ABSTRACT
The propose of this study was to asses the factors leading to complications in trochanteric femoral fractures treated with Dyna locking trochanteric (DLT) nails in geriatric patients, with respect to fracture stability pattern, postoperative reduction, screw placement, tip-apex distance (TAD), bone quality, and patient positioning.
One hundred sixty nine patients operated using DLT nail, aged 65 years and older with a minimum follow-up of 12 months were screened retrospectively. The fracture patterns were grouped as AO Foundation/Orthopedic Trauma Association (AO/OTA) 31-A1, A2, and A3, and the patients were operated in the supine position using a traction table, in the supine position without using a traction table, or in the lateral decubitus position. Postoperative bone mineral density (BMD) measurements were performed in all patients. The Fogagnolo criteria, modified from Baumgartner, were used to evaluate the fracture reduction, and accordingly, the fracture reduction was subdivided into good, acceptable, or poor. TAD measurements were performed as described by Baumgartner. The position of the lag screw within the femoral head was determined according to Cleveland and Bosworth method, and the central-central and infero-central positions were evaluated as optimal and the other positions as suboptimal.
A total of 57 complications were determined, of which 14 (8.2%) were cut-out, cut-through, and intrapelvic migration of the lag screw and distal peri-implant fractures requiring additional interventions. A statistically significant association was found between suboptimal lag screw placement, decreased BMD, TAD measurement >25 mm, and decreased reduction quality with cut-out, cut-through, intrapelvic migration, and varus collapse. Varus collapse was seen at a significantly low rate in AO/OTA 31-A1 type fractures and in surgeries performed with a traction table (p=0.004, p<0.001), although there was no association between cut-out, cut-through, intrapelvic migration and fracture type and patient positioning (p=0.542, p=0.632). The optimal lag screw placement and TAD measurements were statistically significantly better in patients who were treated on a traction table (p<0.001, p<0.001).
Decreased BMD, suboptimal lag screw position in the femoral head, a TAD of >25 mm, unstable fracture patterns, and poor reduction quality have an impact on complications. Performing the surgical intervention on a traction table ensures more favorable lag screw placement.
Keywords: Trochanteric, femur, fracture, DLT, cephalomedullary, complication
INTRODUCTION
Hip fractures in elderly patients are still a common and challenging issue. Early and appropriate surgical treatment thereby obtaining earlier mobility of these patients is essential to be able to avoid increased rates of complications and mortality (1).
Factors affecting the results of trochanteric hip fractures have been extensively studied in the literature. Bone quality, fracture stability and reduction, and proper selection and placement of the implant, have been defined as important determinants for better outcomes (2).
Intramedullary implants are the most preferred devices if internal fixation is applied to a trochanteric femoral fracture (3). The Dyna locking trochanteric (DLT) nail (U&I corporation, 20, Sandan-ro 76beon-gil, Uijeongbu-si, Gyeonggi-do, Korea) is one of the many intramedullary implants that provides better purchase in the osteoporotic femoral head and neck by using a lag screw with 3 wedge wings, thereby preventing complications.
There are very few published studies have reporting the results of trochanteric femur fractures treated with DLT nails (4,5). The aim of the present study was to evaluate the factors leading to complications in geriatric trochanteric femoral fractures treated with DLT nail, with respect to fracture stability pattern, postoperative reduction, screw placement, tip-apex distance (TAD), bone quality, and patient positioning during surgery.
METHODS
The orthopedic trauma database of a single center was retrospectively searched for patients who had sustained a hip fracture, including the femoral head, neck, peritrochanteric, and subtrochanteric femur fracture between January 2016 and December 2019. Approval was obtained from the Clinical Research Ethics Committee of Marmara University Faculty of Medicine (protocol code: 01.2020.578, date: 21.01.2020). Informed consent was provided by all patients, by their parents/legal guardians.
The study inclusion criteria were as follows:
1) Patients aged >65 years,
2) Followed up for at least 12 months,
3) Acute traumatic trochanteric femur fracture (AO 31-A1, A2, A3),
4) Treated with internal fixation with DLT nail.
The study exclusion criteria were defined as age <65 years, pathological fractures, patients with an associated fracture in the ipsilateral extremity, a follow-up period of less than 12 months, treated with implants other than DLT nail, or X-ray quality unsuitable for radiological evaluation. Data were retrieved from patient files related to age, fracture side, surgery time, blood loss, positioning during surgery, and duration of hospital stay.
The study was conducted on a total of 169 patients who met the criteria, comprising 72 males and 97 females with an average age at the time of injury of 78.6 years (range, 65 to 103 years) (Figure 1).
Surgical Technique
The operations of the patients evaluated in this study were performed by 7 surgeons. All surgeons are highly experienced in hip trauma. DLT nails were used in all cases as the implant for internal fixation. Surgical interventions were performed in three patient positions according to the surgeon’s preference: the supine position with a traction table, supine position with manual traction, and lateral decubitus. The fracture reduction was achieved through the closed or open technique. Intraoperative fracture reduction and implant position were confirmed using C-arm fluoroscopy.
Radiological Evaluation
Fractures were classified according to the AO/OTA classification on preoperative anteroposterior (AP) and lateral radiographs of the hip (6).
On immediate postoperative AP and lateral radiographs of the hip,
- Fogagnolo criteria modified from Baumgartner were used to evaluate the fracture reduction. The reduction was sub-grouped as good, acceptable, or poor (7).
- Varus and valgus malalignment were evaluated by measuring the neck-shaft angle of both hips, with malalignment accepted as >5° varus or >15° valgus compared to the contralateral hip (8).
- TAD was measured as described by Baumgartner (9).
- The position of the lag screw was determined according to the Cleveland and Bosworth method, in which central-central and inferior-central placement of the lag screw is accepted as the optimal position, and any other placement is suboptimal (10).
All fracture classifications, radiological evaluations, and measurements were performed by an independent observer.
Follow-up Protocol
Immediate weight-bearing as tolerated was permitted for all patients. Follow-up examinations, both radiological and clinical, were carried out at 3-week intervals until the third month, and after that every 3 months until the end of the year. The patients were informed that if any complaints developed, they should attend immediately without waiting for a routine follow-up appointment. In all patients, bone mineral density (BMD) measurements were taken using dual energy X-ray absorptiometry within 3 weeks after surgery.
Statistical Analysis
Data were analyzed using SPSS for Windows (version 15.0) software (SPSS Inc., Chicago, IL, USA). The conformity of the data to a normal distribution was evaluated using the Kolmogorov-Smirnov test. For assessing the study data, in addition to descriptive statistical methods (average, standard deviation, median, frequency, ratio, minimum, maximum), the Independent samples t-test was used to compare normally distributed parameters between the groups and the Kruskal-Wallis test and Mann-Whitney U test were used to compare non-normally distributed parameters between the groups in the comparison of quantitative data. Categorical data were compared using the chi-square and Fisher’s Exact tests. A value of p<0.05 was accepted as statistically significant.
RESULTS
The data of the patients, including fracture classification and reduction type, reduction quality of the fracture, lag screw position in the femoral head, TAD measurements, surgical position, and BMD measurements are shown in Table 1.
Complications
A total of 57 complications were determined, of which 14 (8.2%) were cut-out, cut-through, and intrapelvic migration of the lag screw, and distal peri-implant fractures requiring additional surgical interventions (Table 2).
Cut-out, Cut-through and Intrapelvic Migration
These complications were determined in 11 patients (6.5%), comprising 9 cut-out, 1 cut-through, and 1 intrapelvic migration, which required revision (Figure 2, 3). These complications were seen at a mean 3.6±4 months (range, 2 weeks -15 months) after surgery.
Varus Collapse
Varus collapse was accepted as a difference of >5° between the immediate postoperative and final follow-up X-ray measurements. Varus complication was the most frequently seen complication, determined in 36 patients at mean 2.5±1 months (range, 3 weeks-5 months) after surgery.
A statistically significant association was found between suboptimal lag screw placement, decreased BMD, TAD measurement >25 mm, and decreased reductin quality, with cut-out, cut-through, intrapelvic migration, and varus collapse (Table 3). Varus collapse was seen at a significantly low rate in AO/OTA 31-A1 type fractures and in surgeries performed with the use of a traction table (p=0.004, p<0.001). No association was determined between cut-out, cut-through, intrapelvic migration and fracture type and patient positioning (p=0.542, p=0.632) (Table 3).
The optimal lag screw placement and TAD measurements were statistically significantly better in patients who were treated on a traction table compared with the manual traction and lateral decubitus groups (p<0.001, p<0.001) (Table 4).
DISCUSSION
Hip fractures are one of the most common fractures requiring surgical intervention in the aging population and have an important place in routine orthopaedic practice worldwide. It can be defined as a fracture requiring urgent treatment as delayed treatment results in increased mortality rates (11).
The most appropriate implant for use in internal fixation of trochanteric femur fractures remains a matter of controversy (12-14). Osteoporosis and fracture stability are issues affecting whether cephalomedullary nail or extramedullary implants should be used (15). However, cephalomedullary nails are the most frequently preferred implants regardless of the experience of the surgeon, and the use of these nails has become accepted worldwide over the last three decades (3,16). Cephalomedullary nails have biomechanical superiority in respect to axial load sharing compared to extramedullary implants, and therefore have better failure resistance for unstable trochanteric fractures (17-19). In this study, DLT nail was used for all patients as the implant for internal fixation. This nail has three wedge wings on the lag screw for better purchase in the osteoporotic femoral head and has the biomechanical advantages of an intramedullary nail (4,5).
Many studies of trochanteric femur fractures in the geriatric patient population have focused on complications after internal fixation (8,20,21). In the current study cut-out, cut -through and intrapelvic migration was determined in 11 patients (6.5%), including 9 cut-out, 1 cut-through, and 1 intrapelvic migration. The cut-out rates are mixed for DLT nail, with a rate of 25% reported in one study, and no cases in another (4, 5). Some risk factors have been well described for cut-out, cut-through, and intrapelvic migration. A meticulous surgical technique including good reduction quality, TAD measurement <25 mm and central-central or inferior-central placement of the lag screw are modifiable and essential factors for avoiding complications and obtaining better surgical outcomes (2,8,22,23). The current study findings were similar to previous reports in the literature, which have shown a significant association between increased cut-out, cut-through, intrapelvic migration and suboptimal screw placement, TAD of >25 mm, and poor reduction quality.
The surgical interventions in the current study were performed in three different surgical positions according to the surgeons preference: supine with a traction table, supine with manual traction, and lateral decubitus position. The use of a traction table resulted in more favorable TAD measurements and lag screw placement compared with manual traction and the lateral decubitus position. Cut-out, cut-through, and intrapelvic migration were also seen to be fewer, but the difference was not statistically significant.
Varus collapse is another frequently seen complication resulting in femoral shortening and alterations in the gait (4,24,25). In a biomechanical study by Tisherman et al. (26), it was reported that distal locking of the nail could prevent collapse in cases with an osteoporotic unstable fracture pattern. Using a helical blade rather than a lag screw, especially in reverse oblique and transverse fractures, has also been suggested as another preventative method against collapse (25). Selecting the appropriate nail diameter to fill the medulla has a movement-limiting effect, and may therefore slow the rate of varus collapse (27). As using a helical blade and selecting a large nail are methods that provide better purchase in osteoporotic bone, this suggests that BMD has an important impact on varus collapse. The findings of the current study support this view with the determination of a significant association between a higher rate of varus collapse and decreased BMD. The findings of the current study also revealed a relationship between suboptimal screw placement, TAD measurement >25 mm, poor fracture reduction, unstable fracture pattern, and a higher rate of varus collapse. Patients who underwent surgery on a traction table suffered less varus collapse, which could be attributed to more favorable lag screw placement.
Peri-implant fracture is another devastating complication reported at rates of 1.7% and 2.3% in two meta-analyses, and which was seen in 3 (1.8%) patients in the current study (14,28). Distal locking is a controversial issue in peri-implant fractures and has been thought to be due to the nail tip leading to increased stress concentration, and thereby causing secondary fractures (29). However, this hypothesis was disproved by the same author, suggesting that distal locking served to prevent postoperative femoral fractures (30). Using long nails and slotting of the distal tip of short nails has been shown to result in lower rates of peri-implant fracture (31,32). Increased femoral bowing was determined in all 3 patients in the current study. Skála-Rosenbaum et al. (30) stated that increased femoral bowing and the distal tip of the nail touching the anterior femoral cortex may cause fracture through increased stress concentration. As a technical trick, choosing a slightly anterior entry point in the sagittal plane may permit the nail tip to be oriented from anterior to posterior, and thus a space can be provided between the anterior femoral cortex and the distal nail tip.
There were some limitations to this study, primarily the retrospective design, and that only the results of DLT nail were presented without comparison with any other implant. The preoperative functional status, comorbidities, and postoperative functional outcomes of the patients were not assessed. The interventions were performed by several different surgeons. There is need for further prospective, randomized studies comparing the DLT nail with other implants to provide more valuable information. However, this study can be considered of value as it included the largest number of patients treated with DLT nails.
CONCLUSION
The complication rates for DLT nails are comparable to those for other implants. Decreased BMD, suboptimal lag screw position in the femoral head, a TAD >25 mm, unstable fracture patterns, and poor reduction quality impact complications. Performing the surgical intervention on a traction table provides more favorable lag screw placement. The DLT nail can be used safely for internal fixation of trochanteric femur fractures with care taken to apply a meticulous surgical technique.
ETHICS
Ethics Committee Approval: Approval was obtained from the Clinical Research Ethics Committee of Marmara University Faculty of Medicine (protocol code: 01.2020.578, date: 21.01.2020).
Informed Consent: Informed consent was provided by all patients, by their parents/legal guardians.
Authorship Contributions
Surgical and Medical Practices: S.İ., Concept: S.İ., T.O., Design: S.İ., T.O., Data Collection or Processing: S.İ., Analysis or Interpretation: T.O., Literature Search: S.İ., T.O., Writing: S.İ., T.O.
Conflict of Interest: No conflict of interest was declared by the authors.
Financial Disclosure: The authors declared that this study received no financial support.
