# Lab Class 12

### Learning Objectives

By the end of this lab class:

• You are able to describe the concepts of special testing and joint play.
• You are able to rate the quality of a special test when evaluating values for sensitivity and specificity.

### Introduction to Special Testing and Joint Play

Welcome to lab class 12!

We hope that your first assessment exam went well and that you are eager to start the second part of assessment 1!
In the second part, you are going to discover special testing and joint play of the lower extremity, as well as basic, special testing and joint play of the upper extremity.

Statistics

Reliability is the degree to which a research instrument produces consistent results. So measuring someone’s height and weight would usually be extremely reliable. One important form of reliability in statistics is the inter-rater reliability. It describes how reproducible outcomes are if two different examiners conduct the exact same test.

Another important form of reliability is the intra-rater reliability. “Intra” stands for within, which in this case describes “within” the same person. In other words: how reproducible are outcomes of a test if it is performed twice by the same person.

Special tests are used to either rule in or rule out a specific pathology. There are good and bad examples of special tests. In order to rate the quality of a special test, two terms are essential: Sensitivity and Specificity

Watch the video below, where Kai visually explains the terminology and gives practical examples:

Look at this table to learn about the sensitivity and specificity of the tests we present in this module.

Joint Play:
During Joint Play you are assessing the capsular apparatus and you are trying to identify whether it is  the source of dysfunction. The movements you will assess are not possible to be voluntarely executed by your patient through the use of muscles and are very small (~4mm in each direction). They are essential for proper joint function nonetheless.
Joint play movements usually contain tractions (seperation of the two joint surfaces), compressions (approximation of the two joint surfaces), glides (moving one joint surface anteriorly/posteriorly/medial/lateral on the other), and sometimes spins (rotating one joint surface on the other) and they are mostly done in the Maximally Loose Packed Position (MLPP). The MLPP puts the joint under the least amount of stress and the joint capsule has its greatest capacity, meaning that passive structures (e.g. ligaments) are in the position of greatest laxity and the joint surfaces have minimal congruency. This allows for greatest passive seperation of the two articular surfaces.

In the next classess, you are going to learn about Joint Play and Special testing of the different joints in the extremities.

1) Get together with your classmate and practice joint play. Take your partner's index finger, fixate the metacarpal bone with one hand, and perform the following movements with your other hand on your partners proximal phalanx:

- Traction + Compression
- AP glides + PA glides
- Medial + lateral glide

2) Now try to estimate how much you can actually move in all the above mentioned directions. Compare both sides, write down differences and share your results with your classmates through Google Drive!

Preparation for next week:

1) Think about why joint play is usually done in MLPP position?
2) In order to be best prepared for next week's lecture read about:
- Labrum tear in the hip joint
- Femoroacetabular impingement (Pincer + CAM)