Could a hip injury 7yrs without teatment end up gettimg worn out needed replacement?

Yes: If there is fracture and healed inappropriately with the wrong angle , displaced from its natural place , will definitely cause problem . The other points are ma-union or non union of the two ends of the bone will result abnormal gait putting pressure on the normal hip resulting damaging of the non injured hip.

Need more info: The knee is a complex joint that carries a substanial burden of weight and which is moved by powerful muscle forces. Hip joint arthritis is therefore common. At your age you should be examined to get a diagnosis. You may need imaging of the hip. Treatments like joint injections, p.T. , and anti-inflammatory drugs may be indicated. There is no reason to expect needing total hip replacement.