H
haem iron-containing, oxygen-carrying, red-coloured constituent of haemoglobin
haemarthrosis blood within a joint
haematocrit; Hct percentage, by volume, of cells within a blood sample
haematogenous spread spread of microorganisms via circulating blood
haemoglobin; Hb red-coloured protein within erythrocytes (6% haem; 94% globin); transports oxygen (as oxyhaemoglobin) from lungs to tissues, where oxygen is readily given up and oxyhaemoglobin is reduced to haemoglobin (see glycosylated haemoglobin)
haemolytic causing lysis of red blood cells
haemopoiesis formation and development of blood cells and platelets
haemostasis deliberate arrest of blood flow, e.g. during surgery
haemostat (2) instrument that arrests haemorrhage by applied pressure, e.g. Spencer–Wells forceps
Haglund’s deformity; retrocalcaneal exostosis; pump bump hypertrophy or prominence of posterior superior lateral border of calcaneum; characteristic of earlier Sever’s disease, or chronic mechanical irritation from shoe counter against the heel during gait in a foot that overpronates at the subtalar joint (see compensated rearfoot varus; mobile pes cavus)
Haglund’s syndrome see syndrome, Haglund’s
half-life see radioactive isotopes
hallux abductovalgus; HAV biplanar first-ray deformity, where the tip of the hallux is deviated on the transverse plane (away from body midline) in conjunction with frontal-plane axial rotation of the hallux about its longitudinal axis (i.e. the medial nail sulcus approaches the support surface) and transverse-plane deviation of the first metatarsal head towards the midline of the body (i.e. secondary to metatarsus primus varus); HAV is associated with a range of forefoot pathologies (Table H1 and Box H1; Figure H1) and may require surgical correction (Table H2)
Table H1 Features that predispose to hallux abductovalgus
| Location | Feature | Predisposing factor |
|---|---|---|
| Intrinsic to the foot and lower limb | Excess STJ and MTJ pronation | Ankle equinus Pes planovalgus Forefoot varus Metatarsus primus elevatus Metatarsus primus varus Pes cavus Long second metatarsal/short first metatarsal Functional hallux limitus Adductus foot |
| Structural anomalies within the lower limb that predispose to compensatory foot pronation | External tibial torsion Tibial varum Genu varum/valgum, recurvatum Femoral retroversion Wide-based gait Longer limb | |
| Trauma | First MTPJ intra-articular damage First MTPJ sprain (turf toe) Subluxed second toe Soft-tissue tears | |
| Extrinsic to the foot and lower limb | Inflammatory joint disease | Rheumatoid disease Psoriatic arthropathy Gout |
| Connective tissue disorders characterized by joint hypermobility | Generalized hypermobility syndrome Ehlers–Danlos syndrome Marfan’s syndrome Down’s syndrome Osteogenesis imperfecta | |
| Neuromuscular disease characterized by the development of pes cavus or pes planovalgus | Multiple sclerosis Hereditary sensorimotor neuropathy (Charcot–Marie–Tooth disease) Cerebral palsy Poliomyelitis Friedreich’s ataxia |
STJ, subtalar joint; MTJ, metatarsal joint; MTPJ, metatarsophalangeal joint.
Box H1 Clinical features of hallux abductovalgus
MTPJ, metatarsophalangeal joint; IPJ, interphalangeal joint; PIPJ, proximal interphalangeal joint.
Figure H1 Clinical features of hallux abductovalgus. HD, heloma durum; ID, interdigital; IDH, interdigital heloma. This article was published in Neale’s Disorders of the Foot, Lorimer, French, O’Donnell, Burrow, Wall, Copyright Elsevier, (2006).
Table H2 Surgical options for the treatment of hallux abductovalgus
| Surgical approach | Intervention | Example procedure |
|---|---|---|
| Joint-destructive procedures | Excision of base of hallux proximal phalanx Arthrodesis | Keller Screw arthrodesis |
| Joint-preserving procedures | Closing basal wedge osteotomy, first metatarsal Distal metatarsal osteotomy | Basal wedge osteotomy Wilson; Austin |
| Ray alignment procedures | Z osteotomy Medial closing-wedge osteotomy, hallux | Scarf Akin |
| Ray stabilization procedures | Arthrodesis of first metatarsal/medial cuneiform joint | Lapidus |
| Cosmesis | Excision of medial eminence at head of first metatarsal (cheilectomy) | Silver |
There are over 100 named surgical techniques for the correction of hallux abductovalgus, most of which are modifications of a number of principles of approach.
hallux flexus uniplanar, sagittal-plane first-ray deformity, in which the first metatarsal head is dorsiflexed (metatarsus elevatus) and the hallux proximal phalanx is plantarflexed relative to the support surface; the distal phalanx of the hallux may be in either a neutral or dorsiflexed position
hallux limitus first-ray pathology characterized by restricted dorsiflexion (reduced sagittal-plane motion; i.e. <60° available dorsiflexion) at first metatarsophalangeal joint, during the propulsive phase of gait (Tables H3 and H4 and Box H2, Figure H2; see synovitis)
Table H3 Factors that predispose to hallux limitus/rigidus
| Location | Feature | Characteristics |
|---|---|---|
| Intrinsic factors | Foot shape | Rectus foot Long first toe Long first metatarsal |
| Biomechanical factors within the foot that cause excess STJ and MTPJ pronation, so that foot is pronated from midstance to toe off | Ankle equinus Pes planovalgus Forefoot varus Metatarsus primus elevatus Hypermobile first ray Flexor plate immobility Plantar soft-tissue contracture Functional hallux limitus | |
| Structural anomalies that predispose to excess STJ and MTPJ pronation | External tibial torsion Tibial varum Knee position variants Femoral retroversion Longer limb Wide-based gait | |
| Trauma | Osteochondritis Osteoarthrosis Soft-tissue tears Turf toe | |
| Extrinsic factors | Inflammatory joint disease | Rheumatoid arthritis Gout/crystal arthropathy Psoriatic arthropathy Generalized osteoarthritis Sesamoid degeneration |
| Occupational hazard – repeated forced dorsiflexion of the first MTPJ/stubbing the first toe | Carpet laying En pointe ballet dancing Football Netball Tennis High-heeled shoes |
STJ, supratalar joint; MTPJ, metatarsophalangeal joint.
Table H4 Classification of stage of hallux limitus/rigidus
| Stage | Characteristics |
|---|---|
| Stage 1 Functional HL ∼60° available dorsiflexion at 1 MTPJ | Functional (weight-bearing) limitation of dorsiflexion at 1 MTPJ, with: • 1 MTPJ painful under load • Hypermobility of first ray • No real joint deterioration, but some osteophytosis • Non-weight-bearing 1 MTPJ dorsiflexion near normal |
| Stage 2 Mild structural HL 35–55° available dorsiflexion at 1 MTPJ | Structural limitation of dorsiflexion at 1 MTPJ • 1 MTPJ painful after exercise/movement • Broadening and flattening of 1 MTPJ surfaces • Narrowing of 1 MTPJ space • Moderate osteophytosis of 1 MTPJ area • Local bone sclerosis • Elevation of the first ray • Sesamoid hypertrophy • Reduced 1 MTPJ dorsiflexion (weight- and non-weight-bearing) • Reduced heel lift • 1 MTPJ crepitus |
| Stage 3 Moderate structural HL 15–30° available dorsiflexion at 1 MTPJ | Structural loss of dorsiflexion at 1 MTPJ • Pain within 1 MTPJ • Marked 1 MTPJ deterioration • Loss of 1 MTPJ space • Extensive osteophytosis • Bone sclerosis • Cystic degeneration of subchondral bone • Joint ‘mice’ • Hypertrophy of sesamoids • Elevation of the first ray • Loss of height of MLA • Decreased calcaneal angle • 1 MTPJ crepitus • Marked reduction of heel lift |
| Stage 4 Severe HR <15° available dorsiflexion at 1 MTPJ | 1 MTPJ immobility • 1 MTPJ ankylosis and loss of joint space • Marked osteophytosis and increased bulk of 1 MTPJ • Loss of heel lift and/or hyperextension of IPJ of hallux |
1 MTPJ, first metatarsophalangeal joint; MLA, medial longitudinal arch; IPJ, interphalangeal joint.
Box H2 Gait and postural effects of hallux limitus/rigidus
hallux phalangeus valgus; hallux interphalangeus valgus transverse (or transverse + frontal-plane) deviation of the distal hallux phalanx, at the interphalangeal joint, towards the midline of the foot
hallux purchase the degree of contact achieved between the hallux pulp and the ground surface; a piece of paper should not move when attempting to pull it out from under the weight-bearing hallux pulp (Table H5)
Table H5 Classification of hallux purchase
| Grade | Characteristics |
|---|---|
| Good | The sheet of paper remains static and in situ when pulled |
| Fair | The sheet of paper moves slightly when pulled, but tends to tear when greater traction is applied |
| Poor | The sheet of paper can be pulled out with minimum effort |
| Absent | The paper slips out easily; it is not retained by the hallux as the pulp of the toe does not make ground contact |
Hallux purchase is inferred by the ease with which a sheet of paper can be pulled out from beneath the pulp of the weight-bearing hallux.
hallux rigidus ankylosis or grossly reduced sagittal-plane motion of first metatarsophalangeal joint (i.e. <5° available dorsiflexion); endpoint of progressive hallux limitus (Tables H3 and H4; Figure H3)
hallux valgus uniplanar, transverse-plane first-ray deformity in which the hallux tip is deviated away from the body midline, and the first metatarsal head deviated toward the body midline (Tables H3, H4 and H6); progression of minor hallux valgus may be slowed down or arrested by functional orthoses worn with appropriate shoe wear; surgery may be indicated to reduce major hallux valgus (Table H2)
Table H6 First-ray relationships that inform a diagnosis of hallux abductovalgus (from an anteroposterior-view radiograph)
| Angle | Location | Normal values |
|---|---|---|
| Intermetatarsal angle | The angle between the longitudinal axes of the first and second metatarsals | 8–12° |
| Metatarsus adductus angle | The angle between the longitudinal axes of the lesser metatarsals and the first metatarsal | <15° |
| Hallux abductus angle | The angle between the longitudinal axes of the hallux and the first metatarsal | <20° |
| Proximal articular set angle (PASA) | The comparison of the planes of the articular surfaces of the head of the first metatarsal and the base of the proximal phalanx of the hallux | <7.5° |
| Distal articular set angle (DASA) | The comparison of the planes of the articular surfaces of the head of the proximal and the base of the distal phalanx of the hallux | <7.5° |
| Hallux interphalangeus angle | The angle between the longitudinal axes of the proximal and distal phalanges of the hallux | <10° |
| Medial sesamoid position | The relationship of the medial sesamoid and the head of the first metatarsal | Within the medial groove of the first metatarsal head |
halo naevus melanocytic naevus surrounded by a characteristic ring of amelanotic skin
hamamelis water; witch hazel cooling lotion extracted from witch hazel bark
hamstring tendinitis sports-related injury to hamstring muscle bellies, their tendons or insertions, characterized by tightness and pain in the affected muscle/tendon
hand, foot and mouth disease; orf see disease, hand, foot and mouth
hangnail loose tag of epidermis attached at its proximal end within the medial or lateral nail fold
Hansen’s disease; leprosy see disease, Hansen’s (Tables H7 and H8)
Table H7 Presentations of Hansen’s disease (leprosy)
| Leprosy type | Characteristics |
|---|---|
| Tuberculoid leprosy (TT) or paucibacillary leprosy (PB) | Vigorous host resistance and low infection A localized disease in patients with high cell-mediated immunity characterized by a single, clearly demarcated hypopigmented anaesthetic skin area of the face, hands or feet, with thickening of the subserving nerve |
| Borderline tuberculoid leprosy (BT) | As TT, but more numerous, smaller skin lesions with thickening of peripheral nerves and deformity of the hands and feet |
| Borderline leprosy (BB) | Numerous skin lesions of varying size and form (macules, papules, plaques) with punched-out, hypopigmented anaesthetic centres; widespread nerve involvement and limb deformity |
| Borderline lepromatous leprosy (BL) | Large number of florid asymmetrical skin lesions of variable form, strongly positive to acid-fast bacilli |
| Lepromatous leprosy (LL) or multibacillary leprosy (MB) | Severely compromised host resistance and massive infection Skin changes of the face, earlobes, buttocks, upper and lower limbs, peripheral oedema, rhinitis and loss of the outer one-third of the eyebrows are characteristic of the early stages, with later mucous membrane involvement causing nasal stuffiness, laryngitis and hoarseness, thence nasal septum perforation and collapse of the nasal cartilages (saddle-nose deformity), glove-and-stocking anaesthesia, gynaecomastia, testicular atrophy, ichthyosis, nerve palsies and neurotrophic resorption of the phalanges. Lucio’s phenomenon (endarteritis and ulceration) is noted in Mexico and Central America |
Table H8 Lower-limb involvement in Hansen’s disease
| Disease effect | Clinical symptoms |
|---|---|
| Sensory anaesthesia | Painless trophic plantar ulceration along the lateral plantar border of the foot, of apical tissues, second metatarsophalangeal joint, pulp and interphalangeal joint area of the hallux |
| Motor paralysis | Intrinsic muscle paralysis causing claw-toe formation and anterior drift of the plantar fat pad, with relative exposure of the plantar aspects of the metatarsophalangeal joints to abnormally high plantar pressures Extrinsic muscle paralysis, i.e. paralysis of the anterior and peroneal muscles of the lower leg with footdrop and hindfoot inversion and the development of trophic ulcers along the lateral border of the foot |
| Autonomic neuropathy | Loss of sweat gland function with dry skin and fissure Compromised superficial and deep arterial circulation due to loss of control of arteriolar sphincters, so that, although the skin and superficial tissues are warm, skin perfusion is reduced and there is a greater than normal flow of blood through bone (bone hyperaemia) leading to osteoporosis, bone resorption and pathological fracture |
| Tarsal disintegration | Infiltration of the foot bones with bacilli, causing rarefaction of cancellous bone, fracture of tarsal bones followed by profuse recalcification with loss of normal bony architecture Hyperaemia-related osteoclastic resorption of bone |
| Osteoporosis and osteomyelitis | Absorption of phalanges and pathological fractures of affected bones in neuropathic and immobile feet |
hard corn see heloma durum (plural: helomata dura); see Table C14
Harris and Beath mat rubber mat formed of intersecting squares with walls of varying heights, used to achieve a dynamic record of plantar pressures; the mat is inked and covered with a sheet of paper and the patient walks barefoot across the paper; areas of highest plantar pressure show as areas of increased density of ink when the paper is peeled off the mat (see Table G2)
Harris–Beath projection radiographic projection of the foot, to visualize rearfoot and tarsus; the patient is positioned with the foot flat to the support surface, ankle joint dorsiflexed and knees flexed (as if preparing for a standing jump); the X-ray beam is directed at the posterior aspect of the ankle joint, at an inclination angle of 35–45° (see Table R1)
HbA1C see glycosylated haemoglobin
HC45 topical emollient cream containing 1% steroid; see corticosteroid
HDL see high-density lipoprotein cholesterol
HDN see haemolytic disease of the newborn
healing process of restoration of tissue integrity
healing agents topical agents promoting healing and healthy granulation
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