1 Introduction

Capitellum fractures are rare, constituting only around 1% of all elbow fractures.¹ These fractures are intra-articular and classified as per the system given by Bryan and Morrey, modified by McKee et al.^2,3 Type IV fractures are coronal shear fractures of the capitellum and may also include the trochlea. The fractured fragment does not have any soft tissue attachments and usually translates anteriorly and proximally. These types of fractures are usually treated by open reduction and internal fixation with the help of headless compression screws. However, when neglected or mismanaged, these fractures are prone to malunion or non-union and cause a bony block to flexion and elbow pain coupled with post-traumatic arthrosis of the elbow. Capitellum malunion has been historically managed with fragment excision or radio capitellar arthroplasty once post-traumatic arthritis has set in Ref. ⁴ Excision of capitellar fragment carries the risk of subsequent posterolateral instability of the elbow. Evidence on the management of capitellar malunion is limited. In our knowledge, there are only two prior case reports on the management of capitellar malunion, and both describe corrective osteotomy and fixation in type I (Hahn Steinthal) fractures.^5,6 Thus, we present a novel treatment strategy for managing the malunion of type IV capitellum fracture.

2 Case presentation

A 23 years old woman presented with a history of a motor vehicle accident, followed by pain and swelling of the right elbow eight months ago. She was examined at a nearby hospital and given an above-elbow slab for four weeks. After removing the slab, the patient continued to experience pain and restriction of movement. On follow-up consultation at the local centre, she was advised to exercise and reassured of gradual improvement; she presented to us seven months later due to worsening pain and stiffness in the right elbow.

On local examination, tenderness was elicited over the distal humerus and elbow range of motion was restricted (70⁰ to 90⁰), with pronation of 30° and supination of 0°. There were no distal neurovascular deficits.

On investigation, radiographs revealed a malunited Type 4 capitellum fracture, wherein the capitellar fragment had translated proximally and united with the anterior aspect of the distal humerus (Fig. 1). Computed tomography of the elbow confirmed the same and also showed that the fragment also consisted of a coronally split portion of the lateral flange of the trochlea (AO type B3.3).

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Fig. 1 Pre-op x-ray of the elbow showing malunited capitellum fragment.

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3 Treatment

Open reduction and fixation with headless compression screws were planned after discussing the options of excision, osteotomy and fixation and radio-capitellar arthroplasty with the patient. The risks of early post-traumatic arthritis, capitellum osteonecrosis, heterotopic ossification, elbow instability and stiffness were explained to her and informed consent was obtained.

The patient was placed in a lateral decubitus position with her arm supported by a post and a sterile tourniquet was applied. The arm was prepared and draped keeping the distal arm and forearm free. A midline posterior incision was given and a chevron osteotomy of the olecranon was performed. The lateral collateral ligament with common extensor origin was elevated off the lateral condyle to fully expose the distal humeral articular surface (Fig. 2). An osteotomy of the malunited fragment was performed with a thin osteotome and fracture margins were freshened and curetted. First, the trochlear fragment was reduced and temporarily fixed with a k wire after which the capitellum was reduced and stabilised (Fig. 3). After ensuring a satisfactory reduction, both the fragments were fixed with 3.2mm headless screws (depuy, synthes) in an anteroposterior manner. Marked cartilage thinning was noted over the fracture fragments, and we were doubtful about the cartilage integrity. Hence, the decision of interposition of fascia was taken. Tensor fascia-lata graft of appropriate size was harvested from the ipsilateral thigh and fixed over the distal humerus (Fig. 4). Lateral collateral ligament and common extensor muscle were reattached to lateral condyle with No.2 non-absorbable sutures and olecranon was fixed with tension band wiring with a 4.5 mm partially threaded cannulated screw. The closure was done in layers over a surgical drain. An above-elbow slab was applied post-operatively.

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Fig. 2 The intra-op image of distal humerus showing osteotomy of malunited capitellum and fixation with k wires.

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Fig. 3 Intra-op image of the distal humerus showing osteotomy of malunited capitellum and fixation with k wires.

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Fig. 4 Intra-op image of elbow showing interposition arthroplasty using tensor fascia lata graft.

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The drain was removed on postoperative day two. Active elbow movements were started after one week postoperatively and the slab was removed, and the patient was put on a hinged elbow brace. Gradually, active-assisted elbow exercises were started, followed by passive exercises at the end of six weeks. Three months post-surgery radiological union was achieved (Fig. 5). However, the patient started to have hardware irritation at the elbow due to the tension band wire. It was removed one -year post-surgery (Fig. 6). At the final follow-up at 18 months; the patient was found to have active painless elbow flexion from 15 to 90° (Fig. 7). Though the functional arc of elbow ROM was achieved intra-operatively, ROM achieved in final follow-up was from 15-90°, little less than functional arc of elbow motion. However, patient was happy with the achieved ROM and was able to do most of the daily activities without difficulties. Radiologically, there was slight flattening and sclerosis of the capitulum with some signs of arthrosis (Fig. 8). However, the patient did not have any pain. She had an excellent Mayo Elbow Performance score of 95. She was satisfied and had resumed her routine activities of daily living.

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Fig. 5 Post-op x-ray of the elbow at 3 months showing radiological union of capitellum fragment.

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Fig. 6 Post-op x-ray of the elbow at 1 year after tension band wire hardware removal.

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Fig. 7 Post operative image of the patient at final follow-up of 18 months showing final elbow ROM achieved.

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Fig. 8 Post-op x-ray of the elbow at final follow–up of 18 months.

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4 Discussion

Capitellum fractures are rare and difficult to manage due to their small size, precarious vascularity, and intra-articular nature.⁷ Brian and Morrev had initially classified capitellum fractures into three types-type I (the Hahn-Steinthal fracture), isolated fractures of the capitellum and subchondral bone; type II (the Kocher-Lorenz fracture), isolated fractures of only the articular cartilage rim of the capitellum; and type III, capitellum fractures with any comminution or articular compression.² McKee et al. modified this to include type IV, a capitellum fracture due to coronal shear with extension medially into the trochlea.⁷ Acute fractures are usually managed by open reduction and internal fixation using plates or headless screws, small fragments are excised.¹ Various methods of fixation like threaded k-wires, headless compression screws and absorbable implants have been used for capitellum fractures. Anterior to posterior screw fixation is preferred as it is said to be more biomechanically stable and preserves the blood supply of the capitellum which is derived from the posterior soft tissues.^7,8

Capitellum fractures may be missed on plain radiographs and computed tomography is essential whenever there is a suspicion of capitellar fractures. When missed these injuries are prone to undergo non-union or malunion. There is limited experience and evidence for these sequelae of capitellar fractures. Bilic’ et al. reported a malunion of Type 1 capitellum fracture in an 11-year-old child who presented three and half months post-injury and was treated with corrective osteotomy and fixation with 3 bioabsorbable screws.⁵ Jeevannavar et al. reported a malunion of Type 1 capitellum fracture in a 20 years old female managed with corrective osteotomy and 2 herbert screws.⁶ Both reported good outcomes, with a stable, functional and painless elbow at the end of follow-up. Yejun et al. presented a series of 6 cases of missed capitellum fractures that had a good functional outcome at follow-up after undergoing corrective osteotomy and internal fixation.⁹ Some authors recommend excision of the capitellar fragment, which however comes at the cost of elbow stability.⁷ Radio-capitellar arthroplasty has also been performed by a few authors once post-traumatic arthrosis has occurred.⁴

We propose fascia lata interposition arthroplasty may be added, in addition to corrective osteotomy and internal fixation in case of doubtful integrity of articular cartilage intraoperatively in patients undergoing delayed surgery to address the post-traumatic arthrosis and to achieve a painless range of motion. Interposition arthroplasty with or without a hinged external fixator, depending on the elbow stability is an excellent option in young patients with no significant bone defect as it offers a painless, functional arc of motion with little compromise on stability.¹⁰ It is a suitable treatment strategy for young patients who may not accept elbow arthrodesis and are unsuitable for prosthetic replacement. Interposition arthroplasty can act as a bridge to radio capitellar or total elbow arthroplasty in young patients. This needs consideration, especially in capitellum fractures with thinned articular cartilage or compromised articular cartilage, occurring in adolescents and young adults.

5 Conclusion

Capitellum fractures are rare and need a high index of suspicion. They are best visualized on computed tomography images. Malunion of capitellum fractures can be successfully treated with a corrective osteotomy and anterior to posterior screw fixation. In cases with delayed presentation and thinned cartilage intraoperatively, interposition arthroplasty may be added to delay post-traumatic arthrosis, reduce pain and act as a bridge to future arthroplasty for young patients. Our follow-up was till 18 months. However, longer follow-up is needed to watch for capitellar osteonecrosis and post-traumatic arthritis. Also, study with a larger sample size and comparison group is needed to validate our results of a single case.

Declaration of patient consent

The authors certify they have obtained all appropriate patient consent forms. In the form, the patient has given their consent for patient images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Authors contribution

1st authors examined, followed up on the case and contributed to writing the case report. The 2nd author operated the case, the 3rd author helped in the follow-up of the case and helped in writing the case report, and the 4th and 5th authors critically appraised the manuscript.

Conflict of interest and financial disclosure

None.

Source of support

None.

Ethics

This study was conducted in accordance with the guidelines set up by ICMR (2017) and Helsinki declaration (modified 2013), after the approval of the Institute Ethics Committee (Ref: IEC/INT/2022/Study-436).