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Endgames Picture Quiz

An adolescent athlete with groin pain

BMJ 2014; 348 doi: https://doi.org/10.1136/bmj.g2766 (Published 28 April 2014) Cite this as: BMJ 2014;348:g2766
  1. James Thing, specialist trainee year 6, sport and exercise medicine registrar1,
  2. Chris Coates, orthopaedic surgeon 2,
  3. Mike Bundy, sports medicine physician3
  1. 1Medical Centre, Cranleigh School, Cranleigh GU6 8QQ, UK
  2. 2Royal Surrey County Hospital, Guildford, UK
  3. 3Pure Sports Medicine, Cranleigh School, Cranleigh, UK
  1. Correspondence to: J Thing thing.james{at}gmail.com

A 14 year old boy felt a mild aching discomfort in his left groin while playing rugby but still continued to play. He subsequently tackled an opponent and developed a severe pain of sudden onset in the left upper thigh and groin. A “snapping” sound was heard and he fell to the ground. He was unable to bear weight on the left leg and appeared pale, clammy, and nauseated. His pitch-side vital observations were normal and he was offered combined gaseous nitrous oxide and oxygen for pain relief. Ice was applied to the area of maximum discomfort and he was accompanied to the emergency department in an ambulance. At the emergency department he was advised that he had probably “strained” a muscle and was given conservative advice. He was discharged with crutches and analgesia.

The next day he was seen by the school doctor, who documented that he could not fully bear weight on the left leg or actively flex his leg on the examination couch. A radiograph was arranged (fig 1) and the diagnosis made on the basis of the report.

Questions

  • 1. What is the most obvious abnormality seen on the radiograph?

  • 2. What is the likely diagnosis?

  • 3. Who is most at risk of sustaining such an injury?

  • 4. What is the standard management regimen for such an injury?

  • 5. What are the indications for surgical management of this injury?

Answers

1. What is the most obvious abnormality seen on the radiograph?

Short answer

There is bony irregularity and displacement of the lesser trochanter of the left femur.

Long answer

There is bony irregularity and displacement of the lesser trochanter of the left femur. When compared with the right side, the left femur shows obvious asymmetry, with separation and proximal displacement of the superior part of the lesser trochanter. Note that the growth plates of the greater trochanter remain unfused bilaterally, as would be expected in a 14 year old boy (fig 2).

Figure2

Fig 2 Radiograph of the hip showing separation and proximal displacement of the superior part of the lesser trochanter on the left side. The growth plates of the greater trochanter remain unfused bilaterally

2. What is the likely diagnosis?

Short answer

The most likely diagnosis is an avulsion fracture of the lesser trochanter.

Long answer

The most likely diagnosis is an avulsion fracture of the lesser trochanter. The separated bony insertion has been avulsed through a sudden forceful contraction of the iliopsoas muscle at the lesser trochanter of the femur in this skeletally immature athlete. This radiological diagnosis clearly fits with the history of sudden onset of pain in the groin and upper thigh during strenuous activity.

3. Who is most at risk of sustaining such an injury?

Short answer

Young athletes, aged 11-17 years are most at risk. The secondary ossification centres for the lesser trochanter of the femur appear at age 11 and fuse by age 17.1 During this period, any substantial traction force exerted by the inserting musculotendinous unit—the iliopsoas insertion to the lesser trochanter—may result in a bony avulsion injury.

Long answer

The types of injury seen in skeletally immature athletes, whose secondary ossification centres are unfused, differ from those commonly seen in the adult population—bony structures tend to be affected and muscles, tendons, and ligaments are relatively spared. Avulsion fractures are most common in the pelvis and lower extremities.2 The classic injury pattern in adolescents results from a sudden forceful contraction of the musculotendinous unit during sport—when kicking, running, or changing direction. Avulsion fracture of the lesser trochanter is rare.3 In a retrospective analysis of 1126 proximal paediatric femoral fractures only three children had an isolated avulsion fracture of the lesser trochanter.4 In one case series, only 11% of pelvic avulsion fractures involved the lesser trochanter.5

4. What is the standard management regimen for such an injury?

Short answer

Avulsion fractures of the lesser trochanter in adolescents are generally treated conservatively. Management aims to restrict the precipitating activity or event and offload the affected area, with partial weight bearing using crutches until symptoms resolve (usually one to two weeks).6

Long answer

Pelvic avulsion injuries in adolescent athletes are often mistaken for a simple muscle “strain.” In practice, imaging is usually undertaken only in patients who do not improve as expected or in those with functional limitation, such as inability to flex the hip or bear weight on the affected limb.

Patients with a suspected avulsion fracture of the lesser trochanter should therefore initially be investigated with a plain radiograph of the pelvis.7 8

The affected limb should be compared with the contralateral asymptomatic side to differentiate between a genuine avulsion fracture and an unfused apophysis.9 Plain radiography may provide false negative reassurance in people with a minimally displaced avulsion fracture. In these circumstances, when clinical suspicion is high, further investigation with ultrasound, computed tomography, or magnetic resonance imaging may help establish a diagnosis.9 Magnetic resonance imaging is particularly useful when assessing the degree of tendon retraction, and it can help the clinician make decisions about the need for early surgery.9

Avulsion fractures of the lesser trochanter in adolescents are generally treated conservatively with a five step rehabilitation regimen.5 Stage 1 aims to restrict any precipitating activity and offload the affected limb, with partial weight bearing using crutches, as well as cryotherapy and analgesia until symptoms resolve (usually one to two weeks).3 5 6

Once pain free, patients can progress to stage 2, where they can begin full weight bearing as tolerated and work on stretching to regain the full active and passive range of movement of the hip. Resistance training (stage 3) can begin when 75% of the range of motion is regained, with the aim of recovering full power of the injured limb.5 Stage 4, at one to two months after injury, aims to progress the stretching and strength training through sport specific exercises. Return to play follows a gradual progression from full weight bearing to low impact activity, such as deep water running, cycling, or cross-training. This progresses on to a run-walk programme and then a graduated increase in running speed, with the addition of cutting manoeuvres that require a rapid change in direction and sport specific drills.5 Stage 5 involves a full return to contact sport, with average healing times ranging from eight to 12 weeks in uncomplicated cases.10

5. What are the indications for surgical management of this injury?

Short answer

Surgery may be needed when there is a substantial degree of displacement of the avulsed fragment from the femoral origin. Proximal displacement of more than 2 cm would warrant an operative opinion.7 9 11

Long answer

McKinney and colleagues proposed a modification of the Martin and Pipkin classification system of apophyseal avulsion fractures that includes four grades of injury.3 12 A type 1 injury is a non-displaced avulsion fracture; type 2 describes an avulsion fracture with up to 2 cm displacement; type 3 is an avulsion fracture with more than 2 cm displacement; type 4 describes a symptomatic non-union or painful exostosis. Lesser trochanteric avulsion fractures are generally managed non-operatively, except for type 4 lesions, where the non-union or symptomatic exostosis can be excised and the muscle reattached to the insertion point.3 Type 3 avulsion fractures are treated on a case by case basis, with internal fixation considered if the bony avulsion fragment is large enough to enable fixation.

Surgical treatment may also be considered for patients with ongoing discomfort who cannot return to competitive sports after attempted conservative management.3 It is currently unclear whether surgical fixation results in a faster return to play than conservative management; however, internal fixation is often used in elite young athletes to facilitate a proposed rapid return to sport.3 No case series or case reports have documented surgical rates or operative outcomes for avulsion fractures of the lesser trochanter in adolescents.3 The medial surgical approach used for internal fixation of these fractures is complex and care must be taken to avoid damage to the obturator and femoral nerves, as well as the femoral vessels.

Patient outcome

Ten weeks after injury, extension, flexion, and adduction of the injured hip were comparable to the undamaged side and the boy could run without pain, although his endurance capacity was low. He has been advised not to play contact sport until 16 weeks after the injury, at which time he will undergo a repeat radiograph. If this shows radiographic evidence of union, this will reassure the clinician and patient, and enable the patient to return to full sporting activity.

Notes

Cite this as: BMJ 2014;348:g2766

Footnotes

  • Competing interests: We have read and understood the BMJ Group policy on declaration of interests and declare the following interests: None.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

  • Parental consent obtained.

References

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