الفهرس 
ANATOMY OF SHOULDER JOINTOnly 14 pages are availabe for public view
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Abstract
P
rofessional volleyball is a very quickly, hard hitting sport that sees very huge stress transmitted through the player’s shoulder. Although there are common movements like spike, jump serve and overhead passing between volleyball and other overhead sports like tennis and basketball, however, volleyball motion have special biomechanical premises that have a big difference than other overhead sports.
More over 58% of adolescence whom played at national level also give a history of shoulder pain, 60% of players whom suffer from shoulder injury have pain during hitting through any position of the court, and 77% of players whom suffer from shoulder injury had limitation of power of spike and attack.
The rotator cuff muscles act as the depressors and stabilizers to (GH) joint, allowing the deltoid to ascend the humerus in abduction and extension while maintaining the GH joint center of rotation.
If the ratio between ER / IR muscles strength is insufficient, humeral head and arm will move anteriorly and upwards leading to shoulder injuries.
Acromio-humeral distance (AHD) was defined as the shortest distance between the interior cortex of acromion and the top of humeral head which is measured by ultrasound.
A linear transducer of MSKUS is placed in coronal plane over the anterior aspect of acromion. The normal value of AHD is (7 mm + 4-5 mm)
Narrowing of AHD is associated with rotator cuff muscles degeneration, unknown whether tendon involvements (supra spinatus versus infra spinatus). Tendon tear or muscle degeneration are the most important structural changes in reduced AHD.
We conducted a case control study to asses ER/IR muscles strength using HHD and AHD actively (abduction) and passively (neutral) using MSKUS.
We aim in our study that assessment of rotators cuff strengths and AHD shall help in prediction of shoulder injuries among volleyball players.
This study was conducted in Physical Medicine, Rheumatology and Rehabilitation department in Ain Shams university hospital, and in orthopedic surgery department in Ain Shams University. The protocol was approved by Ain Shams ethical committee for research, and informed consent from each participant was obtained. The protocol was conducted according to the Declaration of Helsinki.
The study population was 60 volleyball players, 30 of them with shoulder pain (injured group) and 30 apparently healthy players (control group).
The study candidates were chosen from volleyball teams and national volleyball team in Egypt throughout the period from june-2022 to july-2022. Following inclusion criterias which were: playing volleyball for more than 4 years, type 1 flat acromion, absence of pain at the time of the test and history of shoulder pain in last 6 months.
Exclusion criterias were: all type of acromion except type 1, injection in shoulder or operation in the last two years.
Our study revealed
On performing ROM for both groups, we revealed that all ROM showed highly statistically significant difference between both groups.
The comparison results between the two studied groups regarding the strength of muscles measured by HHD revealed:
The IR strength for injured group ranged from 12 to 17.5 Kg, with a mean± SD of (14.96±1.36), and in control group ranged from 10.3 to 16.7 Kg, with a mean± SD of (13.85±1.52), with highly statistically significant difference. The ER muscle strength for injured group ranged from 7.2 to12.9 Kg, with a mean± SD of (10.47±1.36), and control group ranged from 9.7 to 15.8 Kg, with a mean ±SD of (12.89±1.55), with highly statistically significant difference.
The ratio between ER and IR muscles strength in injured group ranged from 0.57 to 0.79, with a mean ±SD of (0.69±0.05), and control group ranged from 0.9 to 0.96, with a mean ±SD of (0.93±0.02), with highly statistically significant difference.
The comparison results between the two studied groups regarding the ultrasound results revealed that:
The AHDP for injured group ranged from 0.83 to 1.2, with a mean± SD of (1.01±0.08), and control group ranged from 0.91 to 1.21, with a mean± SD of (1.06±0.07), therefor it has statistical significance difference.
The AHDA for injured group ranged from 0.45 to 0.87, with a mean± SD (0.64±0.07), while control group ranged from 0.7 to 1, with a mean± SD of (0.79±0.08), therefor it has a high statistical significance difference.
Regarding rotator cuff state among injured group, 6 players (20%) had sub-acromial sub-deltoid bursal inflammation, 7 players (23.33%) had supraspinatus tendinopathy, 15 players (50%) had supraspinatus old partial tear and 2 players (6.67%) had a combined injury as sub-acromial sub-deltoid bursal inflammation and supraspinatus tendinopathy.
On studying correlation between Dynamometer strength ratio and different parameters showed that there were a positive correlation with AHD measured actively according to spearman co- efficient factor.