Simple personal injury cases may proceed without expert medical testimony when injuries and causation are within common knowledge and understanding. Broken bones, cuts, and bruises from clear trauma often don’t require expert explanation. Complex injuries, disputed causation, or pre-existing condition aggravation typically require expert testimony establishing medical probability. Soft tissue injuries increasingly need expert support due to defense challenges. Treating physicians may provide lay observations about visible injuries without qualifying as experts. Medical records alone rarely suffice without authenticating testimony. Judges serve as gatekeepers determining when expert testimony is necessary. Cases dismissed for lacking required expert testimony cannot be refiled after limitations expire. Strategic decisions about expert necessity must be made early in litigation.