it appears from your description of the surgical report that the surgeon completely amputated the toe from top to bottom in line with the skin crease where the toe meets the foot and where the toe bends (total amputation in which the whole toe is removed)

if this assumption proves to be correct, then the other two plausible terms "skin fold" and "skin flap" would not apply to this context

sources:

Fixing Your Feet: Injury Prevention and Treatments for Athletes
https://books.google.com/books?isbn=0899978312 -
John Vonhof - 2016 - ‎Sports & Recreation
Injury Prevention and Treatments for Athletes John Vonhof ... to side around the heel. to tape the bottom of the foot is using strips side to side from the toes to heel. ... Trim the front edge to follow the contour of the toe base, avoiding the crease.

Fixing Your Feet - Frequently Asked Questions - John Vonhof
www.johnvonhof.com/fixing/Frequently-Asked-Questions.html
Frequently asked questions about foot care. ... I prefer to tape bottom to top, avoiding the crease at the bottom base of the toe. Then run another strip side to side.

Toe Amputation - The Foot Health Clinic
www.thefoothealthclinic.com/index.php/patient.../toe-amputa...
The Procedure. Partial Amputation: The tip of the toe and the nail are removed. Total Amputation: The whole toe is removed. .Approximate procedure time 15-30 ...

Toes keep splitting open - The Student Room
https://www.thestudentroom.co.uk/showthread.php?t=1341591
20 jul. 2010 -
It's always along the crease on the underside of my toe (the bit where your toe folds over).

Toes keep splitting open - The Student Room
https://www.thestudentroom.co.uk/showthread.php?t=1341591
20 jul. 2010 -
It's the crease that connects the toe to my foot, so naturally as I walked it opened it up more ...

Skin Cracks Where Toe Bends! - Mamapedia™
https://www.mamapedia.com/article/skin-cracks-where-toe-bend...
13 jul. 2009 - ... problems with the skin cracking at the crease where the toe bends.

"Cracked skin under toes": Skin Problems & Treatments Community ...
forums.webmd.com/3/skin-problems-and-treatments.../1265
The skin splits right where the crease of her toe meets her foot.

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the analogous term in German written either as "Hauptumschlagsfalte" or "Hauptumschlagfalte" refers to abdominal, ear, pectoral and upper / lower eyelid skin creases rather than skin flaps or skin folds:

Digitale Revolution in der Chirurgie: 119. Kongress der Deutschen ...
https://books.google.com/books?isbn=3642557155 -
Jörg Rüdiger Siewert - 2013 - ‎Medical
Kaudal wird der Schnitt über den Tuber calcanei in der Hautumschlagsfalte in Richtung Metatarsale-V-Basis geführt. Dabei wird einschichtig bis auf die ...

Ergebnisse der Chirurgie und Orthopädie
https://books.google.com/books?isbn=3642947409 -
2013 - ‎Medical
Es ist zweckmäßig, den hinter dem Ohr gelegenen Vertikalschnitt nicht näher als / cm an die Hautumschlagsfalte heranzulegen, damit der äußere Gehörgang ...

Bauchdeckenstraffung - Mann - Facharzt für Plastische & Ästhetische ...
www.drdabernig.com/behandlungen/bauchdeckenstraffung-mann/
Feb 20, 2017 - Der Schnitt erfolgt an der Hautumschlagsfalte im Unterbauch. Das überschüssige Gewebe wird mobilisiert und letztendlich entfernt.

dr-lang.eu- plastische Chirurgie | Oberlidkorrektur | Gesicht | Content ...
www.dr-lang.eu/oberlidkorrektur.html
Die Narbe liegt in der natürlichen Hautumschlagsfalte des Oberlids und wird dadurch geradezu unsichtbar sein. Der operative Eingriff kann normalerweise gut ...

Wann ist der richtige Zeitpunkt für eine Oberlidstraffung? | Lidkorrektur ...
https://www.lidkorrektur-muenchen.de › Schlupflider
Ist die Hautumschlagsfalte nun sichtbar geworden? Wenn ja, dann wird eine Lidstraffung bei Ihnen sehr wahrscheinlich den gewünschten Erfolg bringen.

Röntgenfibel: Praktische Anleitung für Eingriffe in der ...
https://books.google.com/books?isbn=3642967744 -
G. W. Kauffmann, ‎W. S. Rau - 2013 - ‎Medical
Die Punktionsstelle richtet sich nach dem Leistenband und nicht nach der Hautumschlagfalte in der Leiste. Zunächst müssen also die Spinailiaca anterior ...

Verlogene Schönheit: Vom falschen Glanz und eitlen Wahn
https://books.google.com/books?isbn=3641036909 -
Werner Mang - 2009 - ‎Social Science
Wenn sich im Stehen die Brustwarzen unterhalb der Hautumschlagfalte der Brust befinden, spricht man von einer Hängebrust. Für viele Frauen stellt ein ...

Augenlidstraffungen - Dr. med. Holger Marsch
www.dr-holger-marsch.de/behandlungen/augen
Die Narbe am Oberlid liegt ohnehin in der Hautumschlagfalte und ist nur bei geschlossenem Auge zu sehen, die Unterlidnarbe kann, wenn störend, ...

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aka "flexor crease" and "plantar flexural crease":

Tendon Transfers and Treatment Strategies in Foot and Ankle Surgery, ...
https://books.google.com/books?isbn=0323287077 -
Bruce Cohen - 2014 - ‎Medical
A transverse incision 1 cm in length is made in a plantar flexor crease at the base of the great toe. The incision is carried down to the level of the FHL tendon.

The Diabetic Foot: Medical and Surgical Management
https://books.google.com/books?isbn=161779791X -
Aristidis Veves, ‎John M. Giurini, ‎Frank W. LoGerfo - 2012 - ‎Medical
The postoperative care mandates a period of total non-weight bearing of at least 4 ... a small stab incision just proximal to the flexor crease of the affected toe.

Surgical off-loading of the diabetic foot - ScienceDirect
www.sciencedirect.com/science/article/pii/S0741521410013297
RG Frykberg - ‎2010 - ‎
... is introduced 1 cm proximal to the proximal plantar flexural crease of the toe ... The fourth toe had resection of osteomyelitis, 4 weeks postoperatively, done in .... of total contact cast and percutaneous TAL against a total contact cast alone.

Fisher's Contact Dermatitis - Page 356 -
https://books.google.com/books?isbn=1550093789 -
Robert L. Rietschel, ‎Joseph F. Fowler, ‎Alexander A. Fisher - 2008 - ‎Medical
Plantar dermatitis may be seen when the patient is allergic to rubber, ... The most typical sole involvement spares the instep and the toes' flexural creases.

Contact Dermatitis - Page 704 -
https://books.google.com/books?isbn=354031301X -
Peter J. Frosch, ‎Torkil Menne, ‎Jean-Pierre Lepoittevin - 2006 - ‎Medical
... central dorsal aspect of the foot and/or over the plantar aspect of the foot [7]. ... interdigital spaces, flexural creases of the toes and thicker-skinned heel area ...

Atlas Foot and Ankle Surgery, Second Edition
https://books.google.com/books?isbn=1841841951 -
Nikolaus Wülker, ‎Michael Stephens, ‎Andrea C. Cracchiolo - 2005 - ‎Medical
Surgical technique The first incision is made horizontally in the plantar skin at the level of the proximal flexor crease of the affected toe. It is 5-6 mm long and ...

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Surgical off-loading of the diabetic foot - Journal of Vascular Surgery
www.jvascsurg.org/article/S0741-5214(10)01329-7/pdf
RG Frykberg - ‎2010 -
A blade or 18-gauge needle is introduced 1 cm proximal to the proximal plantar flexural crease of the toe (Fig 4).

Office Procedure for Diabetic Toe Ulcerations - Medscape
www.medscape.com/viewarticle/555301_2
The first step is to make a target incision between the plantar creases of the metatarsophalangeal (MTP) and PIP joints at the paramedial aspect of the toe (Figure 1).