Pocketpedia is good. If you're doing any msk, the "3 minute musculoskelteal and periphreal nerve exam" is an excellent book to have on hand. It goes over a lot of anatomy as well, but I preferred my Thieme anatomy book for anatomy review. I recommend every PM&R resident get the 3-minute exam text.
If you're doing a dedicated inpatient month (TBI, SCI, etc.), there are some nice smallish books that go over those topics. I recommend them for residents ("Essentials of Spinal Cord Injury" by Sabharwal, "Manual of Traumatic Brain Injury Management" by Zollman) when they are on an SCI or TBI rotation as you can easily get through a chapter or two during down time during the day. Much easier to read than Braddom. There are also some very white-coat pocket-friendly monographs, "The Rehabilitation of People with Traumatic Brain Injury" and "The Rehabilitation of People with Spinal Cord Injury," as well as "Essentials of Inpatient Rehabilitation." I think all are written/edited by Nesathurai. The SCI and general rehab one have newer editions with color on the covers, but the older editions are fine ok--the texts really go over the basics. I liked "Essential Physical Medicine & Rehabilitation" by Grant when I was an M4--it's more in essay/novel format and I found easier to read (I don't like bullet points). PM&R Secrets isn't too bad either, but in my opinion is better as a supplement.
Do not by any means buy all of the books above! Those are just what I found helpful over the years. As a med student, I would have one general text to read over each night (either rotation-specific like TBI, or one of the general texts), and use a pocket reference or two during the day when there's downtime or you need to reference something quickly.