Authors of section

Authors

Martin Jaeger, Frankie Leung, Wilson Li

Executive Editors

Peter Trafton

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MIO - Screw fixation

1. Principles

Indications

Impacted minimally displaced proximal humerus fractures, even though they involve the anatomical neck, have a relatively good prognosis. Due to the intact periosteum, they are often quite stable. Improved alignment can often be obtained, and stability provided with minimal fixation (eg, screws alone). This technique requires caution if there is osteoporosis or comminution.

Reduction with disimpaction may result in fracture instability. Some of these fractures may have questionable stability before reduction. To improve stability, an osteosynthesis might be considered.

Valgus impacted 3- and 4-part fractures and slightly displaced comminuted fractures with varus malalignment are particularly suitable for less invasive reduction and fixation. These are the most suitable procedures for patients with good bone quality.

Because fractures with varus deformity are less stable use caution when choosing screws alone for fixation.

Risk of avascular necrosis

Even minimally displaced anatomic neck fractures have a significant risk of avascular necrosis (AVN) of the humeral head. This risk is increased with extensive surgical exposure for open reduction and plate fixation.

With the blood supply already at risk, closed reduction and minimal internal fixation through very limited approaches is advisable.

2. Patient preparation and approach

Patient preparation

This procedure is normally performed with the patient in a beach chair position.

hemiarthroplasty

Safe zones for screw insertion

Inserting percutaneous instrumentation through the safe zones reduces the risk of damage to neurovascular structures.

mio screw fixation

3. Reduction

Manual reduction

In fractures with separate fragments of the proximal humerus reduction involves repositioning the humeral head, and also restoring the tuberosities to their proper location.

The medial periosteum (medial hinge) is not ruptured. Much of the remaining periosteum (especially laterally) may also be intact.

As a first step perform a closed reduction taking advantage of the intact soft-tissue sleeve (as with ligamentotaxis). Frequently, the displaced fragments will snap into position with this maneuver.

Valgus forces (abducting at the fracture) can be applied to the lateral aspect of the humeral shaft to correct the varus deformity and facilitate manual reduction.

As a first step perform a closed reduction taking advantage of the intact soft-tissue sleeve.

Periosteal elevator and/or bone hook

If closed reduction is unsuccessful, minimally invasive open reduction can be attempted through a small transdeltoid incision using appropriate instruments.

Periosteal elevators or punches can be used to disimpact and reposition fracture fragments.

If the reduction is not adequate, a similarly inserted bone hook may aid reduction of the tuberosities.

Protect the axillary nerve on the deep surface of the deltoid muscle, 6 cm below the acromion.

mio screw fixation

Adequate reduction

Adequate reduction has been achieved if the tuberosities come to lie laterally flush or slightly underneath the elevated humeral head.

Check reduction by image intensification.

Adequate reduction

4. Preliminary fixation

Temporarily fix the fracture with K-wires as illustrated in this case for a 4-part fracture. Place the K-wires so that they do not hinder subsequent screw insertion.

Temporarily fix the fracture with K-wires as illustrated in this case for a 4-part fracture.

5. Fixation

Fixation of the head fragment

Two or more percutaneously inserted screws linking the shaft fragment to the head fragment are inserted first.

Cannulated 3.5 mm lag screws (as illustrated), or non-cannulated small fragment lag screws are used according to the surgeon’s preference.

This illustration shows two screws inserted over guide wires.

Note: Washers may be advisable in poor bone stock. Generally, they are not preferable as they make the screw heads more prominent and may result in shoulder impingement.

Fixation of the head fragment

Fixation of the tuberosities

Remove K-wires and guide wires from the shaft.

Fixation of the head fragment is followed by insertion of screws in the greater and lesser tuberosity.

Again, in this case, screws are inserted over guide wires.

Fixation of the tuberosities

Completed osteosynthesis

The illustration shows the completed osteosynthesis.

Check the reduction and the length/position of the screws by image intensification.

Check the reduction and the length/position oft the screws by image intensification.

6. Final check of osteosynthesis

Using image intensification, carefully check for correct reduction and fixation (including proper implant position and length) at various arm positions. Ensure that screw tips are not intraarticular.

Carefully check for correct reduction and fixation (including proper implant position and length) at various arm positions.

Also obtain an axial view.

Also obtain an axial view.

In the beach chair position, the C-arm must be directed appropriately for orthogonal views. Position arm as necessary to confirm that reduction is satisfactory, fixation is stable, and no screw is in the joint.

In the beach chair position, the C-arm must be directed appropriately for orthogonal views.

7. Overview of rehabilitation

The shoulder is perhaps the most challenging joint to rehabilitate both postoperatively and after conservative treatment. Early passive motion according to pain tolerance can usually be started after the first postoperative day - even following major reconstruction or prosthetic replacement. The program of rehabilitation has to be adjusted to the ability and expectations of the patient and the quality and stability of the repair. Poor purchase of screws in osteoporotic bone, concern about soft-tissue healing (eg tendons or ligaments) or other special conditions (eg percutaneous cannulated screw fixation without tension-absorbing sutures) may enforce delay in beginning passive motion, often performed by a physiotherapist.

The full exercise program progresses to protected active and then self-assisted exercises. The stretching and strengthening phases follow. The ultimate goal is to regain strength and full function.

Postoperative physiotherapy must be carefully supervised. Some surgeons choose to manage their patient’s rehabilitation without a separate therapist, but still recognize the importance of carefully instructing and monitoring their patient’s recovery.

Activities of daily living can generally be resumed while avoiding certain stresses on the shoulder. Mild pain and some restriction of movement should not interfere with this. The more severe the initial displacement of a fracture, and the older the patient, the greater will be the likelihood of some residual loss of motion.

Progress of physiotherapy and callus formation should be monitored regularly. If weakness is greater than expected or fails to improve, the possibility of a nerve injury or a rotator cuff tear must be considered.

With regard to loss of motion, closed manipulation of the joint under anesthesia, may be indicated, once healing is sufficiently advanced. However, the danger of fixation loosening, or of a new fracture, especially in elderly patients, should be kept in mind. Arthroscopic lysis of adhesions or even open release and manipulation may be considered under certain circumstances, especially in younger individuals.

Progressive exercises

Mechanical support should be provided until the patient is sufficiently comfortable to begin shoulder use, and/or the fracture is sufficiently consolidated that displacement is unlikely.

Once these goals have been achieved, rehabilitative exercises can begin to restore range of motion, strength, and function.
The three phases of nonoperative treatment are thus:

  1. Immobilization
  2. Passive/assisted range of motion
  3. Progressive resistance exercises

Immobilization should be maintained as short as possible and as long as necessary. Usually, immobilization is recommended for 2-3 weeks, followed by gentle range of motion exercises. Resistance exercises can generally be started at 6 weeks. Isometric exercises may begin earlier, depending upon the injury and its repair. If greater or lesser tuberosity fractures have been repaired, it is important not to stress the rotator cuff muscles until the tendon insertions are securely healed.

nonoperative

Special considerations

Glenohumeral dislocation: Use of a sling or sling-and-swath device, at least intermittently, is more comfortable for patients who have had an associated glenohumeral dislocation. Particularly during sleep, this may help avoid a redislocation.

Weight bearing: Neither weight bearing nor heavy lifting are recommended for the injured limb until healing is secure.

Implant removal: Implant removal is generally not necessary unless loosening or impingement occurs. Implant removal can be combined with a shoulder arthrolysis, if necessary.

Shoulder rehabilitation protocol

Generally, shoulder rehabilitation protocols can be divided into three phases. Gentle range of motion can often begin early without stressing fixation or soft-tissue repair. Gentle assisted motion can frequently begin within a few weeks, the exact time and restriction depends on the injury and the patient. Resistance exercises to build strength and endurance should be delayed until bone and soft-tissue healing is secure. The schedule may need to be adjusted for each patient.

Phase 1 (approximately first 3 weeks)

  • Immobilization and/or support for 2-3 weeks
  • Pendulum exercises
  • Gently assisted motion
  • Avoid external rotation for first 6 weeks

Phase 2 (approximately weeks 3-9)

If there is clinical evidence of healing and fragments move as a unit, and no displacement is visible on the x-ray, then:

  • Active-assisted forward flexion and abduction
  • Gentle functional use week 3-6 (no abduction against resistance)
  • Gradually reduce assistance during motion from week 6 on

Phase 3 (approximately after week 9)

  • Add isotonic, concentric, and eccentric strengthening exercises
  • If there is bone healing but joint stiffness, then add passive stretching by physiotherapist