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PROXIMAL HUMERUS FRACTURE WITH LOCKING PLATE: FUNCTIONAL AND RADIOGRAPHIC RESULTS

ABSTRACT Objective: To correlate the functional outcome and radiographic indices of proximal humerus fractures treated with locking plate. Methods: Seventy patients with proximal humerus fractures treated with locking plate, with mean follow-up of 30 months. These patients were analyzed for the score of the University of California, Los Angeles (UCLA) for the operated shoulder, range of motion measurements and radiography of both shoulders. After that, a graphical correlation was established between the radiographic measurements and the functional outcomes. Results: 78% good and excellent results according to the UCLA score, with mean130° elevation; 45° lateral rotation; and thumb-T10 medial rotation. The type of fracture according to the Neer classification and age had a significant correlation with the range of motion. An association was found between the lowest mean elevation and the UCLA score when the neck-shaft angle variation in the antero-posterior plane was greater than 15° varus (p <0.001). Conclusion: The variation of the neck-shaft angle measurement in the anteroposterior plane showed significant correlation with the range of motion and can be one of the predictors of functional results in proximal humerus fractures treated with locking plate. Level of evidence III, Retrospective Study.


INTRODUCTION
Proximal humeral fractures are relatively frequent; they account for 5-10% of all fractures. 1 Their incidence is 6.6 cases for every 1000 people every years 2 , 70% in patients above 60 years old. They are the second most common upper limb frac-ture and the third most common in patients above 75 years old. The most common mechanism of injury is fall from stand-ing protected by the extended hand. 3 Approximately 80% of these fractures have no displacement or are minimally displaced and sta-ble, resulting from low-energy trauma, and can be treated non-surgically 4 with good prognosis. Surgical treatment is reserved for patients with fractures that are displaced, unsta-ble, open, associated to vascular injury, or in polytrauma patients. According to the literature, there is no unique treatment method that is effective for all types of proximal humeral fractures. The most commonly used surgical techniques are: closed reduction and fixation with pins or percuta-neous screws, open reduction and internal fixation with plate and screws or with tension band, intramedullary nails, and hemiarthroplasty. 1,5 Internal fixation of the proximal humerus with locking anatomic plate favors the maintenance of the reduction obtained during surgery, allowing for earlier passive mobiliza-tion and thus facilitating post-operative rehabilitation. 6 However, this technique is not free from complication. The most common among them are: limitation of range of movement, avascular necrosis, loosening of the synthesis material, articular penetration of screws, and/or varus fixation of the humeral head. 7 This study aimed to evaluate the correlation between functional outcomes and radiographic indices of proximal humeral fractures treated with locking anatomical plate.

METHODS
This was a retrospective study conducted by the Shoulder and Elbow Group of the Orthopedics and Traumatology Service of the hospital, from february 2006 to May 2010, with 143 patients who suffered fracture of the proximal humerus and under-went surgical treatment (open reduction and internal fixation) with locking anatomic plate (PHILOS -Synthes ® ). The following patients were excluded: 5 patients with bilateral fractures; 6 individual for pre-senting infection (re-operated for removal of the synthesis material); 4 in which loss of fixation were replaced by hemiarthroplasty and 58 due to loss of follow-up. Of the 70 patients available for study, 44 fractured the right side and 26 on left side; 41 the dominant side and 29 the non-dominant; 50 were female and 20 male. The average age of patients was 67 years ranging from 21 to 92 years and the mean follow-up time was 30 months, ranging from 13 to 64 months. The most common mechanism of injury was fall from standing in 72% of de cases ( Table 1). The classification used in this study was described by Neer 8 in 1970, based on displacement of the four main frag-ments, which were firstly identified by Codman in 1934 9 : humeral head, greater tuberosity, lesser tuberosity, and diaphysis. According to Neer,8 multiple parts are considered when there are deviations greater than 1 cm or 45 o between frag-ments. For the greater tuberosity, a distance greater than 5 mm makes it a displaced part.
For diagnosis and preoperative classification, X-rays in the true shoulder anteroposterior, scapular Y, and Velpeau views were used, as well as CT scan when there was doubt regarding articular involvement. Of the 70 studied fractures, 20 were classified as two-part, 37 as three-part, and 13 as four-part. To assess the functional results, patients with a minimum of 12 months of follow-up were included. The degree of flexion and rotation (lateral and medial) of both shoulders was measured and the University of California in Los Angeles (UCLA) score was applied. Postoperative radiographic evaluation was standardized with a 100 cm distance from the X-ray apparatus to the film in the anteroposterior incidence (AP), with correction of anteversion of the glenoid cavity and limb in neutral rotation; scapular Y made with the patient standing in the posteroanterior posi-tion with 45 o anteriorly and the X-ray apparatus toward the scapula; and Velpeau view a modification of axillary profile for patients with upper limb immobilization. Radiographs were always made on the same day by the same previously trained staff, at least 18 months after surgery. The radiographic measurements assessed were the cervicodiaphyseal angle (formed by the intersection between a line perpendicular to the anatomical neck and a line parallel to the axis of the humeral diaphysis), compared to the non-operated side in true shoulder anteroposterior view 1 (Figure 1), and scapular Y(angle between a line passing through the anatomical neck and a line parallel to the diaphysis of proximal humerus (Figure 2), and distance between the proximal end of the plate and the apex of the greater tuberosity on the true shoulder anteroposterior view. The presence of pseudoarthrosis, avascular necrosis, and osteolysis was investigated. Subsequently, the correlation between changes in radio-graphic measurements and functional results was calculated. In the statistical analysis, the relationship between quantitative variables was chosen by Spearman's correlation. In studies of the variations we used the Kolmogorov-Smirnov test Lilliefors correction to verify the normality of the data. If it were not rejected the normality of the data was used the Student t test.

Functional results
For the 70 patients analyzed, the mean elevation of the operated limb was 130º (30º-170º), with a loss of 21% compared to the contralateral side (164º), the mean of external rotation (ER) was 45º with 30% reduction compared to the opposite side (64º) and the mean of internal rotation (IR) was thumb-T10, with its contralateral side mean was thumb-T7.
The worst scores of the study were in fractures classified as four-parts, four cases with excellent and good results (30.77%), four regular (30.77%) and five with poor results (38.46%).In the assessment of range of motion, the mean for elevation was 89º with a decrease of 45% compared to contralateral shoulder (162º). The external rotation loss was 28º with 45% reduction of motion (60º-32º). The average internal rotation-L1 was thumb with opposite side thumb-T9 (Table 2). Results statistically significant (p <0.05) when comparing the UCLA score and elevation, with age and number of parts of the Neer classification. The higher the age and the number of parts, the worst the flexion and UCLA score. (Figure 3 and 4).

Radiographic evaluation
In radiographic evaluation, five (7.14%) patients had avascular necrosis is therefore not possible to estimate the pre-established measures for the study (all classified as Neer fractures in 4 parts preoperatively). Of the 65 patients studied, the mean of cervicodiaphyseal the anteroposterior was: 131º on the operated side (82º -210º) and 138º the contralateral shoulder (126º-152º), the mean in the scapular Y view was 60º, and opposite side measuring 57º. The greatest differences were observed in four-parts fractures, specifically in the anteroposterior view that showed a difference of 17º compared to non-operated side ( Figure 5). When measuring the distance between the proximal end of the plate and the apex of the greater tuberosity, a mean of 6 mm (range: 0-1.6 mm) was obtained and in two cases is greater tuberosity of osteolysis.

Correlation between radiographic and functional outcomes
The worst functional outcomes were observed in cases where the difference between the operated and contralateral side was greater than or equal to 15 o varus in the anteroposte-rior incidence. In such cases, the patients had lower mean flexion (105,40º) and worse UCLA score (26,40). Patients who had variations lower than 15 o had mean flexion of 151º and mean UCLA score of 32,85. These results were statistically significant in the present study. (Figure 6) ( Table 3). For analysis of the distance between the proximal end of the plate and the apex of the greater tuberosity, patients were divided into two groups: the first, with values lower than 8 mm, and the second, with values greater than or equal to 8 mm. By comparing the results of bending between the two groups was not statistically significant (Table 4). We did not obtain statistically significant results, to correlate the radiographic measurements for scapular Y view with functional outcomes and UCLA.

DISCUSSION
In the present study, it was observed that deviations greater than 15 o varus relative to contralateral shoulder in anteropos-terior view are not well tolerated by the patient and lead to with flexion loss and a worse UCLA score. Solberg et al 10,11 reached a similar conclusion. In their study, the authors divided the results according to the obtained alignment relative to the contralateral shoulder. They considered less than 5 o of varus angulation of the humeral head as a good reduction. In turn, a satisfactory reduction ranged from 5 o and 20 o of varus deformity of the humeral head. The authors concluded that patients with good or satisfactory reductions had better outcomes than patients with varus deformity greater than 20 o , who presented flexion loss and worse functional outcome. Herbert Resch, 12 in a 2011 review article, also considered these parameters to be important, and proposed a classification based on varus and valgus deviations. Brunner et al 13 observed inferior results when the reduction of the fracture had cervicodiaphyseal angle with an increased varus; how-ever, their results were not statistically significant.
Although the surgical technique recommend that the distance of the plate relative to the greater tuberosity should be 8 mm and lower distances lead to a deficit of abduction and flexion due to impact of the plate on the acromion 14  In the present study, the higher the age of the patient and the number of parts of the fracture, the worst the flexion and the UCLA score. These results were statistically significant (p <0.003). Yang et al 18 found that the higher number of fracture parts and the lack of medial support (calcar comminution) were determiners of the functional outcome. Koukakis et al 19 also had worse outcomes related to age. In the present study, the cervicodiaphyseal angle was used as a comparative radiographic parameter with the contralateral shoulder for correlation with functional outcomes. However, there is no universal standardized method to measure this angle. Other biases in the results of this study which were not analyzed are the co-morbidities of patients, prior and late postoperative integrity of the rotator cuff, the extremes of the age. Further studies with greater emphasis on such factors are needed to complement the present findings.

CONCLUSION
This study indicates that the variation of the cervicodiaphyseal angle in the anteroposterior view was significant correlation with the range of motion. This radiographic parameter can be one of the predictors of functional results in fractures of the proximal humerus treated with locking plates.