The main weight-bearing bone in the leg is the tibia, which bears more than 80% of the stress while the fibula is only thought to support between 7% and 16% of body weight normally [1]. Tibial fractures are common long-bone injuries, accounting for approximately 2 percent of all adult fractures [2]. Significant osteoporosis raises the chance of compound or more complex fractures, which are more likely to result in increased morbidity and mortality. High-energy trauma, most frequently from car accidents, causes more severe tibia fractures [3].

High-energy transverse and comminuted fractures are more common in patients under 30 years of age [1]. Tibia fractures have somewhat higher nonunion and malunion rates than fractures elsewhere in the body. The most frequent location for tibia fractures is the tibia diaphysis, and over 80% of these injuries also result in fibula fractures [4]. There are three basic types: Simple fractures (type A), wedge fractures (type B), and complex fractures (type C). Each fracture type is divided into three groups which denote increasing severity of injury [5]. Over time, nonoperative care for tibia shaft fractures has lost respect. The vast majority of adult tibia fractures are currently treated operatively in the developed world, despite the fact that the favoured method of surgical fixation differs geographically, by surgeon age and training [6]. In terms of nonunion, malunion, complications, and time to resume work, surgical fixation is preferable to closed therapy. The majority of displaced tibia shaft fractures are currently treated with surgery, with intramedullary nailing being the most popular surgical method [7].

The common surgical procedures included intramedullary nailing, minimally invasive plate osteosynthesis (MIPO), open reduction and internal fixation (ORIF), and external fixation [8]. Interlocking intramedullary nailing (IMN) is the mainstream treatment for tibial shaft fractures due to minimal soft tissue dissection, good bone union rate, and early return to daily living. IMN procedure had greatly improved over time resulting in these promising outcomes, and thus, its indications have been extended to fractures closer to joints [9]. The biggest drawback is how challenging it is to achieve and maintain appropriate reduction, especially in cases of proximal and distal shaft fractures with wide medullary canals. Studies have linked IMN to increased rates of misalignment and slower bone repair [8].

MIPO lessens the drawbacks of standard plating and offers stronger bone union, quicker wound healing, and fewer infection issues while causing less soft tissue injury. Additionally, it prevents anterior knee soreness. As previously said, IMN and MIPO each have advantages and drawbacks [10]. The aim of study is to compare the clinical and functional outcome between two groups of patients presented with tibial shaft fracture treated with IMN and MIPO.

A. Study design, setting, and time

This was a randomized clinical trial study conducted at Al-Yarmouk Teaching Hospital and other private hospitals, Baghdad, Iraq during a period of 17 months from September 2020 to January 2022 including a period of one year for follow up.

B. Study Population and sample size

The study included 40 patients complained from tibial shaft fracture, skeletally mature, their fracture was closed or open fracture gastello type I, with extra articular fracture shaft tibia, or distal and middle third fracture. Patients with polytrauma, open fracture gastello type II and III, skeletally immature, had pathological fracture, with diaphyseal fracture with intra articular extension, with proximal third fracture, patients who were missed in follow up, and those who refused to participate in this study were excluded. Tibia fracture categorized according to Orthopedic Trauma Association Classification (AO/OTA) as shown in Figure 1.

Figure 1: Orthopaedic Trauma Association Classification (AO/OTA)

The patients were divided into two groups:

• IMN Group: Included 20 patients treated by IMN;
• MIPO Group: Included 20 patients treated by MIPO.

C. Preoperative workup

Pre-operative demographic, clinical, and radiological evaluation considering age, mode of injury, operative time, fluoroscopy time, time for union. Data of the patients was collected, a complete medical and surgical history was obtained and full clinical systemic physical examination was performed. General examination of the patients and local examination of the injured limb were done involving assessment of vascular and neurological status with attention to soft tissue condition. Imaging plain x ray anteroposterior and lateral view of the injured leg showing whole tibia with knee and ankle joint were performed. Laboratory investigations were routinely ordered as CBC, PT, INR, RBS, RFT, Virology and Echo study in some patients according to clinical conditions.

D. Operative technique

All patients in both groups were operated within seven days. Pre-operative IV antibiotic within 30 mints. before surgery and all operations were done by the same surgical team.

E. IMN group

• Under general or spinal anaesthesia, the leg was prepared with washing and shaving.
• Pneumatic tourniquet applied to upper thigh.
• The patient was in supine with hip extended and knee flexed 90 degrees beside the table.
• Small incision about 3 cm is made from inferior pole of patella to tibial tuberosity (infrapatellar approach) in line with axis of intramedullary canal, patellar tendon retracted laterally (medial parapatellar approach) to reach the entry point, which was just medial to lateral intercondylar eminence when anterior tibia reaches the articular surface.
• Under fluoroscopy AWL inserted, before full surgical opening confirmation with AP and lateral image, then manual reduction of the fracture with traction and manipulation to allow placement of the guide wire, crossing the fracture advanced with 1-2 cm above ankle joint. Then reaming of the canal starting with size 8mm and gradual increase in reamer size.
• After reaming the leg put on table with knee semi flexed then chose the appropriate nail size (1mm less than the last reamer) and correct length according to tibia length.
• When the nail fully inserted the proximal end should lie about 0.5 cm below cortical opening.
• Check the alignment of fracture under fluoroscopy, rotation alignment by align the iliac crest with patella and second toe.
• Removing the guide wire and 2 distal and 2 proximal locking screws inserted percutaneously through small stab wounds from medial to lateral.
• Then cup used for proximal end of the nail. Then washing of the wound and suturing the deep layer with interrupted absorbable suture and the skin with nylon suture. Then deflate the tourniquet.

F. MIPO group

• Under general or spinal anaesthesia, patients in supine position with extended hip and knee.
• The leg prepared circumferentially from knee to toes, with shaving and washing.
• Pneumatic tourniquet applied to upper thigh.
• After sterilization a small longitudinal incision 3-4cm is made distal to the fracture site exposing tibia in the anteromedial side and submascular tunnel was made with periosteal elevator.
• Fracture reduction was achieved by traction and manipulation under fluoroscopy guidance, then locked plate inserted in the subcutaneous tunnel under fluoroscopy.
• After insertion of the plate and achieving good reduction, the plate temporarily fixed by holder, clump or wires.
• Distal fragment fixation was done with combination of locked and cortical screws depending on fracture pattern and quality of the bone.
• Then the proximal screws inserting through a small stab wounds.
• A minimum of purchase 6 cortices proximal and distal to the fracture site.
• The tourniquet deflated, to see if there is any bleeder which should be ligated or cauterised. Then washing and suturing of the wounds with nylon suture.

G. Postoperative management

Immediate post-operative x ray obtained (AP and Lateral). Neurovascular status was examined. Keep limb elevated postoperatively (for 5 days). IV broad spectrum antibiotic were prescribed for 3 days then oral antibiotic for one week. Analgesia prescribed to all patients. Encourage quadriceps muscle exercise, knee and ankle joints movement.

H. Follow up program

The follow up visits were scheduled after 2, 4, and 6 weeks, 3, and 6 months and one year. Clinical and radiological assessment performed during each visit. At two weeks, stitched removed and partial weight bearing with crutches as tolerated encouraged in patients treated with intramedullary nail.

At 4 and 6 weeks, assessment was done regarding range of motion, muscle strengthening and any complications and encourage partial weight bearing in MIPO group as tolerated. At 3 months, check for any signs of union, if full union occurred the patient instructed for full weight bearing.

At 6 months and 1 year, evaluation of the clinical and functional outcomes guided by JLETS.

I. Statistical analysis

The data analyzed using Statistical Package for Social Sciences (SPSS) version 26. The data presented as mean, standard deviation and ranges. Categorical data presented by frequencies and percentages. Independent t-test (two tailed) was used to compare the continuous variables between study groups. Chi square test was used to assess the comparison between study groups by categorical variables, while fisher exact test was used instead when the expected frequency was less than 5. A level of P - value less than 0.05 was considered significant.

In this study, no statistical significant differences (P \(\geq\) 0.05) between study groups regarding age as 70% of MIPO group and 75% of NAIL group aged < 40 years, gender as males represented most of cases (90% of MIPO group and 80% of NAIL group), mechanism of injury as RTA in 60.0% of MIPO group and 65.0% of NAIL group, type of fracture as AO type 42 A fracture was shown among 50% of MIPO group 40% of NAIL group, and location of fractures as mostly at distal shaft; 65% in MIPO group and 60% of NAIL group, (Table 1).

In healing process parameters, mean of time till partial and full weight bearing, time to union, and time to return to work were significantly lower (P < 0.05) in patients treated by IMN as shown in Table 2.

As shown in Table 3, knee pain was significantly higher (P= 0.001) in patients of IMN (no cases in MIPO group); while implant irritation and ankle stiffness were significantly higher (P < 0.05) in MIPO group (no cases in IMN group).

Rigid fixation with anatomical reduction is considered vital in obtaining a good functional outcome. In the early postoperative period IMN is superior to MIPO in term of partial weight bearing, full weight bearing, time to union, return to work, ankle stiffness and implant irritation, but both modalities have similar results in 6-12 months of follow up.

The author expresses appreciation to all patients who participated in this study and extends gratitude to all participating healthcare institutions for their cooperation and contribution.

The authors declare no conflicts of interest.

All authors contributed equally to this paper. They have all read and approved the final version.

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