Considering the medical, football implications of Marcus Martin's return to practice last week

Six weeks ago, San Francisco 49ers rookie center Marcus Martin was carted off the field early in the fourth quarter of the preseason victory over the San Diego Chargers. As we know, the 49ers do not elaborate on any injury and are reluctant to even provide a diagnosis.

When looking at the play in which Martin was injured, Martin got rolled up from behind during a running play. Multiple reports indicated his knee was dislocated and would miss up to eight weeks. Martin returned to limited practice this past Wednesday after sitting out four weeks. He was limited all three days, and listed as doubtful on the injury report. This followed the first four weeks in which he was listed as "out". He was inactive on Sunday during the 49ers win over Kansas CIty, but it appears Martin is well on the road to recovery.

Last year, Martin dislocated his left kneecap in USC's regular-season finale against UCLA. Since the 49ers did not place Martin on injured reserve after this most recent injury, it was a good sign they expected him to return and contribute (if necessary) at some point this season. His return to practice shows he is indeed in line for return within the 8-week projected time frame.

A dislocated knee is a serious, painful injury, but the long-term consequences are not dire. The knee cap (patella) sits in the groove at the bottom of the thighbone. It stays in that groove and supports the quadriceps muscle when the knee is extended. When a subluxation occurs, the kneecap partially moves out of its position. It can be the result of a previous subluxation or an inherent tendency for the kneecap to slide to the outside. When the kneecap moves all the way out, usually to the outside of the leg, it has been dislocated. A dislocated kneecap causes instability, severe pain, and swelling and must be manually repositioned by a doctor.

Martin's injury has been reported as both a dislocated knee and a dislocated kneecap. It should be noted there is a substantial difference between a dislocated kneecap and a dislocated knee. When the knee is dislocated, damage to the peroneal nerve is possible and if damaged, it usually results in a drop foot. A person cannot walk on the foot without dragging his or her toes. Running is extremely difficult and if it happens to a NFL player, it could end a career.

Given that Martin has previously dislocated his kneecap and most media do not focus on the medical type of details, it is most likely Martin suffered from a dislocated kneecap. So, once the MRI was performed, it likely gave the 49ers a good idea of the nature and extent of the injury of the knee. If the peroneal nerve escaped damage, it would have assured the 49ers Martin could return within a reasonable time frame, i.e., 6-8 weeks.

Every person recovers at a different pace and doctors are careful to return a player to the field until the knee shows it is fully recovered. Doctors will not give time periods for recovery. Rather, they aim to have the player's knee fully immobilized for 3-weeks. When the player can straighten his knee without pain, strength is 100% regained, all swelling has subsided, and when he can bend, squat and walk without any pain -- it is the best indicator. Once that threshold is crossed, doctors will allow a player to return to practice.

Therefore, it is a good sign Martin has returned to practice, even on a limited basis. It appears the type of injury may have given the 49ers an initial scare, but the diagnostic tests likely revealed good news. I suspect the 49ers will continue to ease Martin into practice without rushing him, so as not to worsen his injury and get him the necessary rehabilitation to restore his range of motion.

Once healthy, it will be interesting to see if Martin can impact the offensive line in a positive way. The third round pick played center at USC, but can also play guard, and had been slated to back up Daniel Kilgore. Given the 49ers have carried Martin on the roster to allow for his recovery shows they undoubtedly have confidence in Martin's abilities.

Even injured, Martin made the 53-man roster and showed himself during the preseason to be a naturally physically gifted athlete. Obviously, Martin has suffered a setback. If offensive line coach Mike Solari can impact Martin as he has other offensive linemen, the 49ers confidence in Martin is probably not misplaced.

After the draft, David Neumann of Niners Nation broke down in greater detail how Martin has the ability to drive defenders off the ball and creates movement in the run game. At the same time, Martin is a good anchor and has a natural instinct for being in the right position for pass protection. It remains a question if Martin can make an immediate impact, but 49ers could use his type of natural strength and good instincts on the offensive line.