16 from whom the whole body, joined and knit together by what every joint supplies, according to the effective working by which every part does its share, causes growth of the body for the edifying of itself in love.
by what every joint [ligament] supplies,
A “joint” in this context means ligament. “Supplies” refers to a supporting ligament. The constituent members of the body give mutual assistance to each other. A “joint” is the point of union where the supply passes to the different members of the body of Christ. The “joint” furnishes the body with the materials for growth. The parallel passage is Colossians 2:19:
…and not holding fast to the Head, from whom all the body, nourished and knit together by joints and ligaments, grows with the increase that is from God.
“Joint” or ligament means band. The idea is mutual assistance among constituent members of the body of Christ. Nourishing flows from Christ through members of His body called the church.
“By” means the agency that joins members of the body together. The joints of supply bind members of Christ’s body together. The body or the church is symmetrical in function.
It is not just a few but “every joint” that supplies the needs of the body. Each ligament connects to a different part of the body to provide support. As the different parts of the body work together, they work as a unit serving the Lord.
Church members are also the channels by which Christ makes “supply.” The organic union of the body with Christ has a dynamic relationship; it will cause members in the body to grow more to be like Christ.
Members of the body of Christ joining together or uniting together with their gifts produce growth in the church.
As the human body has certain vehicles that carry what is necessary to the various parts of the body, so believers edifying one another is the life blood of the church. That life flows from the Head, from the Son of God. Those vehicles come from the gifts of verse 11. They do this through proclaiming the Word—the Word that comes from Christ. The joining of truth with believers connected to each other pervading the church is what causes it to grow.
The body of Christ functions best when everyone uses their spiritual gifts in fellowship with one another. As we hold our fellowship with the Lord closely, we fellowship with one another more significantly.
Athletes in American football often have ligament injuries. If the local church has ligament damage, it will not connect with others in ministry in unity. If this happens, a problem develops with the dynamics of the church. If a ligament in the leg becomes damaged, it will be very difficult to function as an athlete. This is also true of the church.