Orthopaedics Unplugged

Mayfield Classification of Carpal Instability:
Stage 1: Scapho-lunate dissociation (Terry Thomas sign)
Stage 2: Perilunate dislocation
Stage 3: Midcarpal dislocation
Stage 4: Lunate dislocation (spilled teacup sign)

Significance of Watershed Line of Distal Radius:
- It is a surgical landmark lying distal to pronator quadratus and used for positioning a volar locking plate.
- It is 2 mm proximal to ulnar side joint line and 10-15 mm proximal to radial side joint line.
- Plate positioned distal to this line will lead to abrasion and subsequent tear of flexor tendons, most commonly being FPL.

Various Lateral-column shortening procedures used in Neglected or Recurrent CTEV:
1. Litchtblau procedure
2. Goldner procedure
3. Enucleation of Cuboid
4. Dilwyn-Evans procedure

Post-operative Radiographic Assessment of Hip Arthroplasty:
1. Leg length
2. Horizontal centre of rotation
3. Vertical centre of rotation
4. Acetabular Inclination
5. Femoral stem positioning
6. Acetabular anteversion
7. Cement Mantle
Note- every parameter is assessed on AP view except for acetabular anteversion which is measured on a lateral radiograph.

Dorsal Horizon View:

- This newly described dorsal tangential view provides a more complete visualization of the triangular distal radius cortex, particularly at Lister’s tubercle, allowing for a more accurate assessment of screw protrusion.

- Obtained by supinating the forearm, hyperflexing the wrist, and aiming the beam of the image intensifier along the long axis of the radius.

PCL Balancing during Fixed bearing Cruciate Retaining TKR
POLO test: Pull-out Lift-off test
Pull-out test: Used to assess the knee for flexion laxity. With the trial components in place, the knee is flexed 90 degrees. The surgeon then tries to pull out the tibial component from underneath the femur. If the knee fails the pull-out test, thicker inserts are tried until pull-out no longer is possible.

Lift-off Test: With the same trial components in place, the knee is flexed between 80 and 100 degrees. If the PCL is too tight, it will pull the femur posteriorly on the tibia where the posterior condyles impinge on the posterior lip of the tibial insert, pushing it down in back with lift-off in front.
Causes of lift-off other than tight PCL:
-If the lift-off test is performed with the patella everted and the knee has a tight quadriceps mechanism.
-Failure to clear the posterior femur of uncapped bone or retained osteophytes.