Efficacy of Reverse Triangle Screw Fixation in Patients Suffering from Femoral Neck Fractures

MATERIALS AND METHODS

Methods: In this cohort study, 60 patients with mean age of 49.12±16.8 with femoral neck fracture appointed for reverse triangle fixation participated from April 2008 to April 2011 in orthopedic department of Tabriz Shohada Hospital for a 36 month period. Nine patients were excluded due to abnormal reduction. Finally, the left 51 patients were divided into two perfect (34 patients) and imperfect (17 patient) groups considering surgeon comment on position of screws after fixation. The results were compared in two groups during one year follow-up. The present study has been confirmed by ethical committee of Tabriz university of medical sciences. Study exclusion criteria include patients suffering from osteoporosis, those suffering from diabetes mellitus, patients with major trauma, those who are younger than 18 years old and patients who cannot be followed up. There were 51 patients suffering from one-sided femoral neck fracture treated by reverse triangle screw fixation entered the study through frequent sampling and using simple method. After surgery, Anterior Posterior (AP) and lateral graphs of the operated area were analyzed by 3 orthopedic specialists. They reported the screw positions as perfect and imperfect. If there were at least two similar reports, they will be regarded as the patient's condition by the orthopedist. It should be mentioned that these three orthopedists were not aware of each other’s comments and none of them was the related surgeon. After surgery, the patients were visited at 1, 3, 6 and 12 month intervals. After reduction, the fractured area was fixed using three 6.5 mm cancellous screws such that two screws was placed in proximal section at a 0.5 cm distance of anterior and posterior of subchondral bone. Another screw was centrally placed at distal section. These three screws are placed divergently. Concurrent existence of four following radiological conditions means perfectness of screw position:

Lack of each of the above-mentioned conditions places the patient at imperfect group. The studied factors included age, gender, damage mechanism, damage to surgery interval, type of fracture, nonunion, AVN, Range of Motion (ROM), Harris Hip Score (HHS) and difference found between two limbs.

Statistical analysis: The data stated as Mean±SD (standard deviation), frequency and percentage. SPSS^TM 15 was used as the statistical program. The quantitative data was compared using independent sample t-test or Mann-Whitney U-test. Chi-square test or fisher exact test were used to compare qualitative data. In all cases, p<0.05 was regarded as significant.

RESULTS

A total of 60 patients were studied. Nine patients (5 from group A and 4 from group B) were not able to return after the first follow-up examination and were therefore excluded from the study. The remaining 51 patients consisted of 37 males (88%) and 14 females (12%). Considering surgeon comment on position of screws, there were 34 patients in the perfect group with mean age of 48.7±18.6 (18-80) and 17 patients in the imperfect group with mean age of 50.4±15.9 (19-80) years old. Patients' features and basic information of both groups were summarized and compared in Table 1. In this regard, there was no statistically difference between two groups. Follow-up results of the patients are summarized and compared in Table 2.

Table 1:	Features and basic information of the patients
Values in parenthesis are percentage

Table 2:	Results of patients' follow-up in both groups
AVN: Avascular necrosis, HHS: Harris hip score, ROM: Range of motion, *Non-parametric test, Values in parenthesis are percentage

Accordingly, mean of HHS in perfect and imperfect group was 75.5±2.3 and 68.1±3.9, respectively. There was a significant difference in this regard (p = 0.007). Also, mean of ROM was significantly more in the perfect group considering all cases (p<0.05). No statistically significant difference was observed in other characters. Nonunion was observed in 1 (2.9%) of the perfect group and 3 (17.6%) of the imperfect group. There was not any significant different in this regard (p = 0.102). AVN was registered in 2 (12.5%) of the imperfect group and none of the perfect group and there was not any significant different in this regard (p = 0.102).

DISCUSSION

This study considers results of femoral neck fracture treatment through placing three cannulated screws using the reversed triangle method. According to the results of our study and in comparing two groups with perfect and imperfect screw position from the surgeon’s viewpoint, no statistically significant difference was observed considering frequency percentage of nonunion and AVN. But, mean HHS and joint range of motion in all directions was substantially more in the group with perfect screw position. It should be noted that nonunion and AVN manifestation in the perfect group was more than the imperfect one but the difference was not substantial. It seems that this is due to small size of the studied sample especially in the group with imperfect results. It seems that comment of the surgeon in this regard significantly affects prognosis of the surgery. Therefore, the necessary actions required to improve the patients' conditions can be taken considering this result. Nonunion and AVN were observed in 7.8 and 3.9% of cases, respectively. In a study different methods of femoral neck fracture fixation was evaluated. Accordingly, the amount of nonunion was varied from 10-20% in these studies and different therapeutic methods (Raaymakers, 2006). Results of this study were more than this study considering malunion which is due to differences found in sample size, fixation methods, studying approaches and patients' features (such as age and gender). In a previous study, AVN has been reported about 11% which was more than those of our study (Asnis and Wanek-Sgaglione, 1994). It can be a result of shortness of this study follow-up period, non-benefiting of MRI in AVN diagnosis in weight intolerance areas and excluding younger than 18 years old patients with femoral neck fracture. In this study, HHS in the perfect group was significantly more than the imperfect group. The results of different studies in this area are varied. Different reasons including differences found in size of the studied sample, patients’ features (e.g., age and gender), severity of fracture, amount of primary displacement, study and follow-up methods, follow-up duration can be regarded as possible reasons in justifying these differences (Bouchoucha et al., 2011; Morochovic et al., 2011). It has been suggested that use of three screws instead of two in fixing this kind of fracture creates more stability (Rupprecht et al., 2011). The present study is of special importance because of limited studies regarding results of this type of femoral neck fracture fixation and specially lack of any similar study in the country. This study mainly considers effects of surgery evaluation about screw position on conditions of the patients. No similar study has been conducted in this regard. In a previous study, the authors concluded that screw position in femoral neck fracture fixation may have a significant effect on stability (Lindequist, 1993). Screw position is effective in final prognosis, too. In some studies, it has been demonstrated that 5-10 degree of diversion is acceptable (Bojan et al., 2010; Jansen et al., 2011; Vukasinovic et al., 2010).

CONCLUSION

Comparing two groups with perfect and imperfect position of the screw, according to the surgeon's comment, no statistically significant difference was observed considering frequency percentage of nonunion and AVN. But, mean HHS and joint range of motion in all directions in the group with perfect screw position was significantly high. Therefore, it seems that amount of nonunion and AVN has no relation with screw position and anatomic reduction and rigid fixation is more effective in treatment results, according to the results of this study.