Some dislocation fixes/adjustments.

code/modules/mob/living/carbon/human/human_attackhand.dm

@@ -308,7 +308,7 @@
 	if(!target_zone)
 		return null
 	var/obj/item/organ/external/organ = get_organ(check_zone(target_zone))
-	if(!organ || organ.is_dislocated() || organ.dislocated == -1)
+	if(!organ || (organ.dislocated == 2) || (organ.dislocated == -1))
 		return null
 	var/dislocation_str
 	if(prob(W.force))

code/modules/mob/living/carbon/human/human_organs.dm

@@ -70,12 +70,12 @@
 
 	for(var/limb_tag in list("l_leg","r_leg","l_foot","r_foot"))
 		var/obj/item/organ/external/E = organs_by_name[limb_tag]
-		if(!E)
-			stance_damage += 2
-		else if (E.status & ORGAN_DESTROYED)
+		if(!E || (E.status & (ORGAN_DESTROYED|ORGAN_DEAD)))
 			stance_damage += 2 // let it fail even if just foot&leg
-		else if (E.is_malfunctioning() || (E.is_broken() && !(E.status & ORGAN_SPLINTED)) || !E.is_usable())
+		else if (E.is_malfunctioning() || (E.is_broken() && !(E.status & ORGAN_SPLINTED)) || (E.status & ORGAN_MUTATED))
 			stance_damage += 1
+		else if (E.is_dislocated())
+			stance_damage += 0.5
 
 	// Canes and crutches help you stand (if the latter is ever added)
 	// One cane mitigates a broken leg+foot, or a missing foot.
@@ -102,7 +102,7 @@
 		if(!E || !E.can_grasp || (E.status & ORGAN_SPLINTED))
 			continue
 
-		if(E.is_broken())
+		if(E.is_broken() || E.is_dislocated())
 			if(E.body_part == HAND_LEFT)
 				if(!l_hand)
 					continue

code/modules/mob/living/carbon/human/life.dm

@@ -389,7 +389,7 @@
 		// Lung damage increases the minimum safe pressure.
 		if(species.has_organ["lungs"])
 			var/obj/item/organ/lungs/L = internal_organs_by_name["lungs"]
-			if(!L)
+			if(isnull(L))
 				safe_pressure_min = INFINITY //No lungs, how are you breathing?
 			else if(L.is_broken())
 				safe_pressure_min *= 1.5

code/modules/organs/organ_external.dm

@@ -96,9 +96,14 @@
 		dislocated = 0
 	if(children && children.len)
 		for(var/obj/item/organ/external/child in children)
-			child.undislocate()
+			if(child.dislocated == 1)
+				child.undislocate()
 	if(owner)
 		owner.shock_stage += 20
+		for(var/obj/item/organ/external/limb in owner.organs)
+			if(limb.dislocated == 2)
+				return
+		owner.verbs -= /mob/living/carbon/human/proc/undislocate
 
 /obj/item/organ/external/update_health()
 	damage = min(max_damage, (brute_dam + burn_dam))
@@ -837,7 +842,7 @@ Note that amputating the affected organ does in fact remove the infection from t
 	return 0
 
 /obj/item/organ/external/proc/is_usable()
-	return !(status & (ORGAN_DESTROYED|ORGAN_MUTATED|ORGAN_DEAD))
+	return !is_dislocated() && !(status & (ORGAN_DESTROYED|ORGAN_MUTATED|ORGAN_DEAD))
 
 /obj/item/organ/external/proc/is_malfunctioning()
 	return ((status & ORGAN_ROBOT) && (brute_dam + burn_dam) >= 10 && prob(brute_dam + burn_dam))