WHICH FACTORS CAN DEFINE THE PROGNOSIS OF ARTICULAR FRACTURES OF THE CAPITELLUM AND TROCHLEA?

ABSTRACT

Introduction:

Articular fractures of the distal humerus involving the capitellum and trochlea (AO 13B3) are complex and challenging to manage without consensus in the literature on the most appropriate management.

Objective:

Evaluate radiographic features and treatment-related factors that may be positively or negatively correlated with the outcome of these fractures.

Methods:

Sixteen adult patients who underwent surgery between 2007 and 2024 with at least one year of follow-up were analyzed retrospectively. Radiographic characteristics, postoperative range of motion, and complications were evaluated. Statistical analysis used Odds Ratio (OR) and Fisher's Exact Test.

Results:

Elbow stiffness occurred in 56% of patients, 83% of which were in cases with posterior wall involvement (OR=7.5; p=0.08). Preoperative immobilization for more than seven days was associated with range of motion impairment (60%, OR=3; p=0.58) and ulnar nerve neuropathy (30%, OR=6; p=0.09). All cases of ulnar neuropathy occurred in women with prolonged immobilization (OR=8.08; p=0.09).

Conclusion:

Posterior wall integrity is a relevant prognostic factor for the final range of motion. The propensity for ulnar neuropathy in women and those with prolonged immobilization, although without statistical significance, suggests the need for larger samples. Level of Evidence II; Retrospective study.

INTRODUCTION

The distal humerus is divided into two columns, medial and lateral, which are extra-articular and articular, respectively. In its articular segment, it is formed by a "tie arch" connecting the distal end of the lateral column, composed by the capitellum; and in the most medial part, between the medial epicondyle and the capitellum, the trochlea (Figure 1). ^1–3

Figure 1. Column structure of the distal humerus – anterior view.

Source: Author's own work.

The capitellum and trochlea are irrigated by perforating condylar vessels that are branches of the recurrent radial, radial collateral, and recurrent interosseous arteries (Figure 2), which maintain an intimate relationship with the posterior wall of the distal end of the humerus, that may potentially suffer devascularization in fractures involving this region. ^4–7

Figure 2. Extraosseous vascular anatomy – anterior view.

Source: Author's own work.

Fractures of the distal humerus, involving the capitellum and trochlea, may occur isolated or combined. Isolated capitellum fractures represent 1% of elbow fractures and 3% to 6% of distal humerus fractures. Isolated trochlea fractures are rare.

Females are the most affected by this type of fracture, and this greater predisposition might be related to osteoporosis, cubitus valgus and elbow recurvatum. ^5,10,11

Several classifications for this type of fracture can be used. Anatomically, the AO classification divides them into extra-articular (13A), partially articular (13B), and complete articular (13C). In the present study, we will only use partially articular fractures in the coronal plane (13B3) and their respective subdivisions: capitellum fracture (13B3.1), trochlea fracture (13B3.2), and fracture of both (13B3.3). ¹² In addition, we also have the Dubberley et al. classification, which is divided into: fracture of the capitellum with or without involvement the lateral trochlear ridge (type I); fracture of the capitellum and trochlea as a single piece (type II); fractures of both the capitellum and trochlea as separate fragments (type III). In this classification, they are subdivided according to posterior wall comminution: no posterior comminution (subtype A) and posterior comminution (subtype B).

There are several possibilities for surgical treatment, including open reduction and internal fixation, closed reduction, fragment excision, and arthroscopic reduction. However, there is no consensus regarding the most appropriate treatment, since distal intra-articular elbow fractures are difficult to manage both clinically and surgically with unpredictable outcomes.

We will retrospectively evaluate possible radiographic factors that correlate better and worse outcomes in operated patients. Among these factors analyzed, the integrity of the posterior wall and both isolated or combined involvement of the capitellum and trochlea. We also evaluated the time to procedure and preoperative immobilization time.

METHODOLOGY

Our work was approved by the ethics and research committee under code CAAE 78440024.2.0000.5479.

Our study consists of a retrospective and descriptive analysis based on the review of medical records of consecutive patients who suffered articular fractures of the distal humerus and underwent procedure by the Trauma Surgery Group of the Department of Orthopedics and Traumatology of Santa Casa de São Paulo from January 2007 to January 2024 with at least one year of follow-up.

The Inclusion criteria were adult patients of both genders with elbow fractures classified as AO 13B3. Patients with pathological bone fractures, incomplete radiographic data, or incomplete medical records were excluded from the study, as were those who did not agree to participate in the study.

Radiographic characteristics of the fracture were analyzed, such as posterior wall involvement, presence of isolated or combined fractures of the capitellum and trochlea, as well as other associated fractures. In addition, patient follow-up included evaluation of postoperative range of motion and complications presented by the patients.

For statistical analysis, the Odds Ratio (OR) was calculated, and Fisher's Exact Test was used to calculate the 95% significance level (p<0.05).

RESULTS

From 2007 to 2024, 16 patients with fractures classified as AO 13B3 were operated. Regarding the Dubberley et al. classification, eight patients were classified as type I (two of whom were subtype IB), four patients as type II (two were subtype IIB), and four as type III (two were subtype IIIB).

The average age of the patients was 44 years (26 to 75 years), with nine female patients. In all cases, a capitellum fracture was found, and in eight of these, a trochlea fracture was associated. Other associated fractures included: radial head (three patients), coronoid process (one patient), and medial and lateral condyle of the elbow (one patient), as shown in Table 1.

Table 1. epidemiological data of patients with AO 13B3 fracture.

Gender	Age at trauma (years)	Posterior Wall Integrity	Dubberley	Associated Fractures	Fl.	Ext.	Pr.	Sup.	Complications
F	39	yes	IA	N	110°	-40°	80°	80°	N
M	26	yes	IA	N	110°	-5°	90°	90°	N
M	28	yes	IA	N	140°	0°	80°	90°	N
F	52	no	IIIB	N	140°	-20°	90°	70°	SMR
M	31	no	IIB	radial head	120°	-30°	80°	90°	N
F	58	no	IIIB	N	130°	-45°	80°	70°	Ulnar n. paresthesia
F	33	yes	IIA	N	90°	-20°	50°	20°	Ulnar n. paresthesia
F	55	yes	IIA	N	130°	-30°	70°	70°	N
M	27	no	IB	N	80°	-10°	90°	90°	SMR and infection
M	36	yes	IA	coronoid process and radial head	130°	-10°	90°	80°	N
M	31	yes	IA	radial head	125°	0°	90°	90°	N
M	75	no	IB	lateral and medial condyle	100°	-20°	90°	90°	N
F	53	no	IIIB	N	130°	-40°	80°	70°	Ulnar n. paresthesia
F	62	yes	IA	N	130°	-40°	70°	40°	N
F	38	yes	IIIA	N	140°	-25°	80°	80°	N
F	66	yes	IIA	N	130°	-20°	70°	80°	N

Source: SAME Medical Records Data - Santa Casa de São Paulo. Legend: M=male, F=female, N=none, SMR = synthesis material removal, ulnar n.=ulnar nerve, Fl.=flexion, Ext.=extension, Pr.=pronation, Sup.=supination.

At the end of follow-up, patients presented an average range of motion of flexion 123° ± 20°, extension −25° ± 16°, pronation 80° ±11°, supination 75° ± 20°. We noted that 56% of operated patients developed elbow stiffness, and evaluating only cases where the posterior wall was compromised, this number rose to 83% (OR= 7.5; p = 0.08).

Among patients who had a preoperative immobilization of more than seven days, 60% developed a restricted range of motion (OR= 3; p = 0.58) and 30% suffered from ulnar nerve neuropathy (OR 6; p = 0.09) (Figure 3).

Figure 3. Patient No. 15 with seven months of postoperative follow-up.

Source: Authors' image file.

During follow-up, five patients (31%) presented major complications requiring reoperation: one patient needed synthesis material removal (SMR) to gain range of motion, one patient needed SMR due to infection, and three patients had postoperative ulnar nerve paresthesia (Figure 4).

Figure 4. Computed tomography images demonstrating a fracture with preservation of the posterior wall integrity (A) and with posterior wall involvement (B), respectively.

Source: SAME – Santa Casa de São Paulo tomographic archives.

DICUSSION

Patients with combined capitellum and trochlea fractures (Dubberley type II and III) did not show a worse functional prognosis when compared to those with isolated capitellum fractures (Dubberley type I). This fact surprised us, given that the articular surface was compromised in both the medial and lateral columns, and including the trochlea, which truly serves as a guide for flexion and extension. This highlights a greater importance of the ulnohumeral joint in this movement, and not only in pronation and supination (Figure 5).

Figure 5. Radiographic images showing isolated capitellum fracture (A) and associated capitellum and trochlea fracture (B), respectively.

Source: SAME – Santa Casa de São Paulo radiographic archives.

Hildebrand et al. ¹³ proposed that due to hypertrophy of the anterior portion of the joint related to a greater distribution of myofibroblasts in this region, extension, when compared to flexion, would be the most compromised movement. However, in our study, flexion was the most significant alteration in the range of motion. Among the evaluated patients, 67% demonstrated restriction to flexion, whereas none of the evaluated patients developed restriction to pronation.

The relationship between preoperative posterior wall integrity and a worse final range of motion in patients exists and may be related to the blood supply of the capitellum and trochlea, which arises from perforating vessels of the posterior condyle, potentially associated with partial devascularization and non-union. ⁴ We also considered the importance of fixation in at least two planes was necessary in these situations, as a smaller anterior-to-posterior fixation as well as the other way around would not stabilize this fracture sufficiently (Figure 6).

Figure 6. Radiographic images showing fracture fixed in two planes (A) and fracture fixed in only one plane (B), respectively.

Source: SAME – Santa Casa de São Paulo radiographic archives.

During follow-up, the most frequent complication was elbow stiffness, followed by ulnar nerve neuropathy.

An association of ulnar nerve neuropathy with males has been described in the literature due to the presence of anatomical changes, such as a larger coronoid process, thicker cubital tunnel retinaculum, and lack of adipose tissue around the cubital tunnel, making them more susceptible to nerve compression. ¹⁴ Despite this, all patients in our study who developed this complication were females (OR= 8.08; p = 0.09). Immobilization time until the procedure with the elbow flexed at 90° was a risk factor for developing this type of complication, corroborating the relationship previously described in the literature, and all patients who developed ulnar neuropathy had prolonged immobilization time. ¹⁴

Prolonged preoperative immobilization also showed a significant correlation with the recovery of range of motion during the postoperative period, demonstrating and proving the importance of early mobilization, including immediate postoperative passive movement, aiding in the drainage of articular and periarticular fluids.

We cite here the absence of data regarding postoperative immobilization time in some patients as a limiting factor of the study, as it was not possible to establish any relationship with this fact.

Among the patients who underwent olecranon osteotomy during surgical approach, 60% of them developed elbow stiffness (OR= 1.25; p = 1).

CONCLUSION

Our study demonstrated that, although combined capitellum and trochlea fractures did not present a worse functional prognosis when compared to isolated capitellum fractures, posterior wall integrity proved to be a significant factor in the final range of motion.

It was also possible to observe, despite the absence of statistical significance, a greater tendency for the occurrence of ulnar nerve neuropathy in women. Likewise, a propensity for ulnar nerve neuropathy in patients with prolonged immobilization time, despite the absence of statistical significance. However, both could be confirmed with larger samples.

DATA AVAILABILITY DECLARATION

The data underlying this study are contained within the manuscript.