Ulnar Nerve Entrapment

Left ulnar nerve

My patient who is a Team Singapore cyclist came in with a case of ulnar nerve entrapment on Friday. Ulnar nerve entrapment* is the second most common nerve condition happening in the upper limb after carpal tunnel syndrome.

The ulnar nerve arises from the brachial plexus at C8-T1 and travels down the inner part of the upper arm through the arcade of struthers (pictured below).

At the elbow, the ulnar nerve travels just behind the bony part on the inner part of the elbow. This is also know as the "funny bone" when you can get sensations of pins and needles after bumping the area. 

Picture by Conor Jones

As the ulnar nerve crosses the elbow, it passes through a bony tunnel and up to 2 other potential points for blockage making it vulnerable to pressure or stretching. Prolonged periods of sleeping with the elbow bent can also cause over stretching of the nerve. My patient hurt her ulnar nerve after riding for a few hours in a new position after changing her handlebars. Riding for a few hours on bumpy roads did not help. She had also fractured both her clavicles (R followed by L in the last few months). This is also known as the cubital tunnel syndrome.

The ulnar nerve supplies the sensation and muscles to the 5th and half the ring finger. Symptoms are related to degree of irritation of the nerve. They start off intermittent in nature and may only come on at night after the nerve has been stretched for a longer time. 

Pins and needles, aching or tingling in the little and/ or ring finger will be the common symptoms. This is what my patient felt. If the irritation persists, the symptoms may become constant and progress to numbness in the 5th and/ or ring finger and ultimately weakness in the hand.

As the ulnar nerve exits the bony tunnel, it goes into the flexor carpi ulnaris muscle. Follwing that at the wrist, it travels superficially to the flexor retinaculum and passes into Guyon's canal.  

R wrist

Guyon's canal is formed by 4 borders (pictured above). The roof is the palmar carpal ligament, the floor being the transverse carpal ligament, the ulnar (inner) border is the pisiform and the radial (outer) border is hook of hamate.  If the nerve is irritated at the wrist it is known as Guyon's canal syndrome.

Picture from Medical Art Library

The flexor carpi ulnaris and inner half of flexor digitorum profundus muscles are innervated by the ulnar nerve and the hypothenar muscles (pictured above).

Knowing the exact site of nerve irritation during an accurate clinical examination will help decide what needs to be done for treatment. Some doctors send their patients to do a nerve conduction test, but I personally find that an upper limb tension test (with radial nerve bias) done correctly does a much better job. Others may do ultrasound imaging to help diagnosis. Do not confuse it with thoracic outlet syndrome.

Just remember not to have a steroid/ cortisone injection.

*Ulnar nerve entrapments are commonly seen in cyclists, golfers, weightlifters and construction workers.

References

Kong G, Brutus JP, Vo TT et al (2023). The Prevalence Of Double- And Multiple Crush Syndromes In Patients Surgically Treated For Peripheral Nerve Compression In The Upper Limb. Hand Surg Rehabil. 42(6): 475-481. DOI: 10.1016/j.hansur.2023.09.002

Raut P, Jones N, Raad M et al (2022). Common Peripheral Nerve Entrapments In The Upper Limb. Br J Hosp Med. 83(10): 1-11. DOI: 10.12968/hmed.2022.011

Have a look at this ulnar nerve video.

Does Strength Training Help Runners Prevent Injuries?

Last week I wrote about how we have been told for years that the key to staying pain and injury free can be found somewhere close to your belly button. That got most people obsessed with strengthening their core or abdominal muscles. Which you know by now that it is not totally true.

Likewise many runners also believe that strength training like squats, deadlifts and other power lifting staples can make you faster, more powerful, more efficient and less injury prone.

Ever wonder what sort of strength training do top runners do? Blagrove et al (2020) did a survey of 667 distance runners (local to internationally competitive) about their strength and conditioning exercises. Most common was stretching (86.2 percent), core training (70.2 percent),  weight training (62.5 percent) and plyometric training (35.1 percent).

What was most interesting was the motivation these runners reported for the strength and conditioning routines. There were 2 main answers. Reducing injury risk (63.1 percent) and improving performance (53.8 percent). There was no relationship found between strength and conditioning training and injury history in runners. The key predictor of injury was training volume. The more you ran, the more likely you would get injured.

 In another systematic review published last month, Blagrove and colleagues (Wu et al, 2024) found that strength and conditioning does not appear to reduce the risk and rate of running related injuries (RRI). Please bear in mind that Richard Blagrove has authored a book Strength And Conditioning For Endurance Running and worked with many elite runners on their strength routines in case you think he is against strength training.

Their systematic review consist of 9 articles with 1,904 runners. Exercises done include lunges, squats, plyometric hops/ jumps, core routines, foot strengthening etc. Given the wide variety of of regimens, there was NO significant benefit for the exercise groups compared to the control group in injury risk (runners who got injured during the studies) or injury rate (how many injuries they suffered for a given amount of running).

For now that is the state and level of evidence we have with regards to strength and conditioning exercises preventing RRI. Strange that this approach (strength and conditioning) has robust evidence that it works in soocer, but not in running.

What was most interesting is that 3 of the studies that produced the lowest injury risk also happened to be the 3 studies where the exercise routines was supervised rather than assigned to be performed at home. Research shows that people tend to get bigger gains when they have a spotter or trainer looking on. Similarly, runners tend to run their intervals faster and more consistently when the coach is standing on the track with a stopwatch in hand. It could also be the only way to ensure people actually do the strength and conditioning exercises. 

I can remember many patients who come for a follow up visit claiming they have done their exercises diligently but cannot do it when asked to demonstrate it. A strengthening exercise can only work if you actually do it and have done it correctly.

Take home message? If the study (Wu et al, 2024) is true, strength training or other forms of exercise may not lower your risk of getting injured while running. Even though the logic is sound and evidence from other sports is positive. However, there is very good evidence that strength training improves running economy and boosts long term health. It would be nice to get injury prevention as an added bonus but it still sounds like a good deal to me. So I will still strength train.

Researchers need to have more robust studies that include supervised interventions to investigate further.

References

Blagrove RC, Brown N, Howatson G et al (2020). Strength And Conditioning Habits Of Competitive Distance Runners. J Stren Cond Res. 349(5): 1392-1399. DOI: 10.1519/JSC.0000000000002261.

Wu H, Brooke-Wavell K, Fong DTP et al (2024). Do Exercise-Based Prevention Programs Reduce Injury In Endurance Runners? A Systematic Review And Meta-Analysis. Sports Med. DOI: 10.1007/s40279-024-01993-7.

Weak Core, Tight Hamstrings And Weak Glutes?

Hope you have been enjoying your Chinese New Year break!

A patient came in this past week with low back pain and was told by another physiotherapist that she had a weak core, tight hamstrings and weak glutes and that was why her back hurts.

Now, I do not agree with that. Actually studies show that back extensor strength is more important than  flexor (abdominal) strength when it comes to low back pain (Lee et al, 1999).

Like I wrote previously, the idea for the need of a strong core was first introduced by Paul Hodges (Hodges and Richardson, 1998) when he published his article on the Transverse Abdominis (TA) muscle. His research compared the timing of TA and Multifidus in people with low back pain (LBP) for 18 months or more against healthy subjects with no LBP.

Hodges suggested that the TA was likely to be the main cause of LBP as it is the most important and deepest muscle in the abdomen. It looks and works like a corset to stabilise the back.

This article made the allied healthcare/ fitness industry conclude that the TA was a trunk stabilising muscle that was very important to strengthen for those with LBP. Patients who had LBP had weaknesses in their TA which led to instability in the spine.

Similarly with 'tight' hamstrings (Halbertsma et al 2001) and weak glutes. This female patient of mine can deadlift 90 kg. Her glutes are not weak nor are her hamstrings tight. 

You can put all those myths to rest. Your low back pain is not caused by a weak core, tight hamstrings nor weak glutes. Stengthening your back extensors will be a much better option than the previously mentioned.

References

Halbertsma JP, Goeken LN, Hof AL et al (2001). Extensibility And Stiffness Of The Hamstrings in Patients With Nonspecific Low Back Pain. Arch Phys Med Reh. 82(2): 232-238. DOI: 10.1053/apmr.2001.19876

Hodges PA and Richardson CA (1998). Delayed Postural Contraction Of Transversus Abdominis In Low Back Pain Associated With Movement Of The Lower Limb. J Sp Disorders. 11(1): 46-56.

Lee JH, Hoshino Y, Nakamura K et al (1999). Trunk Muscle Weakness As A Risk Factor For Low Back Pain. A 5-year Prospective Study. Spine (Phila Pa 1976). 24(1): 54-57. DOI 10.1097/00007632-199901010-00013

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Tread Lightly To Avoid Knee Pain

Picture from Functional Path Training

My first running coach once gave my cross country team mates and I this advice. Land 'softly' while running. "Imagine you're running on egg shells and you do not want to break them further". A few of the boys commented that it was too 'difficult'. 

The coach then suggested to us that we run like ninjas, taking smaller and quicker steps. In fact, he made us practice that. We had to run as close to other pedestrians from behind (sharing the sidewalk) without startling them while we ran past. Turns out my running coach was correct as it helped my team mates and I avoid knee pain.

Here's the evidence. A group of researchers wanted to investigate whether 2 different 2-week partially supervised gait retraining programs were effective for runners with knee pain. They randomly allocated 30 runners to 3 groups. One group focusing on reducing impact, a group on cadence and a control group. 

Visual feedback to reduce impact in the study

The impact group (land softly) received instructions to reduce tibial acceleration (impact) by 50 percent while the cadence group was asked to increase running cadence by 7.5-10 percent. The control group did not receive any intervention.

Running pain (before and during the run), knee function, lower limb kinematics (contralateral pelvic drop, hip adduction, tibial, and foot inclination) were assessed before, immediately and 6 months after the intervention.

Picture A- Injured runner with CPD and right hip adduction

Compared to the control group, both the 2-week partially supervised gait retraining programs focusing on reducing impact and increasing cadence were more effective at improving knee pain up till 6 months after the intervention. In addition, the impact reducing program was more effective at improving knee function immdiately post run. 

So if your knee pain is stopping your from running, try landing softly and/ or taking smaller, quicker steps. Hey, my running coach was right, way ahead of his time. 

Reference

De Souza Junior JR, Rabelo PHR, Lemos TV et al (2024). Effects Of Two Gait Retraining Programs On Pain, Function, And Lower Limb Kinematics In Runners With Patellofemoral Pain: A Randomozed Controlled Trial. 10(1): e0295645. DOI: 10.1371/journal pone.0295645

As Peter Larson's book from 2012 says, tread lightly .....