Abstract
Background Perilunate dislocations are devastating injuries that occur relatively rarely, accounting for only 7% of injuries to the carpus. Unfortunately, approximately 25% of these injuries are missed on initial evaluation. Acutely diagnosed perilunate dislocations may be successfully treated with ligament and osseous repair, depending on the injury pattern. Chronic dislocations, however, are primarily treated with salvage procedures. This case series was performed to investigate the outcomes of patients who sustained a perilunate dislocation that was diagnosed in a delayed fashion and look for any treatment patterns that could be more widely applied to future patients.
Methods Patients presenting to a single institution between 2016 and 2018 with a perilunate injury that either presented in a delayed fashion or was missed on initial assessment were identified and their characteristics were evaluated. The surgical management of these patients was assessed as was their postoperative course at their 2-week, 6-week, 3-month, and 6-month clinic follow-up visits.
Results Eight patients were identified with perilunate dislocations that were diagnosed in a delayed fashion. On average, these dislocations were diagnosed 133 days following the date of injury. All patients were males and 7/8 of them were between 17 and 20 years of age at the time of their injury (mean age: 25.5). They were treated with either primary repair, wrist fusion, proximal row carpectomy, or scaphoid excision and four-corner fusion (SEFCF). Both pain and range of motion improved following surgical management of these injuries.
Conclusion Perilunate dislocations are rare injuries that are notorious for being diagnosed late, at which point primary repair is oftentimes no longer feasible. Salvage procedures are able to improve the range of motion and pain of patients who are found to have chronic dislocations. Our case series highlights the importance of treating each missed perilunate injury individually and avoiding a “one-size-fits-all” approach.
Keywords: perilunate dislocations, missed perilunate dislocations, wrist trauma, lunate, perilunate
Perilunate dislocations are serious injuries that occur relatively rarely, accounting for only 7% of injuries to the carpus. They typically result from high-energy mechanisms and are frequently associated with acute carpal tunnel syndrome. 1 Unfortunately, approximately 25% of these injuries are missed on initial evaluation. 2 These missed injuries can cause devastating alterations in people's function due to pain, stiffness, and nerve deficits.
Acutely diagnosed perilunate are typically treated with ligament and osseous repair, depending on the injury pattern. Chronic dislocations, however, are primarily treated with salvage procedures, including arthrodesis and/or excision of carpal bones.
This case series aimed to investigate the outcomes of patients who sustained a perilunate dislocation that was diagnosed in a delayed fashion and to identify patient characteristics associated with missed diagnosis. We also identified potential treatment options depending on the patient's injury characteristics, with the goal of discovering potential treatment algorithms for these injuries.
Methods
Patients presenting to a single institution between 2016 and 2020 with a perilunate injury that either presented in a delayed fashion or was missed on initial assessment were identified and their characteristics were evaluated. Information collected included basic demographics, time to diagnosis, injury characteristics, type of interventions performed, postoperative pain scores, and wrist range of motion. Patients were divided into subacute and chronic groups for discussion purposes. Subacute was defined as presenting less than 30 days from time of injury.
The study was submitted to our local institutional review board and was designated exempt status.
Descriptive statistics were run on the data set. Sample size was too small to perform comparisons between subgroups.
Results
Eight patients were identified with perilunate dislocations that were diagnosed in a delayed fashion ( Tables 1 and 2 ). On average, these dislocations were diagnosed 133 days (range: 3–273) following the date of injury. All patients were males and 87.5% (7/8) of them were between 17 and 20 years of age at the time of their injury (mean age: 25.5). Half of the injuries were greater arc injuries. 75% (6/8) were classified as Mayfield stage 3, one was stage 2, and one was stage 4. Three patients were treated with proximal row carpectomy (PRC), three were treated with primary repair (including scaphoid open reduction internal fixation (ORIF), carpal pinning, and lunotriquetral ligament repair), one was treated with scaphoid excision and four-corner fusion (SEFCF), and one was treated with wrist arthrodesis. Prophylactic carpal tunnel release (CTR) was performed in 62.5% (5/6) of patients ( Tables 3 and 4 ).
Table 1. Chronic Injuries.
| Clinical vignette | Injury films | Postoperative films |
|---|---|---|
| C1: 43M who presented 199 d after injury found to have a Mayfield stage 2 injury with associated radiocarpal fracture dislocation treated with a PRC and interpositional grafting |
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| C2: 19M who presenting 273 d after injury with a Mayfield stage 4 transscaphoid injury treated with PRC, temporary pinning of the radiocarpal joint, and prophylactic CTR |
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| C3: 18M presenting 123 d after injury with Mayfield stage 3 injury treated with scaphoid excision and four-corner fusion |
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| C4: 18M presenting 120 d after injury with Mayfield stage 3 injury treated with wrist arthrodesis and prophylactic CTR |
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| C5: 16M presenting 228 d after injury with Mayfield stage 3 injury treated with PRC |
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Table 2. Subacute injuries.
| Clinical vignette | Injury films | Postoperative films |
|---|---|---|
| 20M presenting 5 d after injury with Mayfield stage 3 transscaphoid injury treated with scaphoid ORIF, LT repair, and prophylactic CTR |
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| 22M presenting 6 d after injury with Mayfield stage 3 transscaphoid injury treated with scaphoid ORIF, pinning, and prophylactic CTR |
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| 20M presenting 3 d after injury with Mayfield stage 3 injury and acute carpal tunnel syndrome treated with SL ligament repair and CTR |
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Table 3. Mayfield perilunate injury classification system.
| Stage 1 | Scaphlounate (SL) dissociation |
| Stage 2 | Addition of lunocapitate dissociation |
| Stage 3 | Addition of lunotriquetral (LT) dissociation |
| Stage 4 | Addition of lunocarpal dissociation |
Table 4. Demographic and injury characteristics.
| Chronic cohort | |||||||
| ID | Sex | Arc classification | Mayfield stage | Age | Time to diagnosis (d) | Management | Prophylactic CTR |
| C1 | M | Greater | 2 | 43 | 199 | PRC | No |
| C2 | M | Greater | 4 | 19 | 273 | PRC | Yes |
| C3 | M | Lesser | 3 | 18 | 123 | SEFCF | No |
| C4 | M | Lesser | 3 | 18 | 120 | Arthrodesis | Yes |
| C5 | M | Lesser | 3 | 16 | 228 | PRC | No |
| Mean | 22.8 | 187 | |||||
| Subacute cohort | |||||||
| ID | Sex | Arc classification | Mayfield stage | Age | Time to diagnosis (d) | Management | Prophylactic CTR |
| S1 | M | Greater | 3 | 20 | 5 | Scaphoid ORIF, LT repair | Yes |
| S2 | M | Greater | 3 | 22 | 6 | Scaphoid ORIF, pinning | Yes |
| S3 | M | Lesser | 3 | 20 | 3 | Repair | Yes |
| Mean | 20.6 | 4.67 | |||||
Postoperative wrist range of motion is reported in Table 5 . Mean flexion was 43.3 degrees (range: 0–80). Mean extension was 46.6 degrees (range: 0–70). Mean postoperative pain was 2.25 on a 10-point scale (range: 0–8, Table 6 ). Mean time to postoperative follow-up was 140 days (range: 27–314).
Table 5. Postoperative wrist range of motion.
| Flexion (degrees) | Extension (degrees) | |
|---|---|---|
| C1 | 30 | 30 |
| C2 | a | a |
| C3 | 80 | 50 |
| C4 | NA | NA |
| C5 | 50 | 70 |
| Mean | 53.3 | 50 |
| S1 | 30 | 30 |
| S2 | 30 | 60 |
| S3 | 40 | 40 |
| Mean | 33.3 | 43.3 |
Abbreviation: NA, not available.
Data not collected at follow-up visit.
Table 6. Postoperative pain scores (visual analog scale).
| Pain | No. of days postoperative at evaluation | |
|---|---|---|
| C1 | 8 | 167 |
| C2 | 4 | 27 |
| C3 | 0 | 232 |
| C4 | 6 | 86 |
| C5 | 0 | 103 |
| Mean | 3.6 | 123 |
| S1 | 0 | 92 |
| S2 | 0 | 314 |
| S3 | 0 | 99 |
| Mean | 0 | 168 |
Discussion
Here we report on eight cases of missed perilunate dislocations. In general, perilunate injuries are the result of high-energy forces and result in permanently altered wrist function, even when diagnosed and treated promptly. Most of these injuries occurring in young people, which is consistent with the demographics of our cohort.
Overall, the reported postoperative pain was acceptable in this cohort. All but two patients reported pain levels less than 5 and all of the patients in the subacute group reported no pain at follow-up. There are two possible explanations for this. First, that prompt treatment leads to better outcomes in perilunate dislocations. Previous published data demonstrate similar clinical outcomes between perilunate injuries treated acutely and those treated up to 45 days from injury. 2 Second, that the type of intervention influences patient-reported outcomes since all of our subacute patients were treated with primary fixation and/or repair. While it is most likely a combination of both these factors, we are unable to elucidate the extent to which either time to diagnosis or type of intervention predicts postoperative pain due to our small sample size.
The mean wrist flexion and extension reported in our cohort was well within functional ranges of motion (excluding the patient treated with wrist fusion and the patient we did not have range of motion data on). Previous biomechanical studies have reported that most typical daily tasks can be performed with an arc of 5 to 30 degrees. 3 4 This indicates that treatment of chronic perilunate dislocations, even with “salvage” procedures like proximal row carpectomies and fusions, provide adequate functional outcomes for young patients.
Various options for treatment of missed perilunate dislocations have been described in the literature (including arthroscopic reduction and fixation, capitate prosthesis, proximal row carpectomy, and open reduction internal fixation) without a clear consensus on preferred intervention. 5 6 7 8 9 This lack of consensus is also reflected in our cohort, with a total of five different procedures being performed for eight patients. All patients who presented subacutely were treated with primary repair and prophylactic carpal tunnel release. Patients presenting with chronic injuries were treated with a variety of surgical interventions including proximal row carpectomies and fusions with or without carpal tunnel release (independent of Mayfield stage). Primary repair is not an option for patients with significantly delayed presentation due to the presence of intercarpal and radiocarpal joint degeneration. A similar explanation can be offered in regard to prophylactic carpal tunnel releases. After a certain amount of time, any deficits from acute carpal tunnel syndrome are unlikely to be recovered by decompressing the nerve. A preoperative electromyography (EMG) may be helpful in determining the reversibility of median neuropathy symptoms, but only if it does not delay treatment.
In summary, missed perilunate dislocations overwhelmingly affect young men. While subacute injuries can be treated similarly to acute injuries with good results, chronic perilunate injuries must be approached individually. Individualized treatment of chronic injuries is crucial because there is not one intervention that will successfully treat all chronic injury patterns. This case series highlights the importance of early identification of perilunate injuries and the necessity of individualized surgical treatment plans when these injuries are missed.
Footnotes
Conflict of Interest None declared.
References
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