Patient Satisfaction with Pisiform Excision for Pisotriquetral Instability or Arthritis: A Prospective Review

Abstract

Background  Pisotriquetral pain and instability is an elusive cause of ulnar-sided wrist pain. Initial treatment of chronic pisotriquetral pathology should involve a trial of nonoperative therapy such as neutral wrist splint, anti-inflammatories, and intra-articular steroid injections. The mainstay of surgical management of pisotriquetral pain is pisiform excision.

Purpose  This prospective study seeks to understand patient satisfaction after pisiform excision in patients with isolated pisotriquetral pathology.

Patients and Methods  A consecutive series of nine cases of pisiform excision was performed by the senior surgeon. The primary outcome measure was determined a priori to be the Patient-Rated Wrist Evaluation (PRWE) score. Wrist range of motion, grip strength, and QuickDASH (shortened version of Disabilities of the Arm, Shoulder and Hand) scores were also collected preoperatively and at 3 and 12 months postoperatively as secondary outcome measures.

Results  There was a very rapid improvement in the PRWE by 3 months, which was maintained at 12 months. The QuickDASH score was slower to improve, with a significant improvement by 12 months. There was no change in grip strength or wrist range of motion at any time point.

Conclusion  Pisiform excision results in a very rapid improvement of symptoms and should be considered in cases of pisotriquetral instability or arthritis that fail conservative management.

Level of Evidence  Level IV, case series.

The pisiform is the smallest carpal bone and is located palmar to the three bones of the proximal carpal row. A sesamoid bone that is nearly spherical in shape, it is embedded within the flexor carpi ulnaris (FCU) tendon. Its only articulation is with the triquetrum. The pisiform's blood supply is via its proximal and distal poles by branches of the ulnar artery. The pisiform acts as the ulnar wall to Guyon's canal. ¹ It is supported by many soft-tissue attachments including the FCU tendon, the transverse carpal ligament (TCL), the abductor digiti minimi, the extensor retinaculum, the pisometacarpal ligament, the pisohamate ligament, the anterior carpal ligament, and the pisotriquetral (PT) joint capsule. ²

The pisiform ligament complex has primary and secondary stabilizers to the PT joint. The primary stabilizers are the pisohamate, pisometacarpal, and ulnar PT ligaments. The TCL and radial PT ligaments are secondary stabilizers. Injuries of the primary stabilizers of the PT joint may lead to instability that predisposes to pain and degenerative joint disease. ^{3 4}

The pisiform functions as a fulcrum to enhance the pull of the FCU muscle similar to other sesamoid bones such as the patella. ³ Approximately half of the FCU tendon attaches to the pisiform and the rest is a bundle of fibers functioning as a roof over the pisiform as these fibers continues distally. ⁵ Paley and colleagues found that FCU tendinopathy accounts for up to 44% of palmar ulnar-sided wrist pain cases. ⁶ This tendinopathy is highly correlated with PT joint instability and arthrosis. ⁷ The treating physician should have a high index of suspicion for associated PT pathology when diagnosing a patient with FCU tendinopathy. ¹

The clinical evaluation of PT arthritis reveals tenderness about the pisiform and often the adjacent soft tissues. Crepitus and mechanical symptoms may exist about the pisiform with wrist motion. The pisiform shuck test is a provocative maneuver that is performed by manually displacing the pisiform radially and ulnarly, causing grinding against the triquetrum. A positive test produces pain and crepitus; pain alone can indicate PT instability. If there is diagnostic uncertainty, the authors prefer to perform a diagnostic injection of local anesthetic and corticosteroid into the PT joint. Full resolution of pain with infiltration of local anesthetic confirms PT arthritis.

Radiographs can also be useful to evaluate the PT joint, although the authors find that in our hands a computed tomography (CT) scan is a more reliable diagnostic tool. Jameson and colleagues described an optimal series of four views for evaluating the PT joint and PT motion: wrist neutral with 30-degree forearm supination, wrist extension with 30-degree forearm supination, active wrist flexion and thumb abduction with 45-degree forearm supination, and passive wrist flexion and thumb abduction with 45-degree forearm supination. ⁸ CT of the wrist shows joint space narrowing, osteophytes, subchondral sclerosis, and/or subchondral cysts at the PT joint ( Fig. 1 ).

Fig. 1.

Axial and lateral cuts of a CT scan of the wrist illustrating decreased joint space, osteophytes, and subchondral sclerosis of the pisotriquetral joint. Subchondral cysts may also be present.

Initial treatment of chronic PT pathology should involve a trial of nonoperative therapy such as neutral wrist splint, anti-inflammatories, and intra-articular steroid injections. ³ The mainstay of surgical management of PT pain is pisiform excision; however, PT arthrodesis has also been described. ⁹ Pisiform excision has been described as good solution for patients who fail conservative treatment as it decreases pain without limiting the range of motion (ROM). ^{10 11 12 13 14 15 16 17} However, these studies were retrospective and analyzed small series of patients with a heterogenous patient cohort and few patient-reported outcomes. To our knowledge, there is only one other study in the literature that includes prospectively collected data. van Burink and colleagues included 175 patients who underwent pisiform excision; however, there was significant concomitant diagnoses including FCU tendinitis, ulnar neuropathy, and “other.” ¹⁸ We are not aware of any prospective studies that examine outcomes in pisiform excision in the context of isolated PT arthritis. The purpose of this study is to describe the improvement in patient-rated outcome measures (PROMs), ROM, and grip strength in a prospective manner from the collected cohort of patients who failed conservative management and were treated with pisiform excision.

Patients and Methods

Between 2015 and 2021, a consecutive prospective series of nine cases of pisiform excision were performed by the senior surgeon on nine patients (average age: 62.3 ± 3.1 years). Six of these patients had left-sided procedures and three had right-sided procedures. All nine patients were right-hand dominant. Eight patients had osteoarthritis of the PT joint on CT; the ninth patient did not have PT osteoarthritis but had symptoms of pisiform instability. Data were obtained from a wrist pain database that prospectively tracks patients presenting to our clinic with chronic wrist pain since 2015. Only patients failing conservative treatment and electing surgical management due to chronic PT pathology were selected from the database. We excluded 14 patients because they did not meet our inclusion criteria (11 participants opted for conservative treatment, 2 participants had prior ipsilateral surgical treatment in the hand) or were lost to follow-up (1 participant).

Informed consent and approval by our institutional ethics review board were obtained for each patient. Patient-reported outcome measures were prospectively collected preoperatively and at 3 and 12 months postoperatively. The primary outcome measure was determined a priori to be the Patient-Rated Wrist Evaluation (PRWE), as it is the most disease-specific patient-reported outcome measure available. The PRWE is a 15-item questionnaire designed to measure wrist pain and disability in activities of daily living. It was developed and subsequently validated as a responsive instrument to measure patient-perceived outcome for wrist disorders. ¹⁹ The secondary outcomes were wrist ROM, grip strength, and QuickDASH (shortened version of Disabilities of the Arm, Shoulder and Hand) scores. The QuickDASH score is a validated scale used to assess patient functional status with upper extremity conditions. ^{20 21} The minimal clinically important difference (MCID) of the PRWE and QuickDASH has been reported in the literature to be 14 for each respective tool; therefore, we predetermined that we would use these values for our analysis. ²²

The patients were clinically evaluated preoperatively by the senior surgeon. CT scans were performed on all patients. The physical examination included wrist ROM, measurement of affected and contralateral wrist, grip strength, and comprehensive, standardized wrist examination. Wrist flexion, extension, and radial and ulnar deviation were measured with a standard goniometer and recorded at 0, 3, and 12 months postoperatively. Grip strength was measured using a Jamar dynamometer. Standardized wrist examination was used to rule out any alternate sources of ulnar-sided wrist pain and confirm the diagnosis. We specifically excluded any symptoms of ulnar neuropathy, ulnar impaction syndrome, or median neuropathy.

Surgical Technique

As described by Rayan, ³ a volar Bruner incision was marked over the ulnar aspect of the palm over the course of the FCU and extended proximally to identify the ulnar nerve. Guyon's canal was only released enough to identify and protect the ulnar nerve ( Fig. 2 ). The FCU tendon was identified proximally as was the ulnar nerve ( Fig. 3 ). The nerve was meticulously protected for the remainder of the procedure. The pisiform was excised through a longitudinal split of the FCU tendon anteriorly ( Fig. 4 ). Careful dissection staying on the pisiform preserves the FCU tendon and any distal and ulnar insertions of the FCU. The pisiform was excised with preservation of the surrounding soft-tissue confluence. The FCU tendon was repaired. The wound was closed. Bulky dressings and splint were applied with the wrist in neutral to slight flexion for 2 weeks. After 2 weeks, the plaster splint was removed, wounds were inspected, and the patient was provided with a removable wrist splint to be weaned as their symptoms allow. The patient was instructed to begin physiotherapy exercises at this time to regain strength and ROM.

Fig. 2.

Our typical Bruner incision for excision of the pisiform. Care must be taken to identify and protect the ulnar nerve.

Fig. 3.

Cadaveric dissection illustrating the course of the ulnar nerve relative to the FCU tendon and pisiform. Note that it is not necessary to dissect the nerve out proximally. a, ulnar artery; n, ulnar nerve; p, pisiform within the flexor carpi ulnaris tendon.

Fig. 4.

The FCU tendon is split longitudinally to isolate and excise the pisiform. a, ulnar artery; n, ulnar nerve; p, pisiform within the flexor carpi ulnaris tendon.

Statistical Analysis

The data were analyzed using IBM SPSS (IBM Corp. Released 2020. IBM SPSS Statistics for Windows, Version 27.0. Armonk, NY: IBM Corp). Descriptive analysis and a paired t -test were conducted with an alpha value set at 0.05.

Results

Nine participants were included in the study. Patient characteristics are summarized in Table 1 . The mean age of patients was 62.3 (±6.7) years. Eight patients were female, and one patient was male. All patients were right-handed; four had left-sided surgery and five had right-sided surgery. Intraoperative osteoarthritis of the PT articulation was documented in six patients.

Table 1. Patient characteristics.

Age, y	Gender	Side	Handedness	CT findings	Operative findings
58	Female	Left	Right	Osteoarthritis	Osteoarthritis
55	Male	Left	Right	Osteoarthritis	Chondromalacia
55	Female	Left	Right	Osteoarthritis	Osteoarthritis
59	Female	Right	Right	Osteoarthritis	Not documented
72	Female	Right	Right	Osteoarthritis	Osteoarthritis
56	Female	Left	Right	Osteoarthritis	Osteoarthritis
73	Female	Right	Right	Osteoarthritis	Osteoarthritis
58	Female	Right	Right	Osteoarthritis	Osteoarthritis
56	Female	Right	Right	No osteoarthritis	No gross abnormality

Abbreviation: CT, computed tomography.

The PRWE showed a rapid improvement in symptoms. By 3 months, the mean PRWE score had improved by 25.9 ± 17.9 points ( p  = 0.005), on a scale of 0 to 100. The MCID for isolated tendonitis, arthritis, or nerve compression symptoms has been reported to be 14. ²² Therefore, patients had a statistically and clinically significant improvement at 3 months, which was maintained at their 12-month visit. This finding held for the total PRWE as well as the pain and function subscores, as outlined in Table 2 . There was not a statistically significant improvement from the 3- to 12-month follow-ups, which highlights the fact that the greatest improvement occurred in the first 3 months postoperatively.

Table 2. Patient-reported outcome measures.

Measure (range)	Baseline	3 mo	12 mo
PRWE pain (0–50)	25.0 (±12.5)	12.0 (±10.7)**	8.4 (±7.1)*
PRWE function (0–50)	22.1 (±14.3)	9.1 (±12.8)*	4.3 (±6.1)*
PRWE total (0–100)	47.1 (±24.3)	21.1 (±22.9)**	12.7 (±12.1)**
QuickDASH (0–100)	40.9 (±23.7)	27.3 (±23.8)	12.0 (±12.4)*

Abbreviations: PRWE, Patient-Rated Wrist Evaluation; QuickDASH, shortened version of Disabilities of the Arm, Shoulder and Hand.

* p  < 0.05 compared to baseline. ** p  < 0.01 compared to baseline.

We also administered the QuickDASH questionnaire, which is a more general patient-reported outcome measure used to evaluate the functional status of the entire upper extremity. Although there was a trend toward improvement at 3 months, this did not become statistically significant until 12 months. The MCID for the QuickDASH for isolated tendonitis, arthritis, or nerve compression symptoms has been reported to be 14. ²² By 3 months postoperatively, patients had improved by a mean of 13.6 ± 18 points ( p  = 0.093), suggesting a trend toward clinical significance. At their 12-month visit, patients had improved by a mean of 22.7 ± 17.1 points ( p  = 0.013), which was both clinically and statistically significant.

At baseline, there was no significant difference in wrist extension, flexion, pronation, supination, radial deviation, or ulnar deviation between the affected and contralateral wrist. There was no significant change in the ROM of the affected wrist between baseline, 3-month follow-up, and 12-month follow-up ( Table 3 ). The affected grip strength was on average 5.6 ± 7.1 kg less than the contralateral side at baseline ( p  = 0.033). This is less than the reported MCID of 6.5 kg; therefore, this is unlikely of clinical significance. ²³ There was no significant change in the grip strength of the affected wrist between baseline, 3-month follow-up, and 12-month follow-up.

Table 3. Physical exam of affected limb.

	Baseline	3 mo	12 mo
Supination (degree)	82.5 (±7.2)	83.6 (±5.6)	83.4 (±9.4)
Pronation (degree)	71.3 (±14.7)	65.5 (±12.2)	72.3 (±6.4)
Wrist flexion (degree)	66.1 (±16.1)	62.3 (±16.0)	76.0 (±12.3)
Wrist extension (degree)	57.3 (±12.5)	50.3 (±7.6)	47.5 (±11.9)
Radial deviation (degree)	24.1 (±10.2)	18.0 (±4.8)	21.2 (±7.3)
Ulnar deviation (degree)	28.0 (±7.8)	29.0 (±7.5)	28.2 (±6.8)
Grip strength (kg)	19.6 (±10.8)	16.2 (±7.0)	20.5 (±6.4)*

* p  < 0.05 compared to 3 months.

Discussion

Excision of the pisiform is the most widely accepted treatment for pisiform arthritis or instability refractive to nonoperative management. Retrospective studies have shown good patient satisfaction that is maintained over long-term follow-up. ^{10 12 24} In one of the earliest large retrospective case series, Carroll and Coyle described complete relief in 65 of 76 wrists treated with pisiform excision with no loss of strength and no late problems associated with the FCU function. ²⁵ Many patients had coincident diagnoses such as ulnar nerve symptoms (22/66) and median nerve symptoms (7/66), pisiform nonunion (3/66), and ulnar impaction syndrome treated previously with ulnar shortening osteotomy (4/66). Pathology showed abnormality in the PT joint of the majority of cases, but 7/76 specimens had a pathologically normal pisiform. Other intraoperative findings included calcium deposits in the FCU (3/76), focal necrosis of the FCU insertion into the pisiform (2/76), Dupuytren's contractures (2/76), and a cavernous hemangioma (1/76). No standardized outcomes measures were used. ²⁵

We have described outcomes of nine cases of pisiform excision for painful PT joint. The patients were recruited prospectively into a database, and preoperative and postoperative subjective and objective evaluations were completed. The patients improved dramatically from their preoperative assessment in terms of PRWE and QuickDASH. This improvement occurred rapidly by the 3-month postoperative visit and was maintained at 1 year. Unlike previously published literature, our cohort excluded patients with concomitant diagnoses around the PT joint. We used a combination of CT imaging confirming arthritic change of the PT joint and confirmation with temporary relief with injection of anesthetic into the PT joint to confirm the primary diagnosis of PT arthritis. Other studies have included patient with multiple overlapping diagnoses including FCU calcific tendonitis, ulnar nerve compression, triangular fibrocartilage complex injuries, distal radioulnar joint pathology, and inflammatory arthropathy. ^{13 16 18 24 25} These confounding pathologies would be expected to interfere with outcomes assessment of pisiform excision for PT pathology. We found that the pisiform was grossly arthritic at the time of surgery in six of nine patients. One patient had chondromalacia confirmed by pathologic examination, one patient had no gross degeneration but was not sent to pathology, and the state of the final pisiform was not documented. The positive response to surgery suggests that good outcome can be expected in isolated pisiform excision, even if the joint is not grossly arthritic. This is consistent with prior literature describing painful pisiform instability with good results from surgical excision of the pisiform. ^{3 26 27}

Validated PROMs have been previously used in the literature to evaluate the results of pisiform excision. ^{13 17 24} De Almeida and colleagues used the QuickDASH and PRWE to evaluate long-term follow-up of 12 wrists treated with pisiform excision for PT arthritis. ¹³ QuickDASH and PRWE improved significantly at the final review visit in their retrospective study. They additionally collected visual analogue scale (VAS) scores, ROM, grip strength, and clinical evaluation for ulnar neuritis, which was present in 3/12 patients. At final review (mean: 7.5 years), there was a trend toward decreased grip strength in the operative hand, which was not statistically significant, and the only statistically significant difference was a slight decrease in extension range compared with the contralateral side. ¹³

Verhiel et al retrospectively reviewed 37 patients with pisiform excision at median follow-up of 10 years. ²⁴ Sixteen patients were noted to have ulnar nerve compression preoperatively, which resolved completely in 10/16. The outcome measures were QuickDASH, VAS, satisfaction, complications, and reoperation rate. They found low QuickDASH scores at final follow-up (median score: 4.5) and high satisfaction (median score: 10), although they did not collect preoperative QuickDASH scores. The complication rate was 13% and included ulnar nerve symptoms, local infection, and suture granuloma. There were no reoperations. They recommended the procedure for refractory pisiform pain or FCU enthesopathy. ²⁴

We measured grip strength in our series and found that there was a trend toward transient loss of grip strength at 3 months postoperatively, which was not statistically significant, and grip strength returned to baseline by the 12-month follow-up. Lam and colleagues also found that there was no significant difference in grip strength or ROM after pisiform excision. ¹⁵

O'Keefe et al analyzed FCU forces in the dart-throwing motions in the cadaveric model and found that pisiform excision resulted in greater forces required for two types of dart-throwing motion. ⁹ There was no difference between FCU forces in intact wrists and those with pisiform arthrodesis for either type of dart-throwing motion in their model. There have been case reports of PT arthrodesis carried out in high performance athletes such as gymnasts and mountain bikers where fear of loss of protection of the ulnar nerve and loss of wrist flexion power might adversely affect performance in sport. ^{28 29} However, Rayan and colleagues measured isometric and isokinetic forces in patients after pisiform excision and found that mean isometric wrist flexion force was 94% of the opposite hand and mean isokinetic flexion strength was 113%. ⁴ The mean isometric ulnar deviation strength was 87% and the mean isokinetic ulnar deviation strength was 103%. They emphasized the importance of surgical technique that did not violate the stabilizing ligaments of the PT joint. Lam and colleagues similarly found no significant difference in static or dynamic wrist strength in wrist flexion and extension and dynamic power. ¹⁵

There are several limitations to our study. This is a small case series of only nine patients, and follow-up was limited to 1 year. Larger prospective series are needed to confirm our findings. We did not send our specimens for pathological confirmation, which may be helpful in future studies to determine if pisiforms lacking gross arthritis still benefit from excision.

Conclusion

Pisiform excision is an excellent procedure for patients with PT degeneration refractory to conservative management. Improvement occurs quickly, with substantial improvement in the PRWE by 3 months postoperatively. Pisiform excision had no temporary or longer term effect on wrist flexion, extension, pronation, supination, radial deviation, ulnar deviation, or grip strength.