It looks like the Texans were not straightforward with their description of Manning's injury. At first they report a stress fracture of the fibula and later reported a significant knee hyperextension injury. Keeing in mind the the injury occurred mid October of last year, with Manning revealing that he had 6-8 still to go on his rehab before making on the field, I've been trying to put things together in my head. All sources, including Rotoworld, have continued to report that Manning was recovering from surgery fibula fracture surgery. An isolated fibula fracture, even a complete one, would require only 6-8 weeks total rehab. Manning previous had that type of injury and actually came back early after 5 weeks. Today, it's ~5 1/2 months since the injury. So either he had a complication from surgery........which the Texans never reported to have occurred or had more extensive injuries.
I found this isolated Tweet I never saw back at the very end of the year.:
@HoustonTexans RT @DeepSlant: Manning says he is 3 weeks ahead of schedule in his rehab. Hopes to be ready before OTAs even. #Texans
8:08 AM - 30 Dec 2013
Then I went back and tried to get a still of when the injury occurred.
It appears that with such a long rehab, injuries sustained in addition to the fibula fracture (which was likely the proximal segment that is attached to the lateral collateral ligament) would definitely have to have included surgery...........for a tear of the posterior cruciate ligament (this ligament is the "check" ligament that prevents forward bending of the knee) and most likely for the lateral collateral ligament/fibula fracture segment, and also for the lateral meniscus, possibly the medial meniscus. It would not be unusual for any combination of this injuries included direct knee cartilage damage.
A posterior cruciate tear alone that requires surgery requires a very long recovery. When muscle strength is adequate, light jogging only begins at ~6 months and full return to play is not atypically allowed until 9-12 months after surgery.
This could very well explain why such concern regarding what was originally reported as a "hairline fracture of the fibula."