There was a lengthy stoppage as the youngster clashed heads with an opponent just before the break, with an ambulance called to take the prospect away for further treatment.
All at the club will be wishing Pattenden a speedy recovery and the 2-1 defeat for Worthing - a third in succession - almost became irrelevant following such an sickening injury.
Returning Zack Newton, rejoining on a one-month loan deal from Welling United on Thursday, fired the visitors into a 22nd-minute lead.
But goals after the restart from Ibrahim Olutade and Shaun Okojie ensured Tanners completed a turnaround victory.
Worthing had wing-back Alex Parsons dismissed after picking up a second bookable offence 20 minutes from time before striker Callum Kealy missed a penalty - all while the scores were locked level at 1-1.
Hinshelwood handed debuts to Billy Barker and Eoin Kirwan - signed hours before kick-off - while Newton made his first appearance since agreeing a loan return.
Things could not have started any better for the visitors as the returning Newton handed them the lead on 22 minutes.
But there was an extended delay soon after. Pattenden remained down for a sustained period following a nasty clash of heads.
An ambulance was called and play was stopped until the youngster was treated and taken to hospital.
The hosts had a leveller ten minutes after the restart courtesy of Olutade and would go on to win it.
Prior to the Tanners' winner, Parsons received a second yellow card and Worthing were reduced to ten men 20 minutes from time.
Yet, the visitors had a great chance to restore their lead minutes later, only for Australian striker Kealy to see his penalty saved.
Okojie then grabbed a winner for Leatherhead ten minutes from time to complete another difficult league outing for Worthing.
WORTHING: Perntreou; B.Barker, Colbran, Jones; Parsons, Clarke, Kirwan, Pattenden; Newton, Pearce; Kealy. Subs: Gould (Pattenden, 45), Jelley (Kealy, 73), Skerry, Relf, Mthunzi.
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