The biggest health dangers in combative sports are brain trauma from KO’s and TKO stoppages involving brain rattling. Concussions and CTE are to be taken seriously. So bouts allowing knees to the head of grounded opponents likely see far more dangerous stoppages and fight ending sequences right? Not necessarily so according to a recent study published in the latest Journal of Combat Sports Medicine.

In the study, titled Knees to the Head of a Grounded Opponent: A Single Promotion Retrospective Study, the authors reviewed all fights from One Championship in 2023 (a promotion that allows knees to the head of grounded fighters). These bouts were contrasted with fights under the Unified Rules which prohibit such strikes.

The authors (who are experienced ringside doctors including the current and past president of the Association of Ringside Physicians) reviewed the bouts to see how often knees to the head of grounded fighters were decisive in fight ending sequences. Their findings were that “the rates of KO/TKO’s do not appear to be greater in ONE which permits grounded knees“. Their conclusion was as follows:

Grounded knees to the head were frequently used in
ONE bouts but were rarely the decisive factor in fight
outcomes. The distribution of fight results in these
matches closely mirrored those seen in UFC fights
under more restrictive rules, suggesting that the rule
permitting grounded knees does not significantly alter
the overall nature of competition

The authors called for more data on the injuries from these strikes and being cautious if considering rule modification however, much like the 12-6 elbow data that led to that foul being removed, studies such as this could prove useful if ever revisiting this foul under the unified rules.

The full abstract reads as follows:

ABSTRACT
Background: Rules regarding knee strikes to the
head of a grounded opponent in mixed martial arts
(MMA) vary across promotions, with “ONE” (an
MMA promotion) allowing this technique under its
global rule set.
Purpose: To evaluate the impact of knees to the
head of a grounded opponent on fight outcomes and
duration within ONE events.
Methods: A retrospective observational study was
performed on all ONE MMA bouts in 2023. Data on
fighter demographics, fight outcomes, and grounded
knee strikes were analyzed. Knee strikes were judged
by two experienced ringside physicians for effect on
fight outcome.
Results: Among 143 fights, 49 (34.3%) involved
grounded knee strikes. Knee strikes had significant
effect on fight outcome in 18.4% of these bouts.
No significant differences in fight outcomes were
observed between bouts with and without grounded
knees. Fights involving grounded knee strikes were
significantly longer in duration (p = 0.039).
Conclusions: Knee strikes to the head of a grounded
opponent were common and associated with
increased fight duration but had limited influence on
fight outcomes. These findings contribute to ongoing
discussions regarding rule standardization and safety
in MMA.