Adopting lateralization techniques in reverse shoulder arthroplasty

Shoulder joint replacement surgery has revolutionized the treatment options for patients with various etiologies affecting the shoulder. Furthermore, the technique of reverse shoulder arthroplasty (RSA) emerged as a game changer for patients that could not be fitted with traditional implant designs due to abnormal anatomical issues or muscle function instability. For years, the Grammont concept using a medialized approach provided relief to patients and excellent survival rates; however, its drawbacks have paved the way for a more lateralized approach. Here, Markus Scheibel (Chief Physician of the Shoulder and Elbow Surgery Department at Schulthess Clinic Zurich, Switzerland and visiting professor at Charité—University Medicine, Berlin, Germany) and Jan-Philipp Imiolczyk (assistant orthopedic trauma surgeon at Charité—University Medicine, Berlin, Germany) explain the concept and practice of lateralization and the current data on its outcomes and complications.

Markus Scheibel

AO Recon Shoulder Curriculum
Schulthess Clinic
Zurich, Switzerland

Jan-Philipp Imiolcyk

Jan-Philipp Imiolczyk

Charité—University Medicine
Berlin, Germany

Concept transition: Why shift from the classic Grammont concept?

Although first designs for shoulder arthroplasty have been in use since the 1970s, it was not until the late 1980s when Paul Grammont (Dijon, France) published his concept with a hemisphere directly attached to the glenoid surface. This design provided reliable, good clinical results with relatively low initial complication rates compared to the prosthesis used in the past. It was based on a medialized and distalized approach for RSA [1], with survivorship of about 90% at long-term follow-ups of 8–10 years [2]. The approach followed four main principles (summarized by Werthel et al [3]):

  1. Medialization of the joint center of rotation (JCOR) on the glenoid and the humerus with a straight stem and a 155° neck-shaft angle (NSA), which aims to increase the lever arm of the deltoid in active elevation and abduction
  2. Positioning the JCOR at the bone-implant interface minimizes shear forces on the glenoid component
  3. Distalization of the humerus, which helps to recruit more fibers of the anterior and posterior deltoid to act as abductors
  4. A semi-constrained configuration to provide static stability and a stable fulcrum

Despite the success of this approach, especially in cuff-deficient shoulders, its design has been reported to have several drawbacks. One of the main complications associated with RSA is prothesis instability; with 38% of patients undergoing revision surgery after a Grammont design RSA [4], two key factors for implant stability are the correct restoration of deltoid length and lateralization, as this provides sufficient tensioning of the soft tissues [5]. Moreover, a high number of patients undergoing Grammont design RSA suffer from scapular notching, as well as limited range of passive internal rotation and in particular no improvement in active external rotation capacity, and loss of normal shoulder contour [6, 7]. Notching is not just a radiographic phenomenon but has been shown to be progressive over time. One study analyzed notching in a Grammont design RSA and showed the notch incidence as a function increased from 58% occurring in the first 2–3 years after surgery to 87% at 6–10 years; however, in some cases, no notching was reported or notches stabilized rapidly after their appearance [8]. Overall, the study found the incidence of notching in 68% of cases with a mean follow-up of 51 months and a range of 50–96% at the 31–84 months follow-up. The study also found that the more active patients had a higher rate of notch incidence as well as original diagnosis of cuff tear arthroplasty (71%) and osteoarthritis (OA) (47%) with cuff deficiency influencing the incidence of notching [8]. When comparing cemented and uncemented components of the Grammont RSA over a mean 9.6-year follow-up, Melis et al [9] found scapular notching in 88% of shoulders, which was associated with the superolateral approach. Furthermore, they also found glenoid radiolucency, bony scapular spur, subsidence of the stem, and humeral radiolucency in three and four zones in cemented and one and two zones in uncemented components, with more signs of radiological stress shielding and resorption in uncemented components [9]. Attention should be paid when classifying notching on x-rays because the positioning and view of the x-ray when grading the notching are essential. It is clear, though, that scapular notching in the Grammont design is a complication that should be avoided. So, how have surgeons tried to compensate for these drawbacks that occur in the Grammont concept?

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  • The arrival of lateralization
  • Glenoid-sided lateralization
  • Humeral-sided lateralization
  • Global bipolar lateralization
  • Proposed technique: What works for us?
  • Is lateralized reverse shoulder arthroplasty performing?
  • Future perspectives
  • Conclusion

Part 2 | Mixed reality

Part 3 | Preventing infection

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Contributing experts

This series of articles was created with the support of the following specialists (in alphabetical order):
Ashish Gupta

Ashish Gupta

Queensland Orthopedic Clinic
Brisbane, Australia

Simon Lambert

Simon Lambert

AO Recon Shoulder Curriculum Taskforce
University College London Hospital
London, United Kingdom

Markus Scheibel

AO Recon Shoulder Curriculum Taskforce
Schulthess Clinic
Zurich, Switzerland

Jan-Philipp Imiolcyk

Jan-Philipp Imiolczyk

Charité—University Medicine
Berlin, Germany

This article was written by Laura Kehoe, AO Innovation Translation Center, Clinical Science, Switzerland.


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