Fracture of the humeral shaft is common, accounts for approximately 3% of all orthopedic injuries, and results in a significant burden to society from lost productivity and wages. Complications can include nerve and blood vessel damage (especially the radial nerve), malunion (poor alignment), and non-union (non-healing) ^[1,2,3].

The conflict between the need for absolute anatomical reduction and, at the same time, the desire for soft-tissue preservation has been going on for a long time. Not only solid healing, but also immediate and continuous function of the limb is now a leading goal. However, precise reduction and absolute stable fixation has its biological price ^[4].

There has been evidence to show the superiority of biological fixation over a stable mechanical fixation ^[5]. This led to the development and improvement in the techniques of biological fixation for fractures, and also the development of stabilization systems that help in achieving a biological fixation ^[6,7].

Open reduction with internal fixation is a common treatment method. However, these methods involve great trauma and a risk of iatrogenic radial nerve injury of 5.1–31.3%, and there are high chances of non-union and delayed union ^[8,9].

The minimally invasive percutaneous plate osteosynthesis (MIPPO) technique is reported as a satisfactory procedure for the treatment of humeral shaft fractures by the anterior approach by several authors. MIPPO is emerging as an effective alternative.

In the treatment of humeral shaft fractures, three surgical approaches, namely, the anterior approach, anterolateral approach, and posterior approach, are commonly used. Each has its advantages and disadvantages.

We hypothesize that a minimally invasive anterior bridge plating approach for internal fixation of middle and distal third extraarticular humeral fractures is feasible, poses minimal risk of neurovascular injury, and can be effectively used to manage these fractures while allowing assessment of their proximity to adjacent neurovascular structures.

One of the advantages is the long working length of the anterior bridge plate technique. Working length is the distance between the nearest screws on either side of a fracture when a plate is used for fixation. It determines the stiffness and flexibility of the plate–bone construct. Long working length helps in more flexibility and promotes secondary bone healing (callus formation). Short working length helps in more rigidity and a higher risk of stress concentration and implant failure. Working length is important in bridge plating, minimally invasive plate osteosynthesis, and comminuted fractures ^[10,11].

<H2>Operative management

The patient was positioned supine on a radiolucent table with the elbow in mild flexion. Screw position, fracture site, and incision sites were marked (Fig. 1a and b).

A proximal deltopectoral incision was made using the biceps groove and pectoralis tendon as landmarks, exposing the proximal diaphysis lateral to the biceps tendon. A distal midline incision was made 1–2 cm proximal to the antecubital crease and extended proximally (Fig. 1c and d).

The interval between the biceps and brachialis was developed; the biceps was retracted medially, and the lateral antebrachial cutaneous nerve was identified and protected (Fig. 1e). The brachialis was split longitudinally, and the forearm was maintained in supination to protect the radial nerve.

Fracture reduction was achieved under fluoroscopy, ensuring acceptable alignment (<20° anterior angulation, <30° varus/valgus, <3 cm shortening). A submuscular extraperiosteal tunnel was created connecting both incisions using an MIPPO elevator (Fig. 1c).

Without radial nerve exploration, a locking compression plate was inserted (Fig. 1f). The proximal plate was fixed with one unlocked screw and contoured as needed (Fig. 1g and h). Additional locked screws were placed proximally, followed by distal fixation after confirming alignment.

Fracture compression was applied to reduce distraction, and rotational alignment was checked against the contralateral limb.

Cadaveric incision and plate placement are shown in Fig. 2, and intraoperative plate placement with C-arm guidance is shown in Fig. 3.

A total of 13 patients were selected for the study. There were 7 males and 6 females. The study protocol was approved by the institutional ethics committee, and written informed consent was obtained from all patients before inclusion in the study. All patients were treated with minimally invasive anterior bridge locking compressive plate fixation.

The inclusion criteria were as follows: (1) Diagnosis of unilateral closed humeral shaft fracture by imaging examination; (2) no neurovascular injury; and (3) patient consent to undergo surgery.

The exclusion criteria were as follows: (1) Pathological fracture; (2) associated nerve injury; (3) open fracture: Gustilo and Anderson type 3 open fracture; (4) history of mental illness or cognitive impairment; or (5) severe systemic disease resulting in an inability to tolerate surgery; (6) injury severity score >16.

<H2>Post-operative care

A sling was used for comfort for the first 2 weeks postoperatively. Active and assisted range-of-motion exercises of the shoulder and elbow were initiated immediately without restriction and were gradually increased, with emphasis on achieving full elbow extension. Minor functional limitations were maintained until radiographic evidence of bridging was observed, and unrestricted activity was typically resumed at 4–6 months.

The disability of arm, shoulder, and hand score was used to evaluate post-operative recovery. The shoulder and elbow function was assessed using the University of California at Los Angeles shoulder rating scale and Mayo elbow performance score (MEPS), respectively.

A total of 13 patients were included in this study, which were described in Table 1. Out of which 2 cases are described as Case 1 (Fig. 4, 5, 6) and Case 2 (Fig. 7, 8, 9). A total of 7 were male (53.8%), and 6 were female (46.2%). Out of 13 patients, 9 cases (69.2%) had injury in their dominant arm, and 4 cases (30.8%) had injury in their non-dominant arm.

Road traffic accident was the most common mode of injury, being reported by 10 cases (76.9%); the rest sustained injury following a fall on an outstretched hand, 2 (15.4%) cases, and direct trauma, 1 (07.7%) case. Mechanism of injury shown in Table no 2.

The mean follow-up of our cases was 12 months. Union was observed at a mean period of 12.9 weeks (range: 10–20 weeks). In 2 cases, where there was scanty callus at 12 weeks, which was kept under masterly observation, and these patients showed good union at 20 weeks. We accepted up to 5° of varus/valgus angulation intraoperatively and on following these patients, in 10 (76.9%) cases, of the cases the angulation had remodeled to correct alignment. In the remaining 3 cases, 2 had 3° of varus, and 1 had 5° of valgus.

Some degree of malunion of the humeral shaft fracture is acceptable because the shoulder function is compensated for by the wide range of motion of the glenohumoral joint. Klenerman reported that acceptable deformity of the humerus includes anterior angulation <20, varus or valgus <30, and shortening <2–3 cm ^[12].

At the 1-year postoperative follow-up, with no cases (0%) of infections. One patient (07.7%) had developed neuropraxia, which eventually recovered. Final evaluation showed full neurological recovery. Shoulder function was excellent in 11 (84.6%) cases and good in the remaining 2 cases (15.4%) on the University of California-Los Angeles score, as shown in Table 3. Elbow function was excellent in 9 (69.2%) cases, good in 2 (13.4%) cases, and fair in 2 (13.4%) cases on the MEPS, as shown in Table 4.

The present study demonstrates that MIPPO using an anterior bridge plating technique provides reliable union and favorable functional outcomes in humeral shaft fractures. All fractures in our series united at a mean of 12.9 weeks, which is comparable to previously reported outcomes with biological fixation techniques ^[13,14,15]. The consistent union observed may be attributed to preservation of the fracture hematoma and periosteal blood supply, key principles underlying secondary bone healing ^[13].

Iatrogenic radial nerve injury remains a major concern in operative fixation of humeral shaft fractures, with reported rates ranging from 5.1% to 31.3% in open techniques ^[8,9]. In contrast, no permanent nerve palsy was observed in our series, and only one case of transient neuropraxia (7.7%) recovered completely. The anterior approach avoids direct manipulation of the radial nerve and utilizes a relatively safe anatomical plane, which likely explains the low incidence of nerve-related complications, consistent with previous reports ^[14,15].

Functional outcomes in this study were favorable, with 84.6% of patients achieving excellent shoulder function and the majority demonstrating excellent-to-good elbow scores. These results are comparable with existing literature and reflect the advantage of minimal soft-tissue disruption, which facilitates early mobilization and preservation of joint function ^[14,15].

Minor angular malalignment observed in a few cases did not adversely affect functional outcomes and showed remodeling over time. This aligns with previously described acceptable limits of deformity in humeral shaft fractures, owing to compensatory shoulder motion ^[12]. Furthermore, the use of a long working length in bridge plating likely contributed to optimal construct flexibility, promoting callus formation and reducing implant-related complications ^[16].

The absence of infection and implant failure in our study further supports the biological and minimally invasive nature of this technique. However, limitations include the small sample size and lack of a control group. Larger comparative studies are necessary to further validate these findings.

The minimally invasive anterior bridge plate approach for the treatment of fractures of the middle and distal thirds of the humerus has some limitations. This clinical therapeutic study included a small number of cases, and this MIPPO technique is not suitable for proximal humeral fractures; there is not enough space proximally for screw fixation, resulting in a smaller amount of humerus available for purchase than in the lateral or anterior-lateral MIPPO approach, which allows the entire humerus/head to be available for purchase.

The limitation of the study was that we did not have a control group for comparison or another group treated with some other technique of humeral diaphyseal fracture fixation. A larger multicenter study with control groups will help us to arrive at a definitive conclusion.

The present study involving the MIPPO technique in the treatment of recent humerus shaft fractures has shown the procedure to be safe and effective with minimal soft-tissue injury and no major complications. Fracture union is augmented by the process of bridging callus, which progresses to complete union. This retrospective case series substantiates the superiority of the MIPPO technique as an effective method of shaft humerus fracture fixation with fewer disadvantages and shorter fracture union time and fewer incidences of radial nerve palsies.

Minimally invasive anterior bridge plating (MIPPO) for humeral shaft fractures is a safe and effective technique that preserves soft tissue biology, minimizes the risk of radial nerve injury, and allows early mobilization with excellent functional outcomes. It is a reliable alternative for extra-articular fractures of the middle and distal humerus.