A PROSPECTIVE STUDY TO EVALUATE FUNCTIONAL OUTCOME OF MINIMALLY INVASIVE PLATE OSTEOSYNTHESIS (MIPO) IN DIAPHYSEAL HUMERUS FRACTURE

Introduction: This study assessed clinical outcomes and complications in patients with humeral diaphyseal fractures treated using MIPO by means of

Fractures of the shaft of humerus have been treated conservatively since ages, with good results. Sir John Charnley in his treatise "The closed treatment of common fractures "even states"it is perhaps one of the easiest major long bone fractures to treat by conservative methods" 3 . Most of the humeral shaft fractures are best treated non-operatively with fairly high union rates 4,5 . However not all humeral shaft fractures are eligible for conservative treatment and indications for operative management in some situations remains apart 6,7 .
Historically used methods of conservative treatment include skeletal traction,abduction cast, coaptation splint, velpeau dressing, and hanging arm cast. All has its own advantages and disadvantages like joint stiffness and also it needslong period of rehabilitation to restore motion in the immobilized joints 6,8 .
Operative intervention is indicated in special circumstances including failure of closed reduction, intraarticular extension, neurovascular compromises, floating elbow, pathological fractures, open fractures, bilateral humeral shaft fractures, and poly traumatized patients. With recent advances, encouraging results following internal fixation had led to the expansion of surgical indications.
There are various surgical intervention by which fracture shaft humerus is treated by means of plating osteosynthesis 9,10 , intramedullary nails, or external fixation [10][11][12] . Although controversy exists over which is the better technique and implant, most authors believe that open reduction and internal fixation with a dynamic compression plate is a more reliable method.
The advantages include anatomical reduction of fractures and less interference to elbow and shoulder function 9,13 . The major disadvantages of this technique, however, are extensive soft tissue stripping and disruption of periosteal blood supply, which increase the risk of non-union and iatrogenic radial nerve palsies 14,15 . Humerus intramedullary nail is also consider as good implant as it is less invasive procedure but it associated with impingement at shoulder joint. It has been reported that humeral shaft fractures can be successfully treated with minimally invasive plate osteosynthesis (MIPO) 16-19. This technique has advantages of less soft tissue dissection and avoids the need to expose the radial nerve; thus, there is also low risk of iatrogenic radial nerve palsies 17 . These advantages appear to indicate that MIPO is superior to conventional plating osteosynthesis.
In this study, we will review our experience of treatment of diaphyseal humerus fractures with Minimally invasive percutaneous plate osteosynthesis (Anterior Bridge Plate) to analyse the functional outcome.

Material and Methods:
This study was done prospectively in the Department of Orthopaedics and Trauma Centre in J. A. Group of Hospitals, Gwalior (M.P.) from December 2015 to August 2017.

Sample Size:
Patients among the age group 16 years to 60 years were included in this study based on inclusion criteria and exclusion criteria and they were followed up, after the intervention till union. In this Prospective Study we study 30 diaphyseal humerus fractures treated with Minimally invasive percutaneous plate osteosynthesis (MIPPO) .

Pre-operative planning:
Detailed clinical history including mechanism of injury and patient's overall medical status, age and function and economical demands was taken and clinical examination was done for each patient. Routine blood and radiological investigations were carried out. Radiological examination included Antero-Posterior and lateral view of arm. The fractures were classified according to the AO/OTA classification 20 , Gustilo-Anderson classification 21 Data collection procedure included detailed study variable like preoperative and postoperative clinical, radiological, surgical and functional status of involved extremity.

Minimally Invasive Percutaneous Plateosteosynthesis (MIPPO):
Minimally invasive percutaneous plate osteosynthesis (MIPPO) means that plate is placed through small incision with as little dissection and stripping of soft tissue envelope as possible. It is also known as sub muscular, minimal incision and less invasive plating. Measures like smaller incisions, less soft tissue dissection, less periosteal stripping, use of intra-operative imaging or intra operative navigation preserve local blood supply, improving healing rates and reduce complications. In this study we did Anterior Bridge Plate by minimally invasive percutaneous plate osteosynthesis (MIPPO) technique. Both DCP and locking plates can be applied through MIPPO technique 22 .
In this technique since there is no disturbance of fracture haematoma so there is no need of absolute reduction so there is relative stability due to which healing take place by secondary intention (indirect healing), it is also known as biological fixation.
Plate length should be two to three times bigger than length of the fracture in comminuted fractures and eight to ten times higher in simple fractures 23,24 .

Number of screws:
Two screws on each side of the fractures are prerequisite for a stable construct. But, being on the safer side it is recommend to use three screws on either side so as to take care of chances of failure due to screw breakage. A plate screw density below 0.4 to 0.5 is recommended, this implies that less than half of the plate holes are occupied by screw 23,24 Surgical Approach 25 : Patient is in supine position, with arm resting on surgical table and elbow flexed to approximately 70 degree A 3-cm incision between the proximal biceps and the medial border of deltoid, 6 cm distal to the anterior part of the acromion process was made. The cephalic vein lies in this interval. Identify the vein and protect it while dissecting through the interval. Dissect bluntly to the periosteal surface. Distally, a 3-cm incision was made along the lateral border of the biceps, approximately 5 cm proximal to the flexion crease. The site of incision was confirmed under the image intensifier and altered, if necessary, to be as far as away as possible from the fracture site. The biceps was retracted medially to expose the musculocutaneous nerve, which overlies the brachialis muscle. The brachialis muscle was split and the musculocutaneous nerve retracted medially, and the radial nerve was protected by the lateral half of the brachialis muscle. A sub-brachialis, extra-periosteal tunnel was created by passing an artery forceps, used as a tunnelling instrument, deep to the brachialis muscle from the distal to the proximal incision. Care was taken to pass the tunnelling instruments anteriorly or anteromedialy to avoid the chances of injury to the radial nerve. After creating the tunnel, anarrow locked compression plate or dynamic compression plate was passed deep to the brachialis. The plate position and reduction was visualized on the image intensifier. Manual traction was applied to restore length and correct varus or valgus angulation and rotation. The plate was temporarily fixed to the bone with 2-mm K-wires.
Ensuring that the position of the plate on the distal fragment was central, it was fixed with a locking screw and, similarly, the proximal fragment was also fixed. After confirmation of the reduction, alignment on the image intensifier other screws were inserted to complete the fixation. • Evaluation of any possible loss of reduction. • Assessment and analysis of any complication.

Outcome Measures:
The Patient were assessed using • UCLA Shoulder rating scale for shoulder movement function  The age of patients ranged from 16 to 60 years with the fracture being most common age group is between 16-29 years of life.  In our study most of the injuries were caused by road traffic accidents affecting mostly males. We had 17 (56.66%) RTA injuries, 02(6.66%) due to Assault, and 11(36.66%) due to Fall on outstretched hand.   In our study average blood loss for MIPPO procedure is 114 ml. In our study average operative time for MIPPO procedure is 60 minutes. In MIPPO Group average time for union is 11.73 weeks in which 28 patients (93.33%) got united in between 8-12 weeks, 1 patient (3.33%) have union in between 12-16 weeks and 1 patient (3.33%) have union takes more than 20 weeks.  We had 3(10%) patients with complication includes Superficial infection in 1(3.33%) patient, Shoulder stiffness in 1(3.33%) patient and Delayed union in 1 (3.33%) patient. There is no malunion and non-union in this group. Case The goal of fracture management is restoration of physiological function at the earliest. Conservative treatment of humeral shaft fractures represents an effective method of fracture management and has sustained critical evolution throughout the literature. However, the incidence of non-union, malunion, residual angulation, limb length inequality and significant loss of function was shown to be high with non-operative management.
Operative treatment is proven to have greater strength, with improved functional outcome and earlier return to work at 6 weeks.
Surgical intervention includes closed reduction and internal fixation by humerus interlocking nail, open reduction and internal fixation by narrow DCP or LCP and Minimally invasive percutaneous plate osteosynthesis. As the gold standard method for the treatment of humerus shaft fracture is open reduction and internal fixation with a plate and screws is well recognised.
It has been reported that humeral shaft fractures can be successfully treated with minimally invasive percutaneous plate osteosynthesis (MIPPO). This technique has advantages of less soft tissue dissection and avoids the need to expose the radial nerve; thus, there is also low risk of iatrogenic radial nerve palsies and deep infection.

(1) Age and Gender:
In our study average age of patients is 33.86(range 18-60).
In study by M Shantharam Shetty et al. 26

(3)Mode of Injury:
In our study, out of 30 patients 17 (56.66%) sustained injury due to road traffic accident, 02 (6.66%) sustained injury following assault and 11(36.66%) sustained injury due to fall. Showing that road traffic accident is most common cause of fracture shaft humerus.
In study by M Shantharam Shetty et al. 26 26(81.2%) cases sustained road traffic accident (4) Fracture pattern: The fracture pattern was classified on AO Classification for fracture of shaft humerus. In our study we had 26 (86.66%) cases of AO12A type fracture in which 2(6.66%) cases of A1 type, 11(36.66%) cases of A2 type and 13(43.33%) cases of A3 type. 3(10%) cases of AO12B type fracture in which 3(10%) cases of B2 type. 1 (3.33%) of AO12C3 fracture type. So we have most common AO12A2 and A3 type of fracture pattern.
In study by M Shantharam Shetty et al. 26 there were 8 cases of C2 type; 5 cases of C1 and A2 type ; 4 cases of B2 type ; 3 cases of B3,B1and A1 type; and one case of A3 type of fracture.

(5) Trauma to surgery interval:
In our study out of 30 cases 17 (56.6%) case were operated within 3 days of trauma. 09(30%) cases were operated in between 3 to 7 days of trauma. 04(13.4%) cases were operated in between 7 to 14 days of trauma.

(6) Amount of Blood Loss during surgery:
In our study average blood loss during surgery for MIPPO technique is 114 ml.

(7) Duration of Surgery:
In Our study 30 cases of fracture shaft humerus studied with MIPPO. Operative time for 20 cases was between 30-60 minutes, 10 cases took 61-90 minutes. The average operative time was 60 minutes.
In study by M Shantharam Shetty et al. 26 the mean surgical time was 91.5 minutes (range 70-120 min).

(8) Duration Of Union:
In our study average time of union was 11.73 ±3.53 week ranging from 08 to 29 weeks. There was no case of nonunion. 1 patient had delayed union.
M Shantharam Shetty et al. 26 studied 32 patients of shaft humerus fracture operated with MIPPO ,in this study average time of union is 12.9 weeks (range: 10-20 weeks).

Outcome and Result:
In our study 30 cases of diaphyseal humerus fractures treated with MIPPO. Result is based on assessment of radiological union and functional outcome using UCLA and MAYO scoring. Average time of union was 11.73 ±3.53 weeks ranging from 08 to 29 weeks. There was no case of non-union. 1 patient had delayed union. We observed Excellent result in 22(73.33%) cases, Good in 07(23.33%) cases, and Fair in 01(3.33%) cases. No Poor outcome was seen. Average of UCLA Shoulder Score was 33.3±3.22 and of MAYO Elbow Score was 97.33±6.12.
In the study of M Shantharam Shetty et al. 26 , 27 cases (84.3%) had excellent outcome and 5 cases (15.6%) had good shoulder function on the UCLA score. With regard to elbow function, 26 cases (81.2%) had excellent outcome, 5 cases (15.6%) had good outcome, and 1 case (3.1%) (who also had an associated olecrenon fracture that was fixed with tension band wiring) had fair outcome.
In the study of Zhiquan An et al. 17 the functional outcomes assessed by UCLA end-result score and Mayo elbow performance score systems in the affected shoulder and elbow in the two groups were also consistent.

Complications:
We had 3(10%) patients with complication which includes superficial infection in 1(3.33%) patient which get resolved after culture specific antibiotics, Shoulder stiffness in 1(3.33%) patient and delayed union in 1 (3.33%) patient which get united in 29 weeks. There was no malunion and non-union.
In 1 patient during surgery MIPPO was converted to ORIF surgery because there is unseen long splinter of fracture which was excluded from the study.
M Shantharam Shetty et al. 26 had two cases with postoperative sensory blunting over the lateral half of the forearm due to injury to musculocutaneous nerve, but this recovered within 3 months of surgery without any intervention.
Zhiquan An et al. 17 found One case (6.3%) of delayed union occurred in group B which resulted from loosening of the screws in the proximal end of the plate. The patient was treated non-operatively and the fracture united 17 months after operation. There was no incidence of infection or implant failures in either group. All five iatrogenic radial nerve palsies spontaneously recovered with mean onset time of 22.4 weeks (range 12-52 weeks) without any surgical intervention. The implant was removed in five cases in group A and three cases in group B without any complications.

Limitation Of The Study:
The only limitation of the study was small sample size and less time for long term follow up.

Conclusion:
Out of various operative methods available today minimally invasive percutaneous plate osteosynthesis has showed many promising result of our study regarding management of diaphyseal humerus fracture with minimally invasive percutaneous plate osteosynthesis versus open reduction and internal fixation with the available literature.
Various operative methods are available today's for diaphyseal humerus fractures with variable rate of complication and union rate. Our results of management of these fractures with minimally invasive percutaneous plate osteosynthesis have been evaluated and compared with available literature.
We treated 30 cases in our study with minimally invasive percutaneous plate osteosynthesis (MIPPO) technique and found a rapid healing by secondary fracture union with few complications and hence achieving strong bone union across the fracture site due to inherent benefits of less tissue damage and minimal disturbance of fracture site biology.
In this study union rate was significantly higher and faster with minimal complications, less blood loss and less duration of surgery, it is cosmetically acceptable for the patients, but this technique is associated with radiation exposure, on other hand it requires skilled hands. As the procedure involves meticulous soft tissue handling and minimally exposure the procedure is considered technically demanding and a longer learning curve is required.  (6):520-6.