PORTLAND, OREGON - DECEMBER 06: Rodney Hood #5 of the Portland Trail Blazers lays on the court after being injured during the first half of the game against the Los Angeles Lakers at Moda Center on December 06, 2019 in Portland, Oregon. NOTE TO USER: User expressly acknowledges and agrees that, by downloading and or using this photograph, User is consenting to the terms and conditions of the Getty Images License Agreement. (Photo by Steve Dykes/Getty Images)

Portland Trail Blazers’ wing Rodney Hood ruptured his left Achilles tendon Friday night. He will likely miss at least 9-12 months.

It happened with 3:30 remaining in the first quarter. Portland Trail Blazers‘ wing Rodney Hood had just gathered a rebound off an errant LeBron James fade-away when he turned to push the ball in transition. The high-pitched shrill of referee Jon Goble’s whistle rang throughout the Moda Center. Hood had crumpled to the court in pain.

Hood, who was in the midst of a career-year during his first full season in Portland, had torn the Achilles tendon in his left leg.

The Achilles tendon is a strong, cord-like structure that attaches the calf muscle group – comprised mainly of the gastrocnemius and soleus, collectively known as the triceps surae – to the heel. The Achilles is under a severe amount of tension at all times, making the calf one of the primary force producers in the lower extremity.

During powerful activities such as sprinting and jumping, the Achilles plays the integral role of storing and then quickly releasing force to help propel the body forward or upward. It does this through both passive and active means; the tension in the tendon allows for the structure to release significant passive force, while the strength of the calf muscle group allows it to transfer and release additional active force. This force is stored during what is known as the amortization phase of gait.

The amortization phase begins when the foot makes contact with the ground. During this time, the calf muscles slowly (relatively, that is) lower the heel towards the ground with what is known as an eccentric contraction. Once the heel makes contact with the ground, the calf muscles engage in a new way, producing a concentric contraction. This abrupt switch in muscle contraction type places a significant amount of force and strain through the Achilles and allows for the structure to produce a significant amount of power. When athletes partake in plyometric training, they are working to improve the force generative capacity of their Achilles tendons during the amortization phase (there is also evidence that plyometric training has an injury preventive effect, but that’s beyond the scope of this article).

If the Achilles is unable to adapt to the amount of force it is subjected to during the amortization phase, the structure will give. Just like with any other muscle or tendon injury, Achilles strains are graded on a one-to-three scale; grade one injuries are minor while grade three injuries are full-out ruptures. Because of the amount of tension present in the Achilles, it is rather common for them to completely rupture.

However, healthy Achilles tendon tissue rarely ruptures; a preponderance of Achilles ruptures occur among players who previously reported Achilles tendon pain. This was the case with then-Golden State Warrior Kevin Durant as well as with Hood, who stated that the same Achilles was bothering him during Portland’s previous game against the Sacramento Kings.

Dr. Maggie Bryant, a physical therapist and the Director of Rehabilitation for the Los Angeles Clippers, told me previously, “A lot of the research [shows that] a high percentage [of players] have pre-existing tendinopathy; it’s not healthy tendon, it’s damaged.” The damaged tissue is unable to tolerate the transition from eccentric to concentric muscle force, causing it to rupture.

This can be plainly seen during Hood’s injury.

Hood lands from gathering a rebound and quickly transitions to running up the court. That is a textbook example of the amortization phase. Immediately after his initial push, he falls to the ground with his knee bent, doubled over in pain; these are textbook Achilles tendon rupture signs.

Achilles tendon ruptures usually require surgical intervention, with the associated recovery timeline being at least 9-12 months. It takes time for the repaired Achilles tendon to recover and build up strength, partially due to relatively poor blood flow compared to the musculature it attaches to, as well as the physical changes that occur to the Achilles tendon itself.

The Achilles tendon is formed by strands of collagen, which is elastic yet very durable. “When you tear the tendon, the actual collagen changes,” said Dr. Bryant. “The tendon collagen [goes from being] elastic and it changes to become stiffer. Over time, it becomes more difficult to build that power and energy storage.” (For further discussion on Achilles tendon injuries as well as the return to play process with more insight from Dr. Bryant, check out these three articles.)

The inability of the “new” Achilles tendon to generate power is a large reason why Achilles tendon injuries are so difficult for NBA players to return from. The return-to-play rate for NBA athletes who suffer Achilles tendon injuries ranges from 61-80 percent, with the vast majority unable to return to their prior levels of production.

This would be a devastating blow for Hood, who was shooting a career-high 49.3 percent from 3 and 50.6 percent from the field overall in 29.5 minutes per game. Hood had been an integral member of the Trail Blazers’ most utilized and productive lineups and was well on his way to producing at levels well above the 2-year, $11.7 million contract he signed during the offseason.

The loss of Hood now presents a void at the wing for the underperforming Trail Blazers that is unlikely to be filled adequately in-house. Hood’s devastating injury is yet another for the seemingly snake-bitten Portland franchise, already missing big men Jusuf Nurkic, who fractured both his left tibia and fibula in March, and Zach Collins, who dislocated his left surgery and required surgery.