Posttraumatic Carpal Instability Nondissociative

Abstract

Background  Posttraumatic midcarpal instability nondissociative (CIND) is an exceptional rare condition, therefore the outcome after different treatment options remains unknown.

Questions  The purpose of this study was to investigate the different treatment options for posttraumatic CIND. We also describe the different radiological and magnetic resonance imaging (MRI) findings in this patient cohort.

Patients and Methods  We present outcomes of 10 patients who developed CIND following acute wrist trauma between 2007 and 2018, 3 with dorsal intercalated segment instability pattern (CIND-DISI) and 7 with volar intercalated segment instability (CIND-VISI) radiographically.

Results  Three patients with CIND-VISI had satisfactory outcomes with conservative treatment. Two patients with irreducible CIND-DISI and one with CIND-VISI underwent proximal row carpectomy (PRC), two with reducible CIND-VISI had radiolunate fusion, and two with secondary osteoarthritis had total wrist fusion. All patients with CIND-DISI needed surgery, whereas only four of the seven patients with CIND-VISI needed surgery. On MRI, all three patients with CIND-DISI had rupture of the radiolunate ligament.

Conclusions  The data collected in this study may provide the first step toward better understanding of the pathology for this exceptionally rare finding. In CIND-VISI, we have not seen any ligament injury in four patients. Therefore, conservative therapy is more likely to be the first step. In CIND-DISI, we recommend an operative procedure: if detected early, with ligament suture, otherwise by radiolunate fusion, PRC, or total wrist fusion.

Level of Evidence  This is a Level IV study.

There are four major patterns of carpal instability: carpal instability dissociative (CID), when there is a derangement between the bones of the same carpal row; carpal instability nondissociative (CIND), when no disruption exists between bones of the same row, but there is dysfunction between the radius and the proximal row or between the proximal row and the distal row; carpal instability complex, when there are both CID and CIND; carpal instability adaptive, such as a malunited distal radius fracture, which has induced an adaptation of the proximal carpal row. ^{1 2 3}

CIND is divided into four major types: CIND-volar intercalated segment instability (CIND-VISI, or palmar CIND), CIND-dorsal intercalated segment instability (CIND-DISI, or dorsal CIND), combined CIND, and adaptive CIND. ⁴ The combined CIND demonstrated CIND-VISI in addition to a positive dorsal capitate-displacement test. The CIND after an intra-articular distal radial fracture has been reported but without the documentation of magnetic resonance imaging (MRI) findings. ^{5 6 7} The purpose of this study was to describe MRI findings and surgical treatments of 10 patients presenting with DISI and VISI following acute wrist trauma, including 3 patients suffering from a distal radial fracture.

Patients and Methods

Between January 2007 and August 2018, we identified 11 patients with posttraumatic CIND, based on the radiographic findings. This study was approved by the local ethics committee, and all patients provided written informed consent for their data to be used for our analysis. CIND-VISI was defined in cases where the radiolunate angle was greater than 15 degree on standard lateral X-rays, and CIND-DISI where it was less than –15 degrees. ⁸ Baseline data were retrospectively extracted from patient records and included details of the diagnosis, MRI findings regarding ligament lesions, and the date and type of surgery undertaken ( Table 1 ). All MRI consisted of pulse sequences in three orthogonal planes (transverse, sagittal, and coronal) with fluid-sensitive sequences with and without fat-suppression in at least two planes and thin slice thicknesses (≤2 mm), and were taken between 1 and 9 months after initial trauma.

Table 1. Demographics and characteristics of the study population ( n  = 10) .

Patient	Age (years)	Carpal malalignment	Radiolunate angle (deg)	Scapholunate angle (deg)	Initial injury	Initial treatment	MRI
1	28	VISI	32	36	Intra-articular distal radial fracture	Anterior plate fixation	No
2	37	VISI	42	34	Intra-articular distal radial fracture	Dorsal plate fixation	No
3	51	VISI	32	34	Intra-articular distal radial fracture; CRPS type II	Anterior plate fixation	No
4	53	DISI	–27	56	Posttraumatic CIND	Closed reduction and internal fixation with K-wires	Rupture of radiolunate ligament
5	59	DISI	–20	58	Posttraumatic CIND	Wrist arthroscopy and denervation	Rupture of radiolunate and radiotriquetral ligaments
6	28	VISI	51	35	Intra-articular distal radial fracture	Anterior plate fixation	No
7	38	VISI	25	39	Posttraumatic CIND; TFCC rupture	TFCC reconstruction with palmaris longus graft	Rupture of radiolunate ligament
8	33	VISI	33	31	Posttraumatic CIND	Conservative	Rupture of radiolunate, radioscaphocapitate, and radiotriquetral ligaments
9	29	VISI	23	31	Posttraumatic CIND; TFCC rupture	TFCC refixation	TFCC rupture
10	39	DISI	–27	30	Lunotriquetral ligament rupture	Fixation with K-wires	Rupture of radiolunate and radioscaphocapitate ligaments

Abbreviations: CIND, carpal instability nondissociative; CRPS, complex regional pain syndrome; DISI, dorsal intercalated segment instability; MRI, magnetic resonance imaging; TFCC, triangular fibrocartilage complex; VISI, volar intercalated segment instability.

The patients were contacted and asked to attend for reassessment. Subjective assessment was based on a Visual Analogue Scale (VAS) for pain (on a scale of 0–10 for severity); the Patient-Rated Wrist Evaluation (PRWE: 0 indicating no pain or functional problem, maximum 100); the Michigan Hand Questionnaire or MHQ, which results in a total score ranging from 0 to 100 with higher scores indicating better function; and the Disabilities of the Arm, Shoulder, and Hand—DASH—questionnaire. ^{9 10 11} The range of motion (ROM) of the wrist was determined using a goniometer and grip strength was measured with a Jamar dynamometer. Posteroanterior and lateral radiographs of the affected wrists were taken and assessed for osteoarthritic changes. In all but two patients (9 and 10), bilateral radiographs of the wrist were available.

Results

Details of the injuries and outcomes are summarized in Tables 1 and 2 . We were able to re-evaluate all patients except one, who passed away due to an unrelated cause. There were six male and four female patients with an average age of 41 years (range: 28–59 years). The mechanisms of injury included falls from a ladder or stairs, while inline skating, or riding a motorcycle, quad bike, or bicycle. The initial treatments varied and included treatment options such as open reduction of a distal radial fracture with plate fixation, closed reduction and internal fixation with K-wires, wrist arthroscopy and denervation, as well as triangular fibrocartilage complex (TFCC) refixation and reconstruction ( Table 1 ). All patients presented to our clinic with posttraumatic CIND-VISI or CIND-DISI between 1 day and 15 months after initial trauma. The injury was unilateral in all patients.

Table 2. Subjective and clinical outcomes at follow-up.

Patient	Follow-up after injury (months)	Follow-up after surgery (months)	Surgical treatment	Flexion (deg)	Extension (deg)	Grip strength (kg)	MHQ	PRWE	DASH	VAS	Osteoarthritis (X-ray)
1	22	N/A	No	70 (80)	60 (80)	40 (48)	80	20	25	2	Radiolunate
2	38	N/A	No	70 (80)	70 (80)	35 (52)	82	20	19	2	Radioscapholunate
3	14	N/A	No	75 (90)	25 (55)	20 (28)	76	11	19	1	Rradiolunate
4	84	78	Proximal row carpectomy	40 (80)	40 (65)	45 (50)	85	18	30	3	No
5	17	9	Proximal row carpectomy	40 (80)	40 (60)	46 (52)	73	16	16	0	No
6	29	16	Corrective osteotomy of distal radius; proximal row carpectomy	20 (70)	10 (60)	2 (34)	20	59	84	4	No
7	90	71	Radiolunate fusion	65 (65)	60 (60)	24 (32)	82	27	18	0	No
8	55	44	Radiolunate fusion	60 (90)	40 (70)	20 (34)	30	62	74	3	No
9	16 years and 10 months	12	Total wrist fusion	0 (65)	0 (60)	2 (50)	34	54	78	3	N/A
10	7 years and 11 months	82	Total wrist fusion	0 (70)	0 (80)	20 (54)	33	66	48	4	N/A

Abbreviations: DASH, Disabilities of the Arm, Shoulder, and Hand; MHQ, Michigan Hand Questionnaire; PRWE, Patient-Related Wrist Evaluation Score; VAS, Visual Analogue Scale.

Note: Values of the contralateral side are in brackets.

Conservative Treatment

After fixation of intra-articular distal radial fractures, three patients with posttraumatic CIND-VISI had no further treatment and at follow-up were satisfied with good subjective and clinical outcomes. In all the patients, wrist flexion/extension and grip strength were less than the contralateral healthy side ( Table 2 ).

Proximal Row Carpectomy

Two patients with posttraumatic CIND-DISI ( Fig. 1 ) and one patient with CIND-VISI after anterior plate fixation of intra-articular distal radial fractures were treated by proximal row carpectomy (PRC) via a dorsal approach because the CIND was irreducible. In these three cases, the long and short radiolunate ligaments were found to be loose at operation and were shortened with a few resorbable sutures (PDS 2.0/3.0) in the direction of the fiber. Patient number 6, who had CIND-VISI, underwent additional corrective distraction osteotomy of the distal radius via a volar approach and suffered from a complex regional pain syndrome, leading to a poor outcome. The other two were satisfied with good subjective and clinical outcomes, although wrist flexion/extension and grip strength were reduced when compared with the contralateral side.

Fig. 1.

Posteroanterior ( A ) and lateral ( B ) radiographs of the wrist of carpal instability nondissociative-dorsal intercalated segment instability (patient 5).

Radiolunate Fusion

Two patients of the reducible CIND-VISI group were treated with radiolunate fusion. Patient number 7 had an excellent subjective, clinical, and radiographic result, and was completely pain free 7.5 years after surgery ( Fig. 2 ). The other patient needed a revision procedure because of implant failure 6 weeks after initial surgery, which might explain a poorer result.

Fig. 2.

Posteroanterior and lateral radiographs of the wrist of carpal instability nondissociative-volar intercalated segment instability: preoperative ( A, B ) and postoperative after radiolunate fusion ( C, D ) (patient 8).

Total Wrist Fusion

The last two patients required total wrist fusion. Patient number 9 needed TFCC repair of a traumatic lesion to the TFCC. Due to severe radioulnar osteoarthritis with instability of the distal radioulnar joint (DRUJ) and CIND-VISI, an implantation of semiconstrained DRUJ prosthesis (Aptis Medical, Louisville, KY) and radiolunate fusion were performed 1.5 years later. Yet, the patient never felt pain free and underwent total wrist fusion. After this procedure, he still is not able to work and has mild wrist pain and very weak grip. Patient number 10 presented late after CIND-DISI with radiocarpal and midcarpal osteoarthritis. Total wrist fusion was the only available surgical option with moderate subjective and clinical results.

Radiological Results

Prior to treatment, radiological radiolunate angles were between 23 and 51 degrees in CIND-VISI and between –20 and –27 degrees in CIND-DISI. All patients had preserved scapholunate angles between 30 and 60 degrees demonstrating that the observed malalignment was not caused by intrinsic ligaments. Of the conservative group, all three patients with CIND-VISI developed asymptomatic radiolunate osteoarthritis ( Table 2 , Fig. 3 ).

Fig. 3.

Posteroanterior ( A ) and lateral ( B ) radiographs of the wrist of carpal instability nondissociative-volar intercalated segment instability with degenerative changes radiocarpal (patient 2).

On MRI, proximal ruptures of the radiolunate ligament were seen in all three patients with CIND-DISI ( Fig. 4 ). Differentiation of the long and short radiolunate ligaments was not possible. In addition, two of the three patients had bone marrow edema pattern in the distal radius at the insertion of the ligament ( Fig. 5 ). Only three patients with CIND-VISI had a usable MRI, one of which was completely unremarkable. The remaining two MRIs showed a proximal rupture of the radiolunate ligament. One had an additional rupture of the radioscaphoid-capitate ligament and the dorsal radiocarpal ligament. No rupture of the dorsal intercarpal ligament was seen on any of the MRI. The palmar ulnocarpal ligaments such as the ulnolunate and ulnotriquetral ligament could not be evaluated due to insufficient definition of the imaging.

Fig. 4.

Coronal proton-density-weighted magnetic resonance imaging sequence with fat-suppression of the wrist, demonstrating a complete rupture of the radiolunate ligament (arrow). The radioscaphocapitate ligament is intact (*, only partially displayed) (patient 4).

Fig. 5.

Magnetic resonance imaging of the wrist with coronal proton-density-weighted sequence with ( A ) fat-suppression and ( B ) sagittal T2-weighted sequence without fat-suppression. The radiolunate ligament is completely ruptured (arrows). There is associated bone marrow edema pattern in the distal radius (black arrowhead). No scapholunate dissociation is present (white arrowhead); the lunate bone demonstrates dorsal intercalated segment instability deformity (asterisk) (patient 10).

Discussion

All three conservative treated patients with posttraumatic CIND-VISI developed radiolunate osteoarthritis. Whether the osteoarthritis could have been prevented if a reduction of the proximal carpal row with ligament repair had taken place early on in these patients remains unclear. However, our patients are nearly pain free (VAS 1–2), PRWE between 11 and 20 and with good ROM of the wrist and grip strength. Fok et al ⁵ reported in three patients with reducible CIND-VISI following acute wrist fracture treated with open capsular repair who had a good ROM and none-to-mild pain.

Three patients with irreducible CIND (two with CIND-DISI, one with CIND-VISI) were treated by PRC and shortening of the long and short radiolunate ligaments, which is not a standard surgical procedure for CIND and not described in the literature. In cases in which posttraumatic CIND is irreducible, radiolunate fusion is not possible. We believe that PRC is a good option in this situation, especially in combination with shortening of the radiolunate ligament. Two patients showed satisfactory subjective (PRWE of 16 and 18) and clinical outcomes.

In previous reports, patients with CIND-DISI were usually treated nonsurgically, with palmar ligament reefing and/or dorsal intercarpal capsulodesis. ^{12 13} In all of these procedures the carpal bones must be reducible, which was not the case in our two patients.

Two patients with CIND-VISI were treated with radiolunate fusion to stabilize the entire proximal row in neutral. Despite reduction in grip strength, both patients were satisfied with the postoperative outcome. Postoperative ROM and outcome scores were excellent in one patient and still satisfactory in the second one. Halikis et al ¹⁴ reported excellent pain relief in five patients and Garcia-Elias ¹⁵ reported good preliminary results in a small series of nine patients with combined CIND. An alternative surgical option for CIND-VISI is midcarpal fusion, mostly triquetrohamate fusion and four-corner fusion. Goldfarb et al ¹⁶ reported that 7 of 8 patients were satisfied with 4-corner fusion and 6 of them had no pain or mild pain after surgery, compared with Rao and Culver, ¹⁷ who found only half of 10 patients had good or excellent result after triquetrohamate fusion. Shiga et al ¹⁸ analyzed palmar midcarpal instability and treatment by simulated triquetrohamate and radiolunate fusion in nine cadavers. They concluded, that both simulated partial wrist fusions stabilized the midcarpal joint.

Alternatively, in CIND-VISI without radiocarpal osteoarthritis and reducible carpal malalignment, a double-level tenodesis using a slip of the extensor carpi radialis brevis ¹⁵ or a stabilization of the triquetrohamate joint by rerouting the extensor carpi ulnaris tendon ¹⁹ or reefing of the dorsal radiotriquetral ligament ²⁰ can be used. Lichtman et al ²¹ compared the results of their midcarpal fusions with soft-tissue reconstruction and confirmed the advantage of midcarpal fusions.

On MRI we found no ruptures of the dorsal intercarpal ligament at high definition. However, whether the dorsal intercarpal ligament was underdeveloped or just showed increased laxity cannot be conclusively determined by the available MRI. We found only two ruptures of the radiotriquetral ligament, one patient with CIND-VISI, the other with CIND-DISI. All three patients with CIND-DISI had a proximal rupture of the radiolunate ligament. Louis et al ²² hypothesized that dorsal subluxation of the capitate occurs secondary to laxity of the radiolunate ligaments and the dorsal capitolunate complex. With our findings we can support this hypothesis. Fok et al ⁵ were unable to reproduce dorsal rotation of the proximal row consistent with CIND-DISI in cadaver dissections. Some authors consider wrist arthroscopy to be the gold standard for the evaluation of carpal instability. ²³ However, we have chosen diagnosis by MRI, a noninvasive imaging approach. Whether we would have seen more details by arthroscopy is unclear.

A major limitation to the study is that only 10 patients with wide heterogenicity could be included, but posttraumatic CIND represents an extremely rare medical condition. Only one other series of 12 patients with CIND after acute wrist fractures has been reported. ⁵

The data collected in this study may provide the first step toward better understanding of the pathology for this exceptionally rare finding. In CIND-VISI, we have not seen any ligament injury in four patients. Therefore, conservative therapy is more likely to be the first step. In CIND-DISI, we recommend an operative procedure: if detected early, with ligament suture, otherwise by radiolunate fusion, PRC, or total wrist fusion.

Funding Statement

Funding None.