This patient underwent 3 shoulder surgeries prior to referral to us. The primary press fit hemi-arthroplasty for the proximal humerus fracture was the first surgery which was revised to a cemented hemi-arthroplasty due to loss of the version of the press fit prosthesis. The 3rd operation was done as an attempt to revise to a reverse shoulder replacement and a vascular injury resulted in abandoning the surgery. Subsequently the patient was referred to us for treatment. She had constant pain and very limited active forward flexion of the shoulder.
Below are the preoperative Grashey X-ray of the shoulder which demonstrates a high riding humeral head and prosthesis, failure of healing of the tuberosities, no signs of loosening of the implant, and thin cortices at the metaphyseal area of the proximal humerus. A CT scan shows good bone stock and no cavitation of the glenoid.
Revision to a reverse shoulder replacement was considered in this case as there was enough glenoid bone stock and the patient was older than 70 years of age. The main challenges of this surgery are outlined below:
1. Prior axillary artery repair, increase risk of repeat vascular injury as there is an altered surgical field from 3 prior surgeries
2. Although there is modularity of shoulder implants with the option to preserve the humeral stem and convert to a reverse total shoulder replacement, a high riding humeral prosthesis in combination with scar tissue from prior surgeries does not permit enough lengthening of the arm for conversion to a reverse.
3. Preservation of the humeral stem seems impossible in this case as it is necessary to displace the humeral head distally enough to accommodate an inferior placed glenosphere on the glenoid
4. Removal of a well fixed cemented humeral stem in the setting of osteopenia with thin bone cortices is one of the most challenging problems in shoulder revision surgery. There is a high risk for fracture.
Taking into consideration those challenges and being prepared for those complications we elected to proceed with conversion to a reverse total shoulder replacement. The steps for a conversion to a reverse are outlined below:
1. Careful approach to the shoulder using the previous deltopectoral approach
2. Removal of the prosthetic humeral head from the stem
3. Prior multiple cultures showed no signs of infection, however multiple cultures were obtained again
4. Osteotomes were used on the proximal collar to "debond" the prosthesis and avoid fracture of the tuberosities during the removal of the stem.
5. A vertical humeral uni-cortical osteotomy was performed with an oscillating saw. With a set of osteotomes that are placed vertically in the osteotomy site - within the osteotomy - gentle twisting opened the humeral envelope and increased the diameter of the canal by a few millimeters. Gentle repetition of this twisting created a visible gap between the cement mantle and the prosthesis. It is important to avoid distal extension of the osteotomy pass the tip of the humeral prosthesis as this creates a stress riser.
6. A bone impactor is placed on the collar of the prosthesis proximally and the stem was gently tapped which resulted in extraction of the prosthesis.
7. Cables were passed around the shaft of the humerus and a new press fit implant was selected by assessing the diameter of the cemented humeral canal with a straight reamer. A "tight fit" is enough for fixation as later closure of the osteotomy site with the cables will create a stable construct. Cement can be used at this stage if desired.
The remaining part of the case was a typical implantation of a reverse prosthesis.
Postoperative xray is shown below:
6 weeks after surgery there is healing of the osteotomy and no dislocation
