Background

Rotator Cuff Arthropathy for Reverse TSR

 

Indications

 

1.  RC arthropathy / > 70 / low functional demand

 

2.  Revision TSR

 

3.  Failed Hemiarthoplasty in proximal humerus fracture

 

Design

 

Reverse TSR Xray

 

In rotator cuff dysfunction

- humeral head superior causing early failure of conventional TSR

 

Professor Paul Grammont

- convex articular surface to glenoid

- concave surface humerus

- shifts centre of rotation medially and distally to glenoid

- improves lever arm of deltoid

 

Limitations of conventional TSR

 

1.  Inability to manage GH translation

 

Fully conforming surfaces

- humeral and glenoid components same radius curvature

- rim loading must occur with any translation

- rocking horse mechanism

 

Non conforming surfaces

- glenoid radius curvature > humeral head

- diminishes contact area

- increases local contact pressure

- risk poly failure

 

2.  Limitation of fixation of poly to glenoid

- subject to shear forces             

 

3.  Limitations of stability

 

Anterior instability

- defects SSC or anterior capsule / glenoid

 

Posterior instability

- posterior glenoid deficiency / dysplasia

- deficient posterior capsule or labrum

 

Superior instability

- deficient SS or CA ligament / acromion

- laxity of deltoid means it cannot function

- pseudoparalysis from antero-superior escape

 

4.  Deltoid dysfunction

- unable to raise / lower / medialise centre of rotation to compensate for deltoid dysfunction

- without risking loosening and failure of the glenoid component

 

Features of Reverse TSR  

 

1.  GH translation

- does not permit GH translation

- due to conforming concavity of humeral component

- full surface contact maintained during range

- nil rim loading

 

2.  Glenoid fixation

- metaglene fixed by locking and non locking screws along with a central press fit HA coated peg

- metal glenosphere fixed by press taper

- no poly to metal fixation issue

- medialisation of centre of rotation decreases the lever arm of forces

- reduces the moments that challenge fixation

 

Reverse TSR AP BiometReverse TSR Lateral

 

3.  Intrinsic stability

- nature of design has increased intrinsic stability

- humeral socket  forms an angle of 155o with humeral shaft

- deltoid force acts to stabilise the joint

- less dependence on soft tissue and CA arch

 

4.  Deltoid dysfunction

- able to lower or lateralise COR

- inherent stability allows prosthesis to work even if only part of deltoid functions

  

Results

 

ROM

 

Cuff et al JBJS Am 2008

- 96 patients with minimum 2 years follow up

- abduction increased from 61 to 110o

- flexion 60 to 120o

- ER from 13 to 30o

 

Complications

 

Wall et al JBJS Am 2007

- 191 shoulders followed for a minimum two years

- worst results in post traumatic arthritis and revision TSR

- 15 cases of dislocation

- 8 cases of infection

 

Survival

 

Guery et al JBJS Am 2006

- calculated 10 year survival rate of 90%

- noted than Constant shoulder scores deteriorated over time

- 60% 10 year survival with Constant score < 30 as an end point