kind of preventive measures. Prognosis is regularly favourable in wellmanaged avulsion fractures. We recommend treatment of nondisplaced fractures orthopaedically and of displaced fractures by open reduction and stable fixation as far as possible. Such stable fixation will allow earlier rehabilitation in most cases.
7. Preventive Measures References Preventive measures should be taken by adolescents from the age of 12 who participate in certain high risk sports, such as high jump, long jump or basketball whether intensively or occasionally. We believe that such youngsters should benefit from a theoretical briefing on the different phases of a technique. Frequent video presentations might demonstrate such techniques performed by professional athletes. Sports officers might even go further in filming young athletes during the execution of their techniques in order to comment on their eventual technical faults later. If a mild form of Osgood-Schlatter's disease is encountered in a young athlete, he should be prohibited from sport activities as long as pain persists, even if such pain is bearable. If the examiner diagnoses a severe Osgood-Schlatter's disease with a painful anterior tibial tuberosity and a certain degree offunctional disability, we believe that cast immobilisation on an extended knee without weightbearing for I month is a good solution. Leclair (1979) seems to use the same period of immobilisation. Active progressive rehabilitation starts at cast removal. Full sport activities should not be reconsidered before the third month. Moreover, particular care should be given to young athletes with a past history of Osgood-Schlatter's disease.
8. Conclusion Avulsion of the anterior tibial tuberosity is a rather rare lesion encountered in adolescent athletes during certain high risk sports activities.
Bowers KD. Patellar tendon avulsion as a complication of Osgood-Schlatter's disease. American Journal of Sports Medicine 9 (6): 356-358, 1981 Buisson P. Decollement apophysaire du bassin et des membres inferieurs chez l'enfant et l'adolescent. These Medicale, Faculte de Lyon, 459, 1976 Christie MJ, et al. Tibial tuberosity avulsion fractures in adolescents. Journal of Pediatric Orthopedics I (4): 391-394, 1981 Deliannis SN. Avulsion of the tibial tuberosity: report of 2 cases. Injury 4: 341-344, 1973 Dyatchkov VM. The high jump. Track Tech 34: 1059-1061, 1968 Gombac R. The mechanics of the take-off in high jump. Medicine and Sports, Biomechanics II, pp. 232-235, Karger, Basel, 1971 Hand WL, Hand CR, Dunn WA. Avulsion fractures of the tibial tubercule. Journal of Bone and Joint Surgery 53A: 1579-1583, 1971 Hay JG. The kneumatic look at the high jump. Track Tech 53: 1697-1703,1973 Hulting B. Roentgenologic features of the fractures of the tibial tuberosity. Acta Radiologica 48 (3): 161-174, 1957 Kaufer H. Patellar biomechanics. Clinical Orthopedics 144: 5154, 1979 Leclair P. La maladie d'Osgood-Schlatter. These Medicale, Faculte Paris-Ouest, 35, 1979 Levi JH, Coleman CR. Fracture of the tibial tubercule. American Journal of Sports Medicine 4 (6): 254-263, 1976 Ogden JA, Spouthwick WD. Osgood-Schlatter disease tibial tubercule development. Clinical Orthopedics 116: 180-189, 1976 Ogden JA, Tross RB, Murphy MS. Fracture of the tibial tuberosity in adolescent. Journal of Bone and Joint Surgery 62A (2): 205-215, 1980 Ozolin N. The high jump take off mechanism. Track Tech 52: 1668-1671,1973 Salter RB, Harris WR. Injuries involving the epiphyseal plate. Journal of Bone and Joint Surgery 45A: 587-622, 1963 Smidt Cl. Biomechanical analysis of knee flexion and extension. Journal of Biomechanics 6: 79-92, 1973 Watson Jones R. Fractures and joint injuries, 4th ed., p.786, William and Wilkins, Baltimore, 1955 Zariczmyge B. Avulsion fracture of the tibial eminence: treatment by open reduction. Journal of Bone and Joint Surgery 59A (8): 1111-1114,1977
Authors' address: Professor P. Vichard, C.H.R., Hopital Jean Minjoz, Boulevard Fleming, 25030 Besan,on Cedex, France.
