Physiotherapy for A Climber's Scapholunate Injury: A Case Report Part II
We discuss the bio and pathomechanics of the scapholunate ligament plus climbing related protocols to optimize rehabilitation.
Case Report
We are now ~6-7 weeks post injury to the scapholunate ligament (SLL), the lunotriquetral ligament (LTL), and the dorsal radioulnar joint (DRUJ). Since our last post, our climber has moved on from isometric exercises and has begun isotonic exercises and loading her hand through range. In this post, we will cover the complex biomechanics of the SLL and how it affects climbing. A quick note, you might notice that focus on rehabilitation has been on the SLL. That’s because 1) there is not a lot of literature on the LTL and rehabilitation and 2) the SLL is the biomechanical cornerstone of the hand! So prioritizing the SLL in therapy will ultimately have positive spill-over effects onto the LTL and the DRUJ.
Biomechanics of the SLL
As of 2022 we have ~7 different theories in how the wrist bones above the radius and ulna work. Most have used cadaver and X-ray images for their theories and one recent study used MRI on live volunteers. The reason why there is no unifying theory is that each of the eight carpal bones has unique shapes, resulting in different force transmissions between each other and the metacarpals and radius/ulna. This makes it likely the most complicated joint structure in the body. You might also be surprised to find that there are no muscle/tendon attachments to the scaphoid. Only the transverse carpal ligament, the proximal radius, lunate/capitate (medial), and the distal trapezoid/trapezius as the bony articulations! So if no muscles attach to the scaphoid and no
So, few truths exist about the wrist mainly:
1) The carpal bones must be rigid yet allow for a variety of movements simultaneously and another
2) The carpal bones absorb and transmit forces from the radius/ulna and from the distal fingers. Eschweiler et al. 2022 reports that the 1954 Link Theory suggests that the scaphoid is key to stabilizing forces from the proximal radius and distal forces from the capitate. Not having the oblique, cradle shape of the scaphoid would lead to the bones shifting as seen in (B). The scaphoid leads to the scenario (C).
Let’s break down how this keystone bone works.
Kinematics of the SLL
Due to the odd oblique orientation and shape of the scaphoid, the hand can move into what scientists and surgeons call the “dart-thrower’s motion” (DTM). This motion is not just for playing darts, but movement from cocking the wrist back to throwing forward is what allows humans to twist a jar open, drink from a glass, and rock climb. Just a few moves the DTM allows a climber to do: throw to a side pull, rotate from a hold to an undercling, and gaston onto a super small jib. Remember the DTM integrates both radial & ulnar deviation, slight pronation/supination and wrist flexion/extension.
Kinetics of the SLL
When forces are loaded axially on the wrist, ~50% is absorbed by the radioscaphoid joint and 35% of the radiolunate joint. Since the scaphoid and its ligaments are wedged in between the radius and the lunate, you could say the scaphoid and its ligaments absorb up to 85% of the forces.
As described earlier, when the wrist is flexing and extending the scapholunate joint twists (pronates/supinates) a lot more. This gap, combined with the large forces from palmar ligaments, the radiolunate and lunotriquetral ligaments, leads to the scaphoid and its ligament absorbing the majority of the forces on the wrist. Again this force funnel occurs due to the unique C/boat shape and its place as the sole linking bone between the carpal bones (the radius/ulna and the distal carpal bones (trapezium/trapezoid and capitate).
Pathomechanics and the SLL
Lewis and Osterman 2001 report that when a climber falls with an outstretched arm or persistently loads the wrist in flexion and extension the scaphoid and its ligament become overloaded. Swedish hand surgeon, Jonny Andersen in 2017 writes that damage to the SLL leads the scaphoid bone doing the following:
1. Flexing forward towards the palm
2. The lunate moves backwards because it is fixed to the triquetrum.
In the case of a LTL injury the opposite scenario happens (the scaphoid moves back and the lunate moves forward). This is called scaphoid dorsal intercalated segment instability (DISI) and lunate volar intercalated segment instability (VISI). Now our climber was diagnosed with BOTH but based on her subjective description of moving her hand and the lunate sliding backwards, it seems that the SLL is currently more injured than the LTL.
It’s been ~6 weeks so the ligaments are healing but they are still relatively lax. How do we know this and how do we progress the rehab process?
We know that this is the case because of:
1. Pain generated in positions of tension for the SLL and LTL
2. Decreased strength due to the lack of static stability provided by the ligaments.
You can see the trajectory of improvement in grip strength of the left hand. In the first 4 weeks, our team was hesitant to let our climber resume her rehab in the gym. This was because the left hand’s grip strength was around 20% of her right hand.
From the Clinic to the Gym
The studies above tell us that loading the wrist in a neutral or extended position rolls it greatly and twisting the wrist side to side pushes the scaphoid forwards and backward.
In climbing terms, this means that:
1. Compression, undercling, gaston, and mantling likely exert the largest forces to the scaphoid
2. Dynamic moves where your hand may need to react to different positions may exert a sudden and large force on the scaphoid (dynos, lache, dead-point…etc)
3. Locking off on edges, slopers, and pinches with a neutral wrist position may exert less force on the scaphoid.
There currently is no biomechanical evidence on different holds and their respective forces on the scaphoid (Ferrer-Uris 2023). However a study by Mukaiyama et al 2022 revealed that during a pinch grip the force significantly increases towards the scaphoid and radial side of the hand. Let’s see if this matches with our climber.
Based on this graph we can likely say that pinches and gastons confirm the large biomechanical forces on the scaphoid and SLL leading to insufficient absorption strength and pain. The focus on rehab, then, would be the focus on the next 2 weeks on edges and maybe side pulls as they cause less pain and load the wrist to get stronger. This makes sense because the wrist position in these holds is likely neutral, neither rolling nor bending allow the linking of the scaphoid and carpal bones to be statically stable while transmitting force.
Optimization of physiotherapy occurs when this load management curve is applied to the specifics of the sport. In this case we need to ensure our climber is reaching the minimum effective stress to induce improvements to her tendons and secondary stabilizers around her SLL and LTL. Since we have solid data on what climbing features are generating pain and not we can tailor a climbing program to her specific biomechanical needs.
Given the information provided above, this is a general progression of our rehabilitation progress currently.
REHAB STAGE II: Isotonics
Purpose: Axially load the scaphoid through its Dart Thrower’s Motion (through its function range) and activate the proprioceptors/tendons/muscles for climbing
Frequency: Daily | Intensity: 2-3/10 pain | Type: Isotonics
Time: 10 reps x 3 sets| Avoid excessive pain and range of motion in wrist and thumb
REHAB STAGE II: Climbing Specific Isometrics on the Hangboard
Purpose: Re-train climbing specific strength
Frequency: 3 x week | Intensity: 3/pain | Type: Isometrics (12-14mm holds)
Time: 3 x 10 seconds on + 50 seconds rest | Volume: 2-3 sets
No Dead Hangs (feet on ground), focus on maintaining a neutral wrist
In part III of our case study we will reassess our climber at 8 weeks to see if we can progress her to begin climbing gaston, pinches and begin to introduce more dynamic movements.
References