Scientific Papers

Clinical versus radiological method for adjusting rotational alignment during femoral shaft fractures intramedullary nailing and the malrotation impact on the functional outcomes: early results from a prospective cohort study | Journal of Orthopaedic Surgery and Research

We found that there was no difference regarding the incidence of malrotation deformity after IMN of unilateral femoral fractures operated on a usual radiolucent table either after using an intraoperative clinical or radiological method for rotational adjustment; furthermore, the functional outcomes were not affected by the presence or the degree of malrotation, so both our hypotheses were disputed.

Malrotation is considered one of the most common complications when treating femoral shaft fractures using IMN [8, 9]. Various factors could lead to this problem, some of which are related to the characteristics of the fracture (such as configuration and comminution), some could be related to the surgical technique (such as using fracture table and patient position), and patient factors (such as operating on obese patients) [5, 8, 27, 28]. Moreover, the direction and the amount of malrotation are determined mainly by the fracture location and the muscles acting around the fracture [5]. The malrotation incidence documented in the literature varied among studies and was reported to occur in 35% to 42% of the patients [8,9,10,11, 17]. In the current study, we reported an incidence of malrotation of 48.5%, which is slightly higher than what is reported in the literature. Furthermore, most of the deformities (84.8%) were in external rotation, although we did not investigate the predisposing factors; this could be attributed to the muscle forces working around the fracture, about 52% of the included patients were obese or overweight, operating in a supine position, and not using a traction table [5, 6, 23]. However, we cannot deny possible surgical technique issues predisposing to the deformity, specifically using manual traction to maintain the reduction till final fixation [5, 8].

Suggested advantages of using a fracture table over a regular radiolucent one are the less assistance needed and maintenance of the fracture position while operating [28, 29]; however, it carries some complications such as nerve palsies, perineal soft tissue injuries, ankle joint pain, and possible increased risk of femoral internal malrotation [30]. We were comfortable operating all cases on the usual radiolucent operative tables while the patient was supine, using manual traction to assist fracture reduction. Some studies showed no difference in malrotation incidence according to the operative table type, as shown in a randomized study by Rashid et al. included 74 patients having femoral fractures treated with IMN; 37 were operated upon using a fracture table and 37 on a regular operative table, and the overall incidence of malrotation was 17.6% (76.9% of them were internally rotated), which was not different between both groups (p = 0.760) [29]. However, on the contrary, in a randomized study by Stephen et al. operating using a fracture traction table (42 patients) versus manual traction (45 patients), the authors reported significantly more internal malrotation (> 10 degrees) in patients operated on traction table compared to manual traction, 29% versus 7%, respectively (p = 0.007). Furthermore, they reported lower mean operative time with the manual traction technique than operating on a traction table, 119 versus 139 min, respectively (p = 0.033) [28].

Several techniques were described for obtaining proper rotation during IMN of femoral shaft fractures, including direct visualization (if an open reduction was performed), morphological fracture characteristics, and fracture reduction alignment under fluoroscopy [8, 15, 27, 31]. Furthermore, different techniques relying on using the uninjured contralateral side (either radiologically or clinically) as a template have been used by many surgeons [11, 22, 26]. In the current study, we did not encounter a difference in the incidence of malrotation after either the radiological or clinical method relying on the normal contralateral side. On the contrary, a study by Deshmukh et al. compared a radiological method while operating on a fracture table (by using the profile of the lesser trochanter on the intact side as a template) to a conventional clinical technique; the mean malrotation was 12.5° (range 6.4–17.7) with the clinical technique compared to 4.1° (range 0–9.9) with the radiological technique, the difference was significant (p = 0.016) [22]. In a study by Mansouri-Tehrani et al., who treated 140 patients with isolated femoral fractures using IMN over six years, intraoperative assessment of rotational profile was performed by clinical method, postoperative malrotation assessment using a CT scan showed a 15.7% incidence of malrotation of 10–15 degrees [32].

The caveat of using the contralateral side as a template originated from the possibility of deformity or version difference in the supposed normal contralateral side compared to the injured side [27, 33]. In a CT-based study by Croom et al. to evaluate the difference in femoral version between both sides in uninjured individuals, they included 164 subjects, the mean version difference between both sides was 5.4° ± 4.4, 17.7% had a difference in version ≥ 10 degrees, and 4.3% had a difference in version ≥ 15 degrees. They concluded that a possible difference in the femoral version between both sides could be present and proposed a 15 degrees difference as the point for considering malrotation [27].

We assessed the rotational profile by CT scan images; however, various methods, including clinical and radiological, for postoperative malrotation assessment were described, but both are unreliable and less accurate [8]; however, most surgeons rely on assessing the rotational profile by obtaining a CT scan of both sides, which proved to be an accurate and efficient method [34, 35]. We adopted the technique described by Jeanmart et al. [25], where the angle was calculated between the femoral neck axis and a line tangential to the posterior condyles, which was also utilized in the study by Karaman et al. [9]; however, various techniques using various lines were described [26, 27].

How much malrotation a patient can tolerate and compensate for is controversial among authors; most surgeons agreed that malrotation less than 10 degrees will pass unnoticed by the patient and easily compensated as it is considered within the normal variations limit, while malrotation above 15 degrees will be considered as pathological malrotation, and malrotation between 10 and 14 degrees is a grey or controversial zone [5, 8]. Some authors, such as Kent et al., raised the acceptance range of malrotation between 15 and 30 degrees, believing that most patients could tolerate this deformity amount [21].

The patient compensates for the malrotation by rotating the lumbosacral spine, hip joint, knee joint, and up to the foot and ankle; these compensatory mechanisms are more evident while walking [36]. However, If the malrotation was large enough, it could be noted by the patients and cause cosmetic disfigurement; furthermore, it could negatively affect these compensatory mechanisms, leading to lower hip and knee functional outcomes, less patient satisfaction, and patients’ daily activities affection [8, 9, 17, 18].

Although we had a relatively high incidence of malrotation compared to the literature, we achieved excellent or good functional outcomes in the hip and knee joints in 87.9% and 96.7% of the patients, respectively. Furthermore, according to Neer’s score, excellent or satisfactory results were obtained in 90.9% of the patients, and the presence and the degree of malrotation did not affect the functional outcomes.

The effect of femoral malrotation on functional outcomes differs among studies as it is affected by patients’ ability to compensate for the deformity; in a study by Bråten et al., although malrotation of more than 15 degrees was reported in 21 patients, only eight had a clinical complaint [37]. In a study by Gugala et al. on 16 patients, they reported internal rotation deformity (3–13 degrees) in five patients, while in 11 patients, an external rotation deformity (3–32 degrees) was evident, the authors reported no difference regarding patients satisfaction according to the deformity direction; however, external rotation deformity was better tolerated compared to internal rotation [38]. Furthermore, Mansouri-Tehrani et al. reported no correlation between femoral malrotation and clinical outcomes [32].

On the contrary, many authors reported that femoral malrotation affects functional outcomes, especially its negative effect on the patellofemoral joint, resulting in persistent anterior knee pain [10, 18, 26]. In a study by Karaman et al. on 24 patients who were treated by IMN for a unilateral femoral fracture, they reported an incidence of malrotation of about 42% as compared to the contralateral intact side; they reported lower TLKSS and WOMAC scores (for the knee and the hip joints) in patients with malrotation (no difference between external or internal deformity) compared to those who did not have deformity, patients complained mainly of anterior knee pain while climbing stairs and performing sports activities; furthermore, some patients in the malrotation group reported occasional hip pain [9].

We admit that the current study has some inherent limitations. First, we did not perform a sample size calculation before the study; however, we believe we included enough average number of patients compared to the previously published studies, enabling us to obtain sensible results. However, we admit that a larger sample-size study would be preferable. Second, is the lack of randomization. Third, we did not calculate the amount of radiation exposure from performing a CT scan to assess the rotational profile; however, according to the radiology department, the radiation was kept to a minimum within the range of accepted limits [39]. Last, the relatively short follow up period, as a longer follow up is needed to estimate the possible long-term effects of malrotation on the outcomes.

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