Lunate pathology mimicking Kienbock's Disease; defining the disease and exploring differentials

Abstract

Kienbock's Disease is a rare disease with insidious clinical symptoms and characteristic features on imaging. However, the clinical and radiological findings are similar to many other pathologies affecting the lunate. We present a precise definition of the Kienbock's wrist, and an overview of other pathologies affecting the lunate. Better understanding of the clinical, radiological and arthroscopic findings of these diseases, allows accurate diagnosis and effective management strategy.

1. Defining the Kienbock's wrist

Our understanding of the Kienbock's patient has evolved with our understanding of the disease. The mantra; ‘male, middle-aged, manual worker’ has been historically used to describe the typical Kienbock's patient, with characteristic clinical and radiological findings.1, 2 We know, however, that the disease affects a spectrum of ages, gender and occupations and may therefore present atypically. As surgeons, our management algorithms are often focused on a diagnosis of Kienbock's Disease when we identify pathology in the lunate on imaging. It is therefore imperative to develop a firm understanding of the characteristics of the Kienbock's wrist, but equally, to appreciate other pathology which can mimic KD either clinically or radiologically, as other pathology can also cause focal osteonecrosis in the lunate leading to collapse or arthrosis. An important concept to recognize is that although the etiology is debated, Kienbock's Disease is a disease affecting four fundamental elements: chondral, osseous, vascular and ligamentous structures. Using advanced radiology and arthroscopy, pathological changes in these structures can be assessed to determine an accurate diagnosis and help guide management

1.1. Clinical presentation

KD has been reported in all groups but typically affects young adults to middle-aged. The male:female ratio is 2:1². Some patients attribute symptoms to a defined episode of trauma, but usually symptoms are insidious in nature.

There is not one typical pain location. Patients report a generalized discomfort – often centrally in the wrist. Ulnar-sided pain is not uncommon however and may relate to ulnar-sided impingement due to carpal collapse and ulnar translocation in later stages of the disease. Volar discomfort or mechanical symptoms can occur, particularly with flexion and may relate to hinging of the volar horn of the lunate on the distal radius following lunate fracture.³

1.2. Characteristics of the Kienbock's wrist

Carlos Irisarri and Greg Bain identified that there are a series of anatomical risk factors and biological conditions that may predispose to Kienbock's disease (Fig. 1). Some of these are rare and may overlap (eg vascular disorders and genetic conditions). It can be difficult to determine which disease processes are associated with Kienbock's Disease, or a more localized osteonecrosis of the lunate secondary to the primary pathology.5, 6, 7, 8, 9, 10 We have placed these factors into a table, to make it easier to interpret¹¹ (table one).

Fig. 1.

Characteristic ‘at-risk’ features of the Kienbock's wrist. Copyright Greg Bain.

Typically, KD affects patients with negative ulnar variance, a Viegas type 1 lunate (one facet for the capitate), with reduced coverage on the ulnar edge of the radius.¹² The lunate is small, trapezoidal (Zapico type 1) and point-loaded between the ulnar edge of the capitate and radius.¹ Biomechanically, this lunate is therefore “at-risk” for high mechanical stress, and we postulate that this is likely to attribute to stress fracture propagation (Fig. 2).¹³ Although the coronal fracture was originally described as the classic pattern in KD, we have found a similar prevalence of sagittal fractures – propagating longitudinally along this line of stress (Fig. 3).¹⁴ Dynamic CT study in the KD wrist shows this sagittal fracture to hinge on this fulcrum with wrist radial and ulnar deviation.¹⁵

Fig. 2.

The KienBOX lunate. (a) The lunate is a BOX shape, with significant forces transmitted through it. With wrist motion the lunate cantilevers on the lunate facet. In the “at risk wrist”, there may be a fracture of the 0.1 mm single layer subchondral bone plate, at the tipping point. (b) The fracture propagates through the trabeculae, adjacent to the proximal subchondral plate, creating the crescent fracture. The sagittal fracture propagates distally. The coronal fractures are created by the coronal “nutcracker” fracture is created by the capitate impacting on the distal lunate articular surface (Copyright Greg Bain, 2022).

Fig. 3.

Sagittal fracture lines in two patients (a) and (b). The fracture line propagates from the ulnar edge of the radius towards the ulnar aspect of the capitate, indicating point-loading in this area between the capitate and radius; the “nutcracker” effect (white arrow). On dynamic 4D CT imaging, the impaction point on the proximal lunate can be clearly visualized (yellow arrow). Copyright Greg Bain and Simon MacLean.

1.3. Phenotypes of Kienbock's disease

There is a spectrum of patients that present with Kienbock's disease occurs in a spectrum of patients and is not a disease exclusive to the ‘middle aged male manual worker’.¹⁶

• •Young “Teenbock” patient, self-limiting disease.¹⁷
• •Middle-aged (20–40) male manual worker with a negative ulnar variance.
• •Older female patient with positive ulnar variance.

1.4. Radiographic

Radiographs in the early stages of the disease are normal and may develop lunate sclerosis, and progress to fractures, fragmentation and collapse. Characteristic fractures are the template fracture – which is the impaction fracture of the radius on the proximal lunate. The coronal “nutcracker” fracture extends from the radiocarpal to the midcarpal joint.

Finally, the sagittal fracture extends from the ulnar border of the lunate, towards the capitate. The lunate will become flattened and widened as fractures occur and the bone collapses. The fractures and the collapse are predominantly on the radial side of the lunate.

Proximal carpal row collapse and compensatory scaphoid flexion occurs. Collapse is complex and sagittal alignment may reveal DISI-type or VISI-type deformity depending on the instability pattern and the equilibrium in the proximal carpal row. Carpal malalignment is a result of avulsion fracture and dissociation of intrinsic perilunate and extrinsic radiolunate ligaments (Fig. 4).

Fig. 4.

(a) Ulnotriquetral impingement causing ulnar-sided wrist pain in a patient with advanced Kienbock's disease (white arrow). (b) Volar radioulnar impingement due to displacement of the volar horn of the lunate following lunate fracture (yellow arrow). Copyright Greg Bain and Simon MacLean.

Ulnar translocation occurs in later stages of the disease as a result of (1) scapholunate ligament avulsion with diastasis or (2) carpal collapse with insufficiency or ‘pseudo-laxity’ of extrinsic ligaments (Fig. 5).

Fig. 5.

Ulnar translocation in advanced Kienbock's Disease. Taleisnik type 1 (failure of extrinsic stabilizers and type 2 (secondary to scapholunate ligament rupture and secondary stabilizers). Copyright Greg Bain and Simon MacLean.

The articular cartilage is typically involved after the collapse of the subchondral bone plate. Once this occurs, then degenerative arthritis occurs in the radiolunate and lunocapitate joints. When the radial column collapses, STT joint osteoarthritis commonly occurs.^14,15 Radioscaphoid arthritis is rare in KD.

1.5. Advanced imaging

1.5.1. CT: 3-D and 4-D

CT is the gold standard for evaluating the osseous detail of the lunate and wrist. Occult fractures and subchondral bone plate integrity can be examined. Compared with the classical ‘coronal fracture’, we have found a similar prevalence of proximal subchondral bone plate fracture, avulsion fractures of the scapholunate and lunotriquetral ligaments and sagittal fractures. Distal subchondral bone plate fracture is the least common fracture sub-type (Fig. 6).¹⁴

Fig. 6.

Common fracture types in Kienbock's Disease in four different wrists. (a) Sagittal fracture. (b) Proximal and distal subchondral bone plate fractures. (c) Ligament avulsion - lunate attachment of scapholunate ligament. (d) Coronal fractures on plain radiograph often also include proximal subchondral bone plate fracture on CT scan. Copyright Greg Bain and Simon MacLean.

1.5.2. MRI

Alteration in signal in the majority of the lunate is highly suggestive but not pathognomonic of a diagnosis of KD, with a high-signal appearance in T2-weighted images and low-signal in T1 weighted images in the early stages of the disease. As the disease progresses to necrosis, repair and remodelling phases, there is a further decrease in signal in both T1-and T2-weighted images.¹⁸ To further assess vascularity, gadolinium contrast can be used.¹⁹ Other conditions can also cause marked alteration in signal however as outlined further in this review.

1.6. Arthroscopic examination

KD typically has generalized synovitis at arthroscopy. Ballottement of the chondral surfaces is an important part of determining “functional” potential of the articulation. When the wrist is placed into traction, and the proximal chondral surface of the lunate is balloted, the surface will appear to float on compression in the presence of subchondral bone plate collapse. Fractures may be visible and can be palpated with a probe.20, 21, 22, 23 (see Table 1)

Table 1.

Anatomical risk factors and biological conditions that may predispose to Kienbock's disease or avascular necrosis.

Individual	Male
	Age 20–40
	Dominant wrist
	Manual worker
Radius	Negative ulnar variance
Ulnar	Type 1 (Viegas)
Lunate	Type 1 (Zapico)
	Small lunate
	‘Uncovered’ lunate
	Single artery
Genetic	Familial
Vascular disorders	Raynaud's phenomenon
	Sickle cell disease
	Systemic Lupus Erythematosus
	Scleroderma
Metabolic	Gout
Neurological	Cerebral palsy
Medication	Chronic steroid use
Environment	Caisson disease

2. Other diagnoses

There are many disorders that can mimic Kienbock's disease (Table 2). Differentiating pathology in the lunate can be a challenge. It is important to consider that traumatic conditions can cause a transient ischaemia to the lunate, and osteonecrosis of the lunate can be caused by other disease processes.²⁴ Clinical and radiological features can overlap considerably and there may be no one pathognomonic sign. MRI is an important diagnostic tool in KD. Altered signal on T-2 and low signal on T-1 sequences can however be seen in other conditions. The extent of lunate involvement can be overestimated on MRI since abnormal marrow signal may represent reactive granulation tissue and marrow edema.²⁵ We will now outline the other conditions which can masquerade as KD.

Table 2.

Comparison of common lunate pathology mimicking Kienbock's Diseas.

Diagnosis	History	Examination	Radiographs	CT	MRI	Arthroscopy	Key difference to Kienbock's Disease
Kienbock's Disease	Gradual onset pain, swelling, Late: stiffness	Tenderness over carpus, swelling, Late: reduced ROM	Progressive changes; normal, increased density lunate, fractured lunate, lunate collapse, proximal row instability (CIND), Late: arthrosis, ulnar translocation carpus	Increased radiodensity lunate, single fracture line lunate Late: coronal/sagittal/comminution, proximal/distal SCBP collapse	Reduced signal on T-1 sequences, increased signal on T-2 sequences	Generalized synovitis, chondromalacia, perilunate ligament injuries Late: Floating chondral surface, arthrosis
Intraosseous ganglion	Gradual onset pain, swelling, ROM usually normal	May be normal	Discrete or multiple cystic lesions Late: fracture and lunate collapse	Cysts Late: trabecular disruption	Geographical high signal on T-2 sequences and low signal on T-1 sequences	There may be localized synovitis adjacent to lunate Usually no chondromalacia present Late: fractured lunate and arthrosis	Diagnosis usually obvious based on plain radiographs and advanced imaging Even in cases of collapse, homogenous alteration in MRI signal uncommon
Ulnocarpal abutment	Insidious onset or post-traumatic central or ulnar-sided pain Activity-related	Foveal tenderness Positive ulnar carpal stress test Reduced ulnar deviation	Static or dynamic positive ulnar variance Sclerosis ± cystic change proximal ulnar edge lunate ± ulnar head Late: ulnocarpal arthrosis	Sclerosis lunate/ulnar head Cystic change	Central TFCC thinning or tear, Edema proximal ulnar edge lunate ± ulnar head Late: arthrosis, LTL tear	Ulnar-sided synovitis, central TFCC tear Chondromalacia, chondral tear lunate Late: ulnocarpal arthrosis	Even in advanced cases, radial edge of lunate usually spares signal alteration on MRI. Ulnar-sided lunate pathology on arthroscopy, corresponding TFCC central tear
Fracture	Single traumatic event Hyper-extension and axial loading	Swelling, deformity, tenderness	Soft tissue swelling Fracture may not be visible Carpal malalignment, dislocation, fracture to lunate ± other carpal bones	Fracture commonly coronal (volar horn), ± fractures to other carpal bones	Edema to fracture site/bone, intrinsic and extrinsic ligament injuries	Perilunate ligament injuries, comminution common, chondral envelope usually intact to lunate	History of obvious traumatic event, other associated carpal injuries as usually occurs in setting of greater arc injury
Enchondroma	Insidious onset pain	Generalized tenderness ± swelling	Well-demarcated radiolucent lesion		Geographical low signal lesion on T-1 and high signal on T-2 sequences		Radiological findings
Primary radiolunate arthritis	Progressive pain, swelling and stiffness	Tenderness over radiolunate joint	Narrowing of the radiolunate joint, sclerosis and cystic change may be present		Focal edema in the proximal lunate and distal radius lunate fossa	Chondromalacia/full thickness chondral loss in proximal lunate/distal radius lunate fossa	Radiographic arthrosis in KD usually follows instability and lunate fracture
Osteoid osteoma	Progressive pain, worse at night, relieved with NSAIDs	Often normal Swelling, tenderness and reduced ROM can occur	Lesion usually in cortex. Diffuse osteosclerosis with a central radiolucent nidus.	Cortical low-density area with central nidus and surrounding osteosclerosis	Non-specific changes; edema on T-2 sequences and synovium, periostitis	Localized synovitis near lunate, local chondromalacia lunate may be present	Radiological findings

2.1. Intraosseous ganglion

2.1.1. Clinical

Ganglion cysts of the lunate can occur at any age although are commonest in the second and fourth decades.²⁶ Etiology is debated but cystic change may relate to intraosseous degeneration or synovial herniation into the lunate.²⁶ They are often diagnosed incidentally on plain radiographs. In symptomatic patients, pain is insidious with occasional bouts evolving to more constant pain with activity. Wrist swelling can occur, especially with large or multiple cysts. Patients with fracture through the cysts or subsequent degeneration may present with more severe pain or arthritic symptoms. Patients in rare cases may have bilateral symptoms.

2.1.2. Imaging

Radiographs may show discrete or multiple cystic lesions throughout the lunate and surrounding carpal bones. The cyst has a cortical margin that communicates with the scapholunate or lunotriquetral joint. Fracture of the cyst wall and lunate collapse is rare but can lead to arthritic changes in the central column, that can then mimic KD. MRI only shows geographical high signal on T-2 and low signal on T-1 in the area of cystic change in contrast to the homogeneous signal change seen in KD (Fig. 7).

Fig. 7.

Bilateral wrist radiographs of a 25-year-old male farmer. Left wrist (a) and (b) – asymptomatic. Right wrist (c) and (d) showing fracture and collapse of the lunate. Significant pain and weakness. Copyright Simon MacLean.

2.1.3. Arthroscopy

In the majority of cases, the chondral envelope appears intact. Fluoroscopy is essential to identify the cystic lesion. Fluoroscopic guided drilling confirms cystic contents, after which bone grafting and a temporary lunate unloading procedure can be performed (Fig. 8).²⁷

Fig. 8.

Arthroscopic and fluoroscopic-guided decompression, bone grafting and temporary scaphocapitate pinning for symptomatic intraosseous ganglion in the lunate. (a) Localization with needle. (b) Arthroscopic sheath and trochar entry. (c) The trochar is removed and defect packed with bone graft. (d) Two scaphocapitate wires are used to protect the central column whilst the graft integrates. C

2.2. Ulnar carpal abutment

2.2.1. Clinical

Ulnar carpal abutment is a common cause of wrist pain and presents in early middle age onwards in both sexes. It is generally a gradual onset condition, although the patient may consider a single event and a traumatic cause for the onset of symptoms. The condition is caused by positive ulnar variance, which can be primary or secondary to distal radius fracture malunion or less commonly – longitudinal instability of the forearm.

The patient may complain of activity-related pain often ulnar-sided or centrally. Mechanical symptoms with a ‘click’ or ‘snap’ may be reported.

Prominence of the ulnar head may be seen on inspection. Tenderness at the ulnar fovea with pain reproduced on axial loading, rotation and ulnar deviation of the wrist is common.

2.2.2. Radiological

Radiographs may be normal. If the clinical diagnosis is suspected, then radiographs with clenched fist and protonation may show a dynamic positive ulnar variance. Sclerosis or cysts in the ulnar proximal edge of the lunate are common. Corresponding abutment lesions in the distal ulna head may be present. In advanced cases, the lunate may appear radiodense, and MRI may show a more florid edema picture, mimicking KD – with occasionally 80–90 % of the lunate involved with only the radial margin spared. MRI may show thinning and usually central TFCC tearing. Corresponding edema of the ulnar head may be present (Fig. 9).

Fig. 9.

Ulnocarpal abutment. (a) Note the increased radiodensity of the lunate on plain imaging. (b) MRI showing marked increased signal on MRI T2-sequences. Note the relative sparing of the radial portion of the bone. A central TFCC tear is present. (c) Classic arthroscopic findings viewing through the 3/4 portal of advanced ulnocarpal abutment with a central TFCC tear (white star) and full thickness chondral loss on ulnar head and ulnar edge of lunate. The probe sits under the peripheral portion of the TFCC. Copyright Simon MacLean.

2.2.3. Arthroscopy

Common findings include ulnar-sided synovitis. The TFCC usually has a central tear with degenerate margins, and there will be a corresponding lesion on the lunate of chondromalacia, chondral flap, or in advanced cases – exposed subchondral bone.

Unlike KD, generalized synovitis is uncommon. In advanced cased, lunotriquetral ligament tears can be identified.

2.3. Fracture

2.3.1. Clinical

Lunate fracture usually occurs as a spectrum of a greater arc injury in association with a hyper-extension and axial load force, with resultant fracture-subluxation or fracture-dislocation of the carpus.^28,29 Low energy injuries are more likely to result in subluxation, with higher-energy injuries causing associated dislocation of the carpus. Patients usually present with significant pain, swelling and often in the setting of polytrauma. There is a clear history of acute trauma, and clinical differentiation from KD is usually obvious in this scenario.

2.3.2. Radiological

On plain radiographs, soft tissue swelling is invariable present. The fracture plane may be occult on plain films but is well defined on CT scan. There may be associated carpal malignment or dislocation, with fractures to the scaphoid, triquetrum, capitate or radial styloid, representing a “Translunate arc”.²⁸ The fracture is commonly coronal, usually situated in the volar horn.³⁰ Some cases of wrist trauma may present as lunate contusion only on MRI, with increased signal on T2-weighted images (Fig. 10).³¹

Fig. 10.

(a) Traumatic lunate fracture – note the hyper-extension combined with axial load causing a dorsal translunate great arc dislocation. (b) Post-reduction sagittal CT imaging showing a fracture through the proximal capitate and volar horn of the lunate. (c) Another patient presenting with wrist pain and stiffness following chronic trauma; sagittal CT showing non-union volar horn with surrounding arthrosis. Copyright Greg Bain and Simon MacLean.

2.3.3. Arthroscopy

Arthroscopy may reveal associated fractures to other carpal bones, and perilunate ligamentous injuries. Comminution may be seen. Often the chondral envelope is preserved without subchondral collapse, in contrast to arthroscopic examination in advanced cases of KD that may reveal a “floating chondral surface”.⁴

2.4. Radiolunate arthritis

2.4.1. Clinical

Clinical presentation can be similar to KD with gradually progressive pain, swelling and stiffness, with or without history of previous trauma. The patient is tender on palpation of the radiolunate joint with reduced range of motion.

2.4.2. Radiological

Narrowing of the radiolunate joint on radiographs is common and cystic change can be seen. In advanced cases, findings can mimic advanced stages of KD with irregularity of the proximal subchondral bone plate. MRI shows focal edema in the proximal lunate and corresponding articulation of the distal radius (Fig. 11).

Fig. 11.

Radiolunate osteoarthritis. (a)Plain radiographs showing narrowing of the radiolunate joint (b)MRI T-1 sequences showing low signal area in the proximal lunate and corresponding lunate fossa. (b) T-2 sequence showing localized high signal and cystic change. Copyright Simon MacLean.

2.4.3. Arthroscopy

Full thickness chondral loss in the proximal lunate is usually seen in the later stages of KD. In radiolunate arthritis there will be corresponding chondral loss in the lunate fossa of the radius. Synovitis is less generalized.

2.5. Rheumatoid arthritis

The wrist is the most commonly affected joint in rheumatoid arthritis, with synovitis causing rupture of the scapholunate ligament and collapse of the radial column.³² Attenuation of the ulnar collateral ligament of the wrist leads to carpal supination and ulnar translocation.³³ Ulnocarpal impaction can result from translocation and dorsal dislocation of the ulna (caput ulnae syndrome). Arthrosis of the radioscaphoid and radiolunate joints are common. Degeneration and erosion can lead to collapse of the lunate and radiolunate arthritis – similar to the advanced stages of KD (Fig. 12).

Fig. 12.

Advanced rheumatoid arthritis in the wrist. Note the proximal row collapse, with advanced radiocarpal and midcarpal arthritis with lunate collapse. Copyright Greg Bain.

3. Rarer mimics of Kienbock's disease

3.1. Osteoid osteoma

3.1.1. Clinical

Osteoid osteoma is rare in the carpal bones is rare. This benign lesion is osteoblastic in the carpus. It t, typically occurring in children and young adults, with a male: female ratio of 2:1.³⁴ Clinical presentation is often delayed and night symptoms, relieved with non-steroidal anti-inflammatory medication is typical. There are often no specific clinical signs present, although generalized tenderness over the carpus, with swelling and restriction in motion can occur.

3.1.2. Radiological

The lesion is often identified on plain radiographs as an area of diffuse osteosclerosis with a central radiolucent nidus. The lesion is usually situated in the cortex of the bone. MRI is non-specific, with a miss rate of up to 35 % and is generally regarded as inferior to CT for diagnosis.³⁵ Edema on T-2 weighted sequences in the lunate bone marrow and surrounding synovium, and periostitis may be present, mimicking an infectious or malignant process.^36,37 Unlike KD, homogenous alteration in lunate signal is not common. CT is regarded as the gold standard for diagnosis and usually shows a juxta-cortical low-density area with central nidus and surrounding osteosclerosis. In advanced cases, or following surgical excision and curettage, fracture and collapse of the lunate can occur – mimicking KD (Fig. 13).^37,38

Fig. 13.

(a) CT scan showing the nidus within the lesion in the lunate. (b) MRI showing low signal on T-1 sequences in the lesion. Reproduced with permission from Güner, M. D., Kamburoğlu, H. O., Bektaş, U., & Ay, Ş. (2015). Osteoid osteoma of the lunatum mimicking Kienböck's disease. Case Reports in Plastic Surgery and Hand Surgery, 2 (1), 19–21.3.⁴⁵.

3.1.2.1. Arthroscopy

When viewing the radiocarpal and midcarpal joints, there is often a localized synovitis and, adjacent to the lunate will be present. There may be chondromalacia adjacent to the lesion, but in early cases this does not involve the entire chondral surface. In late case of fracture or collapse, there may be more generalized chondromalacia to the lunate.

3.2. Enchondroma

3.2.1. Clinical

Enchondromas are benign medullary cartilaginous neoplasms, more common in tubular bones, and rarely found in the carpal bones.³⁹ Pain is of insidious onset and may be worsened with activity. Swelling and generalized tenderness can occur, but movement is rarely restricted.

3.2.2. Radiological

Radiologically, the disease can be easily differentiated from KD. Radiographs show a well-demarcated radiolucent lesion with a narrow zone of transition. MRI shows a low signal geographical lesion on T1-weighted and high signal lesion on T2-weighted sequences.

3.3. Bone island in the lunate

Bone islands are a common benign sclerotic bone lesions usually representing an incidental finding that occur anywhere in the skeleton. A radial-side bone island in the lunate can mimic Kienbock's disease. On plain radiographs and T1-weighted MR images there is a typical focal sclerotic density. On MRI there is a hypointense lesion on T1-weighted image, a low signal intensity on T2-weighted images. There is no surrounding edema. There is also well-defined spiculation, which are trabeculae entering into the bone island.⁴⁰

3.4. Tuberculosis of the lunate

Dharmshatku presented a case report of a 65 year old female presenting with insidious onset of central wrist pain and stiffness.⁴¹ Radiographs showed an abnormally shaped lunate with sclerosis and a working diagnosis of KD was made. MRI confirmed abnormal signal in both lunate and distal radius with multiple erosions, soft tissue collection and flexor tenosynovitis. PCR of synovial fluid showed the presence of mycobacterium tuberculosis.

3.5. Lunotriquetral coalition

Carpal coalition is rare (0.08–0.13 %) often asymptomatic and discovered incidentally. Fibrocartilaginous coalitions can be symptomatic, and a cause for further investigation. Plain radiographs show joint space narrowing, subchondral cysts and sclerosis of the lunotriquetral joint. T-2 weighted MRI shows edema and cysts in each bone (Fig. 14).⁴²

Fig. 14.

(a) Plan radiographs, (b) MRI showing partial capitohamate and lunotriquetral coalitions and (c) CT scan showing narrowed proximal lunotriquetral joint and adjacent intraosseous cysts. Reproduced with permission from Chiri W, Bain GI (2022). Arthroscopic Resection of Lunotriquetral Coalition. Arthroscopy Techniques. 4 (11); e491-495.

3.6. Giant cell tumour of the lunate

Fitzpatrick presented a case report of a 28-year-old with a 3-year history of pain in the wrist, with marked swelling and tenderness of the carpus. Radiographs showed a lunate collapse but with absence of sclerosis seen in KD. Histology reveals characteristic multinucleated giant cells throughout a uniform stroma of mononuclear ovoid cells.⁴³ This can now be managed with denosumab, which is a monoclonal antibody.

3.7. Metastatic tumors

A systematic review of metastatic conditions of the hand identified 11 metastatic lesions within the lunate.⁴⁴ It was more common in males (65 %), with a mean age of 60 years. And often a known malignancy. Common primary cancers were lung, kidney, thyroid and liver. Any metastatic condition should be managed with an oncologist and include a biopsy to confirm the diagnosis.

4. Discussion

Many wrist pathologies with the insidious onset of pain and swelling and there may be considerable overlap in the clinical and radiological presentation of a range of conditions that affect the lunate. Differentiation of conditions presenting like Kienbock's Disease may be determined by a range of modalities; clinical presentation, imaging, arthroscopy, and in some cases - biopsy. Depending on the nature of the pathology, all modalities may be required. In some cases when advanced imaging is equivocal, only arthroscopic examination may be diagnostic. A summary of the key differences between each pathology and Kienbock's Disease is displayed in table two.

Ethical approval

No ethical approval was required for this study.

Patients consent

There was bo submitted information that can be used to identify patients.

Generative-ai

AI and AI-assisted technologies were NOT used in this manuscript.

Funding

The authors received NO financial support for the preparation, research, authorship, and/or publication of this manuscript.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.