Introduction

Trimalleolar fractures are severe ankle injuries, including fractures of the lateral, medial, and posterior malleoli.¹ These fractures are particularly prevalent in women between the ages of 75 and 84 years and make up around 7% of ankle fractures reported in orthopaedic units. Trimalleolar fractures must be properly managed to prevent them and guarantee the best possible functional results.

Malunion and nonunion are two of the most serious possible side effects of trimalleolar fractures.² Nonunion is the failure of the bones to heal fully, whereas malunion happens when the bones heal in an incorrect position.² A patient's quality of life may be severely impacted by these complications, which may result in long-term problems like arthritis, instability, and chronic discomfort.³

Malunion is more prevalent in non-surgically treated instances. Among the consequences, ankle instability, modified biomechanics, an increased chance of developing post-traumatic arthritis, long-term discomfort and pain.⁴ To restore joint congruity and lessen associated soft tissue damage, dislocated trimalleolar ankle fractures should be reduced immediately.^2,4 A chronic fracture site resulting from nonunion may cause persistent discomfort, instability in the ankle joint, restricted range of motion, and walking and weight-bearing difficulties.

Poor blood supply, insufficient immobilisation, and patient-related problems like smoking, diabetes, or advanced age are some of the causes that may lead to nonunion.⁵ It is crucial to treat trimalleolar fractures appropriately to reduce the chance of severe consequences. Since trimalleolar fractures are usually regarded as unstable and necessitate open reduction and internal fixation (ORIF), this usually entails surgical intervention.^1,,2

Understanding trimalleolar fractures

Three bony structures are vital for the ankle joint, as they offer support and permit movement. On the inside of the ankle, the lateral malleolus is the distal end of the fibula, the medial malleolus is a section of the tibia, and the posterior malleolus is the rear part of the distal tibia.^{1, 2} 

Trimalleolar fractures typically result from high-energy trauma such as car crashes, sports injuries, or falls from a height. Simple falls in older people, especially those 65 and older, can result in trimalleolar fractures, underscoring the ageing population's heightened susceptibility.

A precise diagnosis is necessary for appropriate treatment and problem avoidance. The main diagnostic method is X-ray imaging; however, because trimalleolar fractures are complex, sophisticated imaging methods are frequently required.⁶ CT scans give precise cross-sectional images that make it easier to see joint involvement and fracture patterns.

Because simple radiographs tend to underestimate posterior malleolus fractures, CT scans are beneficial in evaluating these injuries.⁷ Magnetic resonance imaging (MRI) may occasionally be used to assess soft tissue damage that coexists with fractures.⁸

Malunion of trimalleolar fractures

A series of clinical problems can result from malunion in trimalleolar fractures:

• Changed joint mechanics: Ankle joint surfaces that are not aligned correctly might interfere with normal biomechanics, causing an irregular distribution of load and more articular cartilage wear⁹
• Stiffness and chronic pain: Individuals who suffer from malunion frequently have limited ankle range of motion and chronic pain[¹⁰
• Post-traumatic arthritis: Early-onset osteoarthritis can result from post-traumatic arthritis because of the altered joint mechanics and increased stress on the articular surfaces, which can hasten cartilage deterioration¹¹
• Abnormalities in gait: Modifications in the alignment and function of the ankle joint may lead to different walking patterns, which may result in subsequent problems with other lower extremity joints¹²

Surgery is frequently necessary to address malunion in trimalleolar fractures to rectify the deformity and restore appropriate joint alignment. The following are the main available treatment options:

• Corrective osteotomy: To restore appropriate anatomical alignment, the malunited bone is surgically sliced and realigned. The particular method employed is contingent upon the type and location of the malunion²
• Joint realignment techniques: More involved operations can be required to realign the joint surfaces and restore appropriate biomechanics in situations when the malunion has resulted in a substantial amount of joint incongruity¹³
• Physical therapy for recovery: After surgery, a thorough rehabilitation program is essential to regaining the injured ankle's strength, flexibility, and functionality² 

The degree of the deformity, the patient's symptoms, and their health all play a role in deciding the correct surgical procedure for malunion. Conservative care with bracing, orthotics, and physical therapy may be preferable to surgical intervention in certain situations, especially in elderly persons or those with major comorbidities.¹⁴

Nonunion of trimalleolar fractures

The inability of bone healing to occur within the anticipated time range, i.e., 6–9 months following damage, is known as nonunion. This condition impacts patients' quality of life and functional outcomes.¹⁵ When it comes to trimalleolar fractures, nonunion can take two primary forms:

• Excessive bone growth without bridging across the fracture site is known as hypertrophic nonunion.¹⁵ This kind is frequently linked to insufficient stability throughout the healing process
• Atrophic nonunion, which  is characterised by a lack of bone growth, is usually brought on by poor biological variables like infection or a compromised blood supply

Nonunion in trimalleolar fractures is caused by several reasons. One of the main concerns is inadequate blood flow to the fracture site, especially when there is significant soft tissue damage or vascular compromise.¹⁶ Infection can seriously hinder recovery, particularly in open fractures or after surgery. By interfering with the delicate healing process, inadequate immobilisation or early weight-bearing can potentially result in nonunion. Many patient-related factors influence this development.¹⁷ 

Diseases like diabetes hamper bone repair, which alters microvascular circulation.¹⁸ Studies have demonstrated that smoking reduces bone healing and raises the incidence of nonunion, making it a known risk factor. Other reasons that might lead to nonunion include advanced age, severe anaemia, and low nutritional status.¹⁷ Ankle joint instability is prevalent, which reduces movement and raises the risk of falls. Patients are also more susceptible to additional fractures or injuries due to the ankle's reduced structural integrity.¹⁹

Surgery is usually necessary to treat nonunion in trimalleolar fractures. A popular method is bone grafting, which uses autografts (from the patient's own body) or allografts to promote the growth of new bone.²⁰ Fixation revision may be required in situations of hypertrophic nonunion to improve stability. Stable fixation and bone grafts are frequently needed for atrophic nonunions.²⁰

The promotion of bone repair may benefit from adjunctive therapy. Bone stimulators that use low-intensity pulsed ultrasound or electromagnetic fields have demonstrated potential in speeding up bone growth and raising union rates.²¹ Patients with impaired capacity for healing may benefit most from these non-invasive therapies.

Effective management of underlying problems is essential for nonunion therapy. Healing potential can be greatly increased by quitting smoking, improving nutritional status, and optimising glycemic management in diabetes patients.²² Before trying final fixation, intensive therapy with the right medicines and, if required, surgical debridement is crucial in cases where infection is present.²³

Prevention of malunion and nonunion

Although surgery is frequently required for the best results, problems like malunion and nonunion can still arise and cause serious functional impairment as well as long-term effects. To ensure the best potential outcomes for patients, it is imperative to prevent these problems. Preventing malunion and nonunion requires careful surgical technique and fixation. 

For trimalleolar fractures, ORIF (Open Reduction and Internal Fixation) is typically the recommended course of treatment since it enables stable fixation and anatomic reduction.² To better diagnose fracture patterns and plan suitable fixation procedures, preoperative planning has increasingly relied on the use of modern imaging techniques, CT.²

Direct fixation has been more popular for the posterior malleolus in recent years. Directly repairing the posterior malleolus fragment has been demonstrated to improve clinical results and reduction quality.² Additionally, this method can lessen the requirement for trans-syndesmotic fixation and prevent syndesmotic diastasis, which promotes more stable healing and may lower the likelihood of malunion.²

Preventing complications requires proper post-operative care. Current research indicates that early mobilisation and weight-bearing may produce better results than protracted immobilisation, which was a common practice in traditional therapy.²⁴ Early post-operative pain-dependent weight-bearing and mobilisation increased range of motion, accelerated return to work, and improved short-term functional scores, according to a study.²⁴

Another crucial component of preventing malunion and nonunion is educating patients about lifestyle changes. Given that smoking has been demonstrated to impede bone healing and raise the chance of nonunion, quitting is very crucial.²⁵ It's also critical to manage comorbidities like diabetes, which can impact microvascular circulation and hinder bone repair.²⁵ 

Close monitoring is crucial when conservative therapy is selected, especially in older persons or those with serious comorbidities. Conservative therapy produced good results in a randomised controlled trial comparing close contact casting with surgery for unstable ankle fractures in older adults.² But because of the lack of fracture reduction, 19% of patients required conversion to internal fixation, and this method necessitated routine radiographs to check joint congruency.²

Summary

Malunion and nonunion are two of the most difficult ankle injuries that can result from trimalleolar fractures, which are complicated injuries that can cause serious problems. Nonunion is the inability of bone to heal within the anticipated time frame, whereas malunion happens when a fracture repairs in an incorrect location, resulting in joint incongruity and changed biomechanics. Both issues can have a major negative influence on patients' quality of life by causing instability, persistent discomfort, and decreased mobility.

Regular radiography monitoring is necessary for early detection and intervention, particularly when conservative therapy is used. Preventing these issues requires appropriate initial management, which usually entails ORIF. Direct fixation of the posterior malleolus and increased interest in arthroscopic-assisted ORIF for younger patients are recent therapeutic trends. 

Evaluating the long-term advantages of direct posterior malleolus fixation in younger individuals and defining indications for various treatment modalities in senior patients with osteoporotic fractures should be the main goals of future studies. Research into new treatment approaches and rehabilitation techniques will be essential as our knowledge of these complicated injuries develops to reduce the likelihood of malunion and nonunion and, eventually, enhance the long-term results for patients who suffer from trimalleolar fractures.