Management of Neglected Femoral Neck Fracture in Young Adolescents with Modified Pauwels Osteotomy

Abstract

Background: 

Non-union of the femoral neck fracture in young is difficult to tackle. Many reported treatment methods for neglected femoral neck fractures do not always satisfactorily address the problems like non-union, coxa vara, and limb shortening. If the femoral head is viable, the most appropriate treatment is valgus osteotomy, which increases the femoral neck angle to change shearing force to compression force. We prospectively reviewed the functional outcome of the modified Pauwels’ osteotomy in 16 young adults to determine whether this approach would correct those problems.

Materials and Methods: 

A total of 16 cases of neck femur fracture in less than or equal to 16 year old neglected for more than 12 weeks were included in our study and were treated primarily by modified Pauwels intertrochanteric osteotomy with internal fixation. The patients were followed up to 12–24 months with radiography and were assessed regarding Harris hip score, unionand limb length discrepancy.

Results: 

Union was seen in all the 16 patients .11 out of the 16 patients showed excellent clinical outcome (Harris hip score ≥ 90) with an average Harris score of 90.1 ± 6.

Conclusion: 

Modified Pauwels’ Intertrochanteric Osteotomy is a safe and effective procedure in preserving the God gifted hip in neglected femoral neck fracture

INTRODUCTION

In developing countries, poverty, lack of proper facilities, lack of knowledge, faith in traditional healers and recently due to covid 19 lockdown femoral neck fractures are left untreated for several months.[¹²³⁴] In younger patients with fracture neck of femur, salvage of femoral head if viable is often the most justified treatment.[⁵⁶] On the other hand, with increasing life expectancy late complications of prosthetic replacement are increasing.[⁶] Pauwels commented that non-union and fixation loss in high- energy fractures are often caused by mechanical factors and hence they are more important than biological factors during healing of such fractures. In case of femoral neck fracture, these unfavorable shear forces are converted into favorable compression forces by valgisation osteotomy. Such osteotomy by aiding the mechanical forces, stimulates fracture healing.[⁶⁷⁸]

Pauwels classified fracture neck of femur into 3 types based on the fracture line inclination which dictates their mechanical behaviour. A vertical fracture line (in type 3) increases the risk of non-union because of maximum shear forces across the fracture site. Hence, Pauwels described an intertrochanteric abduction osteotomy to covert these shear forces in to compression forces by making the fracture line more horizontal.[⁶]

We attempted to answer four questions in our study: (i) What is the role of the modified Pauwels’ intertrochanteric osteotomy in neglected femoral neck fractures in young adolescents regarding union and functional out- come? (ii) Can an osteotomy correct the non-union/delayed union? (iii) Are our results using the osteotomy comparable with published results? (iv) Do any Limb length Discrepancy remain after union?

MATERIALS AND METHODS

It is a prospective study done from October 2019 to September 2021 in a tertiary hospital attached to Medical College (Department of orthopaedic surgery, Tezpur Medical College and Hospital, Assam).

16 patients were found suitable and included for study as per inclusion criteria (less than or equal to 16 years of age with femoral neck fractures neglected for more than 12 weeks presented with delayed union or non-union). Patients of >16 years and medically unfit were excluded from study. The study group comprised of 10 male and 6 female patient. Standard principle and method of Pauwel’s osteotomy was followed during operation in all cases [Figure 1a & b].

Figure 1: Schematic diagram of Principle of Pauwels osteotomy which converts shear forces into compression forces (A) and Operative steps with fixation (B) on which (A) Tracing of preoperative radiograph (B) AB-femoral shift axis AC-perpendicular to femoral axis EF and EG are proximal and distal limbs of osteotomy. A 20 degree wedge has been defined. H is the anatomic landmark for inserting chisel (C)intertrochanteric wedge of bone has been excised as per preoperative planning (D)Distal fragment is abducted and plate is stabilised with screws. Excised wedge of bone is placed in the elbow of implant

Surgical procedure

Step 1: Preoperative templating

Templating was performed on the normal hip, it gave information about positioning of implant and size of wedge to be taken out. Thereafter, the angle that the fracture made with horizontal was measured and the angle of correction or wedge angle was calculated as under:

Wedge angle (Osteotomy angle) = Shear angle – Postoperative desired angle (25º-30)

Thus, the desired post operative Pauwel’s angle was less than 30º.

Step 2: Reduction and stabilization

Closed reduction was attempted on fracture table with traction/ Leadbetter technique under guidance of image intensifier. The fracture was stabilized with Double angle DCS. The blade or screw was engaged in the inferior quadrant as cut though is observed when it is placed in superior quadrant.^[7 As per preoperative templating, osteotomy angle was marked and osteotomy was performed with power saw

Step 3: Osteotomy and fixation

Lateral closing wedge was taken from intertrochanteric region at the upper border of lesser trochanter, after which osteotomy was closed by abducting the limb and clamping the plate to bone.

All the steps of modified Pouwel’s osteotomy are shown in figure [Figure 2].

Figure 2: Intraoperative and flouroscopic images showing various steps of Modified Pauwel’s Osteotomy and fixation

Post-operative care

Post operatively partial weight bearing on the operated limb was allowed on Day 3 post-op/ when pain subsides and are encouraged to do hip and knee range of movement exercises. Full weight bearing is encouraged after 10–12 weeks after complete union of osteotomy site.

Follow up

The patients were followed up after 2 weeks when the suture removal was done. Thereafter, patients were followed up on a monthly basis and the functional outcome using Harris hip scores assessed at 6 weeks, 3 month, 6 month and 12 months.

RESULTS

As per the detailed demographic profile of patients [Table 1], our study included 16 patients of which there were 10 males and 6 female. The mean age of our study sample was10.6 ± 2.7 Years. The patients were operated at a mean time of 14.9 ± 2.4 from the day of trauma. All patients were followed up for a minimum period of 12 months to 24 months. The observation of result were recorded on various parameters. The average Harris hip score at the end of 12 months in the patients was 90.1 ± 6.6. Excellent results were achieved in 11 (Harris hip score more than 90) of the patients with Good in 3 cases and Fair in 2 cases. No patient had any serious immediate postoperative complication such as infection or DVT. All the 16 cases achieved clinical and radiological union. Union of fracture site was achieved at an average13.5 ± 2.6weeks. A 100% Union at the site of osteotomy was achieved in all the 16 cases. The average Pauwels angle post the operative procedure was 27.7 ± 2.3 degrees and average correction done was 27.33 ± 2.3 degrees The results are represented in table [Table 2].

Table 1: Patient characteristics with demographic profile

Table 2: Follow-up observation of results on various parameters including Harris Hip Score (HHS)

All the patients were able to sit cross legged, squat and do one leg stance [Figures 3 & 4]. No cases of non-union or avascular necrosis were recorded up to 12–24 months follow up.

Figure 3: Radiograph showing fracture neck of femur following failed osteosynthesis (A) which was treated by Modified Pauwel’s Osteotomy and showing complete union at fracture and osteotomy site in follow up x-ray at 4 months (B). Clinical pictures of same patients at last follow-up [c]

Figure 4: 6 months old fracture neck femur in 10 year old child (A) showing Union at osteotomy and fracture site at 3 months follow-up (B). Clinical pictures of same patients at last follow-up (C)

Limb-length equalization was achieved in 3 of the 16 patients with preoperative shortening. Limb length shortening seen in 4 cases and lengthening in 9 cases with average post-operative lengthening 2.1 ± 0.8 cm.

DISCUSSION

In our case series, union was achieved in all the cases with 11 out of the 16 patients having an excellent outcome. Our findings are comparable to results obtained by other authors opting for modified Pauwels osteotomy as a primary mode of treatment in neglected neck of femur fractures [Table 3]. Magu et al. reported 94% union rate in their study on 50 cases femoral neck fractures. Excellent to good outcome were reported in 76% of the patients with an average Harris hip score of 92 and the average time of union reported was 12.2 weeks.[⁹] Ansari et al. performed osteotomy in 15 fresh cases of femoral neck fractures with an initial average Pauwel’s angle of 59º and reported excellent result in 7 cases and good result in 4 cases. The time for union was between 4 to7 months in all the cases.[¹⁰] Rinaldi et al. reported bony union in 25 consecutive cases of fracture neck of femur treated by primary osteosynthesis and modified Pauwels osteotomy.[¹¹] Rotolo et al. reported 100%union in all cases of subcapital femoral neck fractures treated with primary intertrochanteric osteotomy.[¹²] Probably we got more neglected cases because of covid 19 pandemic resulting in lockdown, in this remote area of Northeast India.

Table 3: Comparison of our result with published literature

CONCLUSIONS

Modified Pauwels’ Intertrochanteric Osteotomy is a safe and effective procedure in preserving the God gifted hip in neglected, delayed/non-united femoral neck fractures and in some acute fractures with high Pauwels angle. Functionality of the hip is restored in the majority of patients. However, slight leg length discrepancy and limp remains in some patients. Valgus overcorrection should be avoided to prevent procedure related avascular necrosis and early degeneration of the hip. Lateral displacement of the femur should be kept to a minimum to facilitate future hip replacement if needed. A large scale study with a longer duration of follow up is necessary to further assess the efficacy of the procedure.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.