Fracture, Posterior Malleolus

By admin On Sep 29, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Steven G. Reece

Basics

Description

Ankle fracture involving the posterior malleolus
Isolated posterior malleolus fractures result from vertical loading or anterior displacement of the tibia when the foot is planted.

Epidemiology

Isolated posterior malleolus fractures are very uncommon.
∼1% of all ankle fractures

Risk Factors

Osteoporosis
Repetitive vertical loading

Etiology

Abduction or external rotation, posterior displacement of the talus, vertical loading, or combinations of these forces, cause fractures of the posterior malleolus.

Commonly Associated Conditions

Associated soft tissue ankle injuries (lateral, deltoid, and syndesmotic injuries)
Bimalleolar or trimalleolar (posterior malleolus fractures in conjunction with lateral malleolus fractures, medial malleolus fractures, or both)
Fracture patterns can be suggestive of posterior malleolar involvement:
- Tibial spiral fractures often associated with occult posterior malleolar involvement; use CT scan to evaluate

Diagnosis

Diagnosis of posterior malleolar fractures hinges on high degree of suspicion in the right acute or chronic clinical setting.

History

Very important to obtain exact mechanism of injury:
- Posterior malleolus fracture has been described in association with external rotation-abduction injuries (1).
History should address chronic vs acute.

Physical Exam

Consider a fracture if patient is unable to bear weight or has significant swelling or ecchymosis in acute setting.
Chronic presentation: “Sprain” that persists in being painful but is not unstable
Observe for obvious deformity, ecchymosis, and swelling.
Palpate for pain, starting away from area of maximal tenderness, and compare to uninvolved foot.
Check for ligamentous laxity.
Assess neurovascular status.
Assess ability to bear weight and gait.

Diagnostic Tests & Interpretation

Imaging

X-rays needed to confirm diagnosis 2:

Anteroposterior (AP), lateral, and mortise views should be obtained.
Use of stress views remains controversial because there are no standard techniques for anesthesia, positioning, or force used to elicit instability.
External-rotation lateral view of the ankle often helpful
CT and MRI sometimes used to evaluate complex ankle fractures:
- CT recommended if high clinical suspicion and negative plain films (3)

Differential Diagnosis

Acute setting:
- High-grade ankle sprain
- Lateral/medial malleolus fractures
- Achilles' tendon injury
- Peroneal tendon subluxation and dislocation
Chronic setting:
- Os trigonum syndrome
- Retrocalcaneal bursitis

Treatment

Posterior splint with compression wrap
Ice, elevation
Crutches and make nonweight-bearing
Opioid analgesics vs NSAIDs (4):
- NSAIDs use with fractures in question
Follow-up in 1 wk if no emergent surgical indications present
If >25% of the articular surface is involved, or if the fracture is displaced >2 mm, then open reduction internal fixation (ORIF) is recommended.
If ORIF is not chosen, closed reduction still is needed
Oblique plain films postreduction, in addition to AP, lateral, and mortise views
CT scan may be indicated.
Nonweight-bearing posterior splint for 1 wk:
- Cast for total of 6 wks if fracture nondisplaced
- If fracture is displaced, then surgical repair (ORIF)

Medication

Opioid use vs NSAIDs (4):

Use of NSAIDs recently brought into question in fracture care pain management
NSAIDs shown to potentially negatively affect fracture repair

P.239

Additional Treatment

Additional Therapies

Physical therapy after both operative and nonoperative care:

Regain full range of motion, strength, and proprioception

Surgery/Other Procedures

If >25% of the articular surface is involved, or if the fracture is displaced >2 mm, then ORIF is recommended.
When associated with syndesmosis injury, fixation of posterior malleolus may be preferred over syndesmotic screw (5).

Ongoing Care

Follow-Up Recommendations

Orthopedic referral should be considered for any isolated fractures of the posterior malleolus because they often are complicated by other injuries.

Patient Education

It is important to discuss that ankle sprains and fractures often are difficult to differentiate.
If diagnosed ankle sprain, persistent symptoms (pain, swelling, limp) warrants follow-up and further workup
Many different outcomes exist, depending on the severity and type of ankle fracture: Compliance is critical.

Prognosis

Isolated posterior malleolar fractures have an excellent prognosis.
Those posterior malleolar fractures associated with significant comorbid fractures and/or syndesmotic injuries are much more likely to have long-term issues:
- Post-traumatic arthritis
- Loss of normal range of motion

Complications

See “Prognosis.”

References

1. Clanton TO, Porter DA. Primary care of foot and ankle injuries in the athlete. Clin Sports Med. 1997;16:435–466.

2. Leddy JJ, Smolinski RJ, Lawrence J, et al. Prospective evaluation of the Ottawa Ankle Rules in a university sports medicine center. With a modification to increase specificity for identifying malleolar fractures. Am J Sports Med. 1998;26:158–165.

3. Boraiah S, Gardner MJ, Helfet DL, et al. High association of posterior malleolus fractures with spiral distal tibial fractures. Clin Orthop Relat Res. 2008.

4. Harder AT, An YH. The mechanisms of the inhibitory effects of nonsteroidal anti-inflammatory drugs on bone healing: a concise review. J Clin Pharmacol. 2003;43:807–815.

5. Gardner MJ, Brodsky A, Briggs SM, et al. Fixation of posterior malleolar fractures provides greater syndesmotic stability. Clin Orthop Relat Res. 2006;447:165–171.

Additional Reading

Prokuski LJ, Saltzman CL. Challenging fractures of the foot and ankle. Radiol Clin North Am. 1997;35:655–670.

Wedmore IS, Charette J. Emergency department evaluation and treatment of ankle and foot injuries. Emerg Med Clin North Am. 2000;18:85–113, vi.

Codes

ICD9

824.4 Bimalleolar fracture, closed
824.6 Trimalleolar fracture, closed
824.8 Unspecified fracture of ankle, closed

Clinical Pearls

Posterior malleolar fractures rarely occur in isolation, so a high index of suspicion is necessary when lateral or medial malleolar fractures and/or syndesmotic injuries are diagnosed.
An undiagnosed posterior malleolus fracture can be the source of chronic pain in the setting of ongoing pain associated with an ankle “sprain.”
Apply the Ottawa rules coupled with a few additional tips to catch these on x-ray. If not seen on x-ray, consider CT scan.
ORIF if >25% articular surface or >2 mm displacement; otherwise, nonoperative options are appropriate.