It is possible that a fall from a horse can cause a groin herna, but the reports I have read about horse falls talk more about post-traumatic diaphragmatic hernia.

Indirect inguinal herniae present clinically through the potential space of the inguinal canal, alongside the processus vaginalis. Thus, they can present at birth, during infancy, commonly in young, muscular adults more than direct herniae, which commonly present in older adults with week abdominal walls. Any factor that raises the intra-abdominal pressure can cause a pre-formed sac to become clinically manifest, by causing protrusion through a stretched/injured external ring. Usually, this is the result of recurrent or constant pressure; atleast during the final restive stage, though a sudden, severe raise in pressure can cause the same result. Although quite plausible, due to the  interesting circumstances of this case, it is worthwhile reporting in a peer-reviewed journal,such as the World Journal of Hernia etc. A combined article with a surgeon would be useful,maps they would be able to rule out pre-disposing and contributory factors, as well,as providing clinical and operative findings. A simple review of literature via Medline,,Cochrane and other similar databases would be useful.

Traumatic Inguinal hernia have been reported

I have operated 3 week back a case traumatic rt. inguinal hernia due to fall from bike.

http://www.wjes.org/content/5/1/16

I haved never observed a traumatic inguinal hernia in all my professional life. Although some publications reported anecdotical cases, the data comes from the words of the patients. Therefore, noone can be sure that the groin was normal before. Probably, the efforts or the fall could make the hernia more visible.

It is important to define our semantics in this instance.

The formation of an inguinal hernia is a process.See the excellent summary above from Kamal Heer.

A hernia with a sac and a clinical cough impulse must certainly have been preexisting. However, a small hernia that is not clinically apparent, and therefore undiagnosed, can certainly become apparent after a traumatic incident, such as a fall off a horse.

The excellent summary by John Moorhead in 1940, in the American Journal of Surgery, is just as true today as it was then. In particular, point 9 in the abstract- if trauma is the cause there is plenty of reliable (clinical) medico-surgical evidence. (Clinically, imaging, operative & pathologically.)

See this abstract-

The relation of trauma to inguinal hernia an analysis of 1,376 herniotomies

John J. Moorhead, M.D.

New York City USA

DOI: http://dx.doi.org/10.1016/S0002-9610(40)90146-5

Abstract

1.1. Hernia is never caused by injury; the preformed sac is always an antecedent.

2.2. Hernia can be aggravated by injury if the source and symptoms are adequate.

3.3. Immediate disabling pain is the chief symptom, and this is associated with nausea, tenderness, swelling and other manifestations resembling peritoneal shock.

4.4. At operation, the findings usually denote an ancient process, as indicated by adhesions, extrasaccular and intrasaccular.

5.5. The pathologic examination of the sac demonstrates chronic peritonitis and fibrosis.

6.6. Hernia is a chronic progressive disease, a ptosis, a diverticulum, and not an acute surgical entity except in very rare instances.

7.7. A large proportion of our adult male population have hernia and do not know it; and we, as surgeons, do not know it either, when we are treating them for contiguous injury grave enough to cause aggravation if trauma is a common accelerating factor.

8.8. Like osteomyelitis, once a hernia always a hernia, and it is subject to periods of accession and remission.

9.9. If trauma is to be accused and found guilty, then there is always plenty of reliable evidence. This need never be medicolegally seductive nor speculative, but rather, medicosurgically deductive and positive.

10.10. Trauma has burdens enough without being saddled with this ancient heritage which modern traumatology should cast into the discard along with grape seeds as a cause of appendicitis.

I do not think that a falling down trauma can cause inguinal hernia.The pathophysiology of indirect hernia is the excistance of sac and in the direct one is the weakness of floor of ingiunal canal that is chronic process.

René STOPPA learn me that trauma inguinal hernias are unfrequent if they exist.  More often they are hernias discovered after a traumatism that did exist anteriorly. To accept the trauma origin of a hernia it must be a direct hernia, diagnoses immediatly after the trauma with clinical description of blood infiltrating the skin in front with migration after to scrotum. Nowadays, CT scan is often realised immediatly after a trauma and you might see an infiltration of the abdominal wall in the inguinal area.

In Amiens we never observed an isolated trauma inguinal hernia but we observed some disruption of the abdominal wall in this area associated with iliac bone fracture. I also observed a disruption of a retromuscular prolen prosthesis after a an abdominal wall trauma by a food (policewoman attacked by a man who wanted to escape !). This policewoman had ten years before the resection of a tumor of abdominal wall with regular annual CT scan so we are sure there is a link between the trauma and the incisional hernia.

The point every one is trying to make is that the only way of conclusively showing whether the trauma resulted in a pre-formed sac from becoming clinically evident is if the patient had been examined carefully pre-trauma, to rule out a small hernia. This still happens in the armed forces. Besides that, it will always remain conjecture. However, this is not to deny the fact that given the circumstances of trauma, the characteristics of the individual's abdominal wall and any co-morbidity a preformed sac becoming manifest suddenly is a clinical possibility. 

In medicine, we never say never; and always attempt to use logic; thus keep our minds open to possibilities. Trevor D'Netto provides us with a brilliant summary from the past of the art of observation being applied to the science of statistics. Yet, I would not take as a given anything anyone says, even if they only operated on herniae and performed 100,000 repairs. A rarity is just that - it could happen in case 100,001. That is why there is still value in reporting unusual presentations; if for no other reason than to counter rigid dogma some of us develop. Of course, it is the responsibility of the reporter not to over-call the case. I.e. A first-time presentation of a hernia after trauma is not the same as the trauma causing the hernia; it is an unusual precipitating factor.

I think it is more likely that an inguinal hernia is noticed for the first time after trauma than the trauma causing an inguinal hernia. Of course a direct inguinal hernia may theoretically result from a traumatic injury to the posterior wall of the inguinal canal.

Thank you so much for all your replies. Some pre accident details: female, 63 years old, 2 children aged 28 and 34, 56 kg, BMI 21, very little subcutaneous abdominal fat, extreme active and physically demanding lifestyle, vet nursing, horses, gardening, all requiring heavy lifting, twisting, bending, running, jumping, always engages abdominal muscles when lifting etc., very high abdominal muscle tone, flat abdomen, never smoked, health conscious, very high fibre diet, never constipated, regular bowel movements, never diarrhoea, apart from a couple of injuries not seen GP since 1993. As a vet nurse aware of A&P, no sign of hernia. After fall from galloping horse wedge fractures L1 and L4, Webber A fracture left ankle, massive swelling and bruise right and left buttocks, bruise left elbow, severe pain, unable to move, flat on back. Examination noted abdomen SNT, good bowel sounds. TLSO back brace 7 weeks 24/7, back slab left ankle non-weight bearing 4 weeks. 24 hours post accident abdominal pain, gas, constipation, nausea put down to Codeine side effects. No bowel movements for 7 days, then small nuggets at first, could not strain as could dislodge spinal fractures. When able to take brace off and stand up small 3 x 2 cm right sided inguinal hernia noticed, easily reducible, not visible when lying down, not painful, about 8cm from my groin crease. I cannot find any pictures of a similar one, the only ones I have seen are egg size and near the labia. Mine was not like that, more like a very small sausage tucked in. If I had had any subcutaneous rolls of fat I would not have seen it. I know it was not there before the accident because I would have seen it. As soon as I took the brace off and could bend it was so obvious. I know my body. If anyone wanted to write this up I would be happy to help. Thank you again for your interest. 

I would still suggest examination by a surgeon. This is more likely to be an early incidental hernia, but the position has not been sufficiently defined to be able to differentiate between a direct, indirect or even a Spigelian hernia. A timely MRI could have been contributory to ietiology. The abdominal symptoms do not provide any conclusive pointers. The bed rest, lumbar fractures, child-bearing are all contributory and the lack of local symptoms at the time is a major detractor. Given the history as provided, this does not appear to be a post-traumatic hernia.

Yes and by other sudden deceleration injuries inc car crash, cycling etc

Yes this is a possibility following a sudden blow to the abdomen,  as does acute traumatic appendicitis. 

It is possible; yes, but highly unlikely with the history provided.

I would agree with Drkamal,I have not come across during my 45 yrs of practice.

Interesting discussion, with many well-put comments.

I haven´t either ever seen a groin hernia where a trauma was the established sole etiology.

"No bowel movements for 7 days, then small nuggets at first" to me indicates not a hernia-related sequela, but rather constipation caused by opioids and immobilization.

I think Inguinal hernias can not present as traumatic hernia because trauma(may be due to fall from running horse or fall from certain height or by car accident etc.) results in sudden increase in intra-abdominal pressure and that results in herniation but that is possible only when there is potential space which gets opened up and results into herniation just like in traumatic lumber hernia ( superior and Inferior lumber triangles).

I agree with Dionisios Pinialidis that such hernias can appear only if he has some congenital weakness or some pre existing undiagnosed hernia (bubonocele) otherwise not.

Rarely if ever and if it is happened means it had been unrecognised before the fall and after the fall it had become recognized

A single word answer would be NO

ANYTHING, just ANYTHING can happen after falling a galloping horse !!!!!!!

Caution must be given to this question because we do not have all details of the trauma off the horse. Available informations are:

1- hernia can be caused by preexisting sac (young people)

2- hernia can be caused by weakness of the abdominal wall especially at the lowest wall of inguinal region (elder people)

According to those informations, the second cause could have relation to the trauma if the person had sudden high elevation of abdominal pressure with the trauma or had a direct coup to the abdomen at the moment of the accident.

Hernia cannot form acutely as a result of trauma. To better understand this, I think, pathomorphology of hernia is helpful. A hernia has three elements: hernia gate, hernia sac  and its contents. Hernia sac itself has three parts: the neck, the body and the fundus.

Traumatic injury to abdominal wall, particularly rupture of transverse fascia can lead to the formation of one element of hernia, i.e. hernia gate only, NOT a hernia. In other words, A DEFECT OF ABDOMINAL WALL IS NOT A HERNIA.

Traumatic injury to abdominal wall, particularly rupture of transverse fascia can lead to the formation of one element of hernia, i.e. hernia sac only, NOT a hernia. In other words, A DEFECT OF ABDOMINAL WALL IS NOT A HERNIA.

I meant hernia gate only.

What you are describing is an indirect inguinal hernia. The definition of a hernia, however, I s protrusion of organ/s from within their containing cavity. The protrusion may be internal (e.g. Diaphragmatic) or external (Spigelian/inguinal/femoral etc) Thus, a protruding sac containing viscera, albeit through a traumatic or even iatrogenic defect does amount to a hernia. The debate is whether one can categorically be certain retrospectively if the protrusion occurred as a direct consequence of the trauma. This is what cannot be declared with certainty, unless one observes the area during the acute traumatic phase, preferably with radiological imaging.

Lots of people with pre existing disposition to hernias will describe a traumatic event often involving raised intra and pressure. I could see that a fall would transmit more force than heavy lifting for example

Thank you. Yes the difference between lifting and having a traumatic fall is that when you go to lift you engage your abdominal muscles and so prepare for the lift to prevent a hernia. When you have a fall it happens so fast you are not prepared and so have not engaged abdominal muscles. I think this is particularly important because without the fall you probably would not have had the inguinal hernia. This is extremely important in cases of accidents because where compensation is claimed for injuries, expert medical witnesses say a fall cannot cause an inguinal hernia. This happened to me. Would you be interested in researching and writing a paper about this? I would be most willing to give you my case history. When I was trying to research this I could only find one paper.

Good discussion,Inguinal hernia formation is a process, Fall from a running horse,first produces trauma and later lead to a hernia other wise pre existing weakness usually the cause.

Having said above , accident like in this case can cause any type of injury,in some totally unexpected.

Thank you. I would like to do more research into this.