Minimally invasive plate osteosynthesis (MIPO) for scapular fractures

Abstract

Objective: Presentation of a minimally invasive surgical approach for the treatment of scapular fractures and the clinical outcome using this technique.

Indications: Displaced extra-articular fractures of the scapula body and glenoid neck (AO 14B and 14F) and simple intra-articular fractures of the glenoid.

Contraindications: Complex intra-articular fractures and isolated fractures of the coracoid base.

Surgical technique: Make a straight or slightly curved incision along the lateral margin of the scapula leaving the deltoid fascia intact. Identify the interval between the teres minor muscle and infraspinatus to visualize the lateral column, whilst retracting the deltoid to visualize the glenoid neck. Reduce and align the fracture using direct and indirect reduction tools. A second window on the medial border of the scapula can be made to aid reduction and/or to augment stability. Small (2.0-2.7 mm) plates in a 90° configuration on the lateral border and, if required, on the medial border are used. Intra-operative imaging confirms adequate reduction and extra-articular screw placement.

Postoperative management: Direct postoperative free functional nonweight-bearing rehabilitation limited to 90° abduction for the first 6 weeks. Sling for comfort. Free range of motion and permissive weight-bearing after 6 weeks.

Results: We collected data from 35 patients treated with minimally invasive plate osteosynthesis (MIPO) between 2011 and 2021. Average age was 53 ± 15.1 years (range 21-71 years); 17 had a type B and 18 a type F fracture according the AO classification. All patients suffered concomitant injuries of which thoracic (n = 33) and upper extremity (n = 25) injuries were most common. Double plating of the lateral border (n = 30) was most commonly performed as described in the surgical technique section. One patient underwent an additional osteosynthesis 3 months after initial surgery due to pain and lack of radiological signs of healing of a fracture extension into the spine of the scapula. In the same patient, the plate on the spine of scapula was later removed due to plate irritation. In 2 patients postoperative images showed a screw protruding into the glenohumeral joint requiring revision surgery. After standardisation of intra-operative imaging following these two cases, intra-articular screw placement did not occur anymore. No patient suffered from iatrogenic nerve injury and none developed a wound infection.

Keywords: Deltoid sparing; MIPO; Minimally invasive surgical procedures; Scapula fracture.

Fig. 1

a Positioning of the patient and C‑arm. b Patient after draping

Fig. 2

A straight incision along the lateral margin of the scapula or a slightly curved more cosmetic incision directed towards the axilla is performed. A full thickness skin and subcutaneous flap is created leaving the superficial deltoid fascia intact

Fig. 3

The deltoid margin, infraspinatus and teres minor are identified

Fig. 4

The deltoid is retracted cranially (abduction of the shoulder with additional padding may also help removing the deltoid muscle out of the operating field) and the interval between teres minor and infraspinatus is identified. This interval is frequently not well defined. A helpful anatomical landmark is the fact that the infraspinatus muscle usually has diamond shaped muscle fibres, whilst the teres minor has linear fibres. Furthermore the interval can also be found by palpating the lateral border of the scapula: infraspinatus lies superior and the teres minor inferior to the lateral scapular border. Failure to identify the correct interval might cause damage to the axial nerve that runs between the teres minor and major laterally

Fig. 5

The ascending branch of the circumflex scapular artery frequently runs across the lateral margin of the scapula in the interval between teres minor and infraspinatus. This artery should be ligated or cauterized to prevent troublesome bleeding

Fig. 6

a After identification of the interval between the infraspinatus and teres minor the lateral margin of the scapula is identified. The fracture zone is exposed and cleared. b Reduction and alignment of the lateral margin is achieved using two reduction forceps on either side of the fracture. To maintain reduction, a 2.0 mm (or 2.7 mm) plate may be positioned and fixed on the lateral edge of the scapula (leaving space for a 2.7 mm plate on the surface of the scapular body which will ultimately provide the required stability). An alternative for maintaining reduction is the use of two Schanz screws (2.5 mm) and connecting them with a rod from the mini external fixator set

Fig. 7

a The 2.7 mm plate should be precontoured keeping the glenopolar angle (30–40°) in mind. The plate is positioned on the dorsal aspect, along the lateral border of the scapula. Preliminary fixation with K‑wires is advisable. b It is important in this phase to obtain adequate intraoperative radiographs with a free projection of the joint glenohumeral joint to exclude intra-articular positioning of the most cranial K‑wire. The direction of the cranial K‑wire may be used as a reference when placing the screws in the cranial part (near the glenohumeral joint) of the plate. At the end of the procedure multidirectional intra-operative radiographs should be obtained

Fig. 8

a In case of a comminuted lateral border in which rigid fixation is not possible or medial displacement (> 1 cm), an additional incision over the medial margin is performed. The medial incision and precedent reduction of the the margo medialis is made neutralizing the medial–lateral displacement of the scapular body fragment and adding reduction. Addressing the medial side first might also be beneficial in cases of severe comminution of the lateral margin where no good reference for reduction can be obtained. If required, additional windows can be made over the spina scapulae, in case of fractures extending to this part of the scapula. b The intra-operative images show fracture reduction using four 2.7 mm plates

Fig. 9

Number of osteosyntheses for scapula fractures on a yearly basis