July 29, 2011

Collateral Damage

Explaining Sprains

by Corey Dawkins and Ben Lindbergh

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Rickie Weeks, MIL (Left ankle sprain) [AGL: 29, ATD: -.003] (Explanation)
The Brewers' chances took a serious hit on Wednesday night once Weeks went down. In the midst of one of the top offensive seasons among NL second basemen, Weeks was lunging for first base trying to beat out a grounder when he injured his ankle. It rolled inward significantly into inversion (he was lucky that he did not suffer a concurrent injury with that mechanism). After the medical staff ruled out a major fracture at the stadium, Weeks went to the hospital for further specialized imaging and was diagnosed with a sprained ankle.

In reality, any sprain, even the mildest one, does ligament damage. When potential ligament damage is discussed in the various news and media outlets, it’s implied that it involves partial or complete tearing of the ligament. Grade II sprains include anything from 20 percent to 80 percent or more of the fibers torn, leaving a wide range in the prognosis that isn't very helpful to most of us trying to plan our fantasy trades approaching the wire.

Lateral ankle sprains like the one Weeks suffered can advance much faster than the dreadful “high ankle” or syndesmotic sprain. On the outside of the ankle, there are three ligaments that are generally considered part of the lateral ligament complex: the anterior talofibular ligament, the calcaneofibular ligament, and the posterior talofibular ligament. The most common ligament sprain in the ankle involves the anterior talofibular ligament (ATFL), in part because it is the weakest of the ligaments.

The calcaneofibular ligament (CFL) is also involved in approximately 50-60 percent of these injuries, while the third ligament, the posterior talofibular ligament or PTFL, is injured in less than 5 percent of the cases. When people speak about the high ankle sprains, they are discussing the anterior inferior tibiofibular ligament or the posterior inferior tibiofibular ligament, which Weeks may have done at least some damage to.

So far, we’ve discussed how the different grades can be helpful but not extremely specific in terms of the actual number of fibers torn. Mild sprains involve microscopic tearing of the collagen fibers in the ligament but no visible tearing. Treated with minimal splinting, weight bearing exercise as tolerated, and physical therapy, players can return fairly quickly—almost always within a week—if they miss any time at all.

In moderate sprains, there is complete tearing of some of the collagen fibers, but not all of the fibers are torn. Physical therapy starts off more slowly than in cases of mild sprains, with the player usually immobilized in an air cast splint or walking boot. The ligament (or ligaments) needs to heal, and if stressed too early with overly aggressive physical therapy, it can heal in an elongated, stretched-out position. This can contribute to further instability in the future and may end up requiring surgery. Players often, but not always, end up on the disabled list with these sprains, but they are usually able to return within six weeks. This appears to be the type of strain that Weeks suffered.

Severe sprains involve complete or essentially complete tearing of the ligaments. Often, this type of sprain is referred to as a “tear” or “rupture” in reports. Players with severe strains are immobilized for a period of time, and surgery may be considered if the ankle is grossly unstable or injured in conjunction with other structures. These sprains generally heal in six to eight weeks or more.

Weeks was placed on the disabled list and is expected to miss between three and six weeks.

Dustin Moseley, SDN (Left shoulder dislocation) [AGL: 51, ATD: -.021] 
After Moseley re-injured his left shoulder on Tuesday night, it was announced on Wednesday that he will have surgery after the season. He has a torn labrum and stretched capsule, not an uncommon finding in cases of multiple dislocations. The exact surgical procedure depends on the location and size of the tearing in the capsule and labrum.

Moseley will continue to try to pitch through the remainder of the season, although you can be sure that he's going to bunting almost every time up. His strength was sufficient post-game to consider making his next start. The risk is not just to the left shoulder, but to his biomechanics, a change in which could threaten his dominant arm, since pitching is so reliant on timing and positioning of the arm in addition to the strength component. If he does suffer another episode, surgery may be necessary sooner rather than later, but for now Moseley will attempt to get back on the mound.

Jordan Schafer, ATL (Chip fracture left middle finger) [AGL: 30, ATD: -.052] 
Chase d'Arnaud, PIT (Chip fracture right little finger)
Chip fractures in the fingers can often be managed without a trip to the disabled list, but Schafer was unsuccessful in his attempt to play through it. As long as the chip fracture is stable, players almost always end up missing close to the minimum. With chip fractures in the fingers, it is not uncommon to have significant swelling around a joint following the injury, and the player often assumes it's just a sprain. If all the structures are not tested, they can be mismanaged and end up requiring surgery. Schafer and d'Arnaud will likely both avoid surgery and should be back in roughly three week.

Clay Buchholz, BOS (Low back strain) [AGL: 31, ATD: -.034] 
Even in an uncertain world, the saga of Buchholz's back must be considered unusual. Each bullpen session that is scrapped strengthens the suspicion that something else is going on besides a simple low back strain. Luckily, he has been able to continue some throwing and is therefore at less risk than Josh Johnson for missing the rest of the season.

For those who follow the Red Sox, this pattern of goals being consistently pushed back near the trading deadline can't help but bring back memories of Brendan Donnelly in 2007. After all the moves were done, it was announced on July 31st that he would need season-ending Tommy John surgery. This sense of something more serious is only growing regarding Buchholz. He's going to have another examination this weekend, so we will presumably have more information by Monday.

Craig Gentry, TEX (Concussion) [AGL: 29, ATD: +.012] 
Gentry was the latest to end up on the 7-day disabled list with a concussion and was retroactive to July 25th. Not only was there a sharp blow directly to the head, but we also saw a rapid rotation of his head as he slid into second base. This is now his fourth diagnosed concussion due to baseball, according to Gentry, so a more conservative timetable will likely be considered. There hasn't been an estimate as to when he will be back, but we will keep an eye on this.

Flesh Wounds: Tony Cruz (right hand contusion)and Gerald Laird (sprained left ring finger)both left last night's game against the Astros and are day-to-day... Kenley Jansen was discharged from the hospital yesterday after experiencing an irregular heartbeat and could be available out of the bullpen today... Nick Punto left last night's game with a strained left oblique and is a good candidate for the disabled list... Carl Crawford is battling a left elbow strain but did manage a pinch-hitting appearance yesterday... Alexi Casilla was placed on the disabled list with a right hamstring strain... Al Alburquerque is suffering from right forearm inflammation and may end up needing another trip to the disabled list... Brian Roberts is continuing to battle migraines and likely will miss the rest of the season... Chipper Jones will probably remain a pinch-hitter for the next few days while he battles back from a strained quad... Mitch Stetter will have surgery on a torn labrum in his left hip.

Corey Dawkins is an author of Baseball Prospectus. Follow @CoreyDawkinsBP
Click here to see Corey's other articles. You can contact Corey by clicking here
Ben Lindbergh is an author of Baseball Prospectus. Follow @benlindbergh
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