The AO Ulnar Shortening Osteotomy System Indications and Surgical Technique

Algorithm-Guided Treatment of Ulna Impaction Syndrome: A 10-Year Follow-Up Study of Ulna Shortening Osteotomy and Wafer Procedure

Background: Ulnar impaction syndrome (UIS) is a common degenerative wrist condition which results from positive ulnar variance, leading to an overload on the ulnar carpus. Ulnar shortening osteotomy (USO) and the arthroscopic wafer procedure (AWP) are established therapies for UIS if conservative management fails. This study assessed an algorithm-guided treatment of UIS over a period of 10 years. Methods: This prospective observational study compared the outcome of 54 patients who underwent either USO or AWP for UIS based on a predefined treatment algorithm. The mean follow-up period was 10 years. Primary outcome parameters were the visual analogue scale (VAS) for pain and the Disabilities of the Arm, Shoulder, and Hand questionnaire (DASH), whereas secondary outcome parameters were grip and pinch strength and range of motion. Results: The median preoperative ulnar variance was 2.6 mm in the USO group and 2.0 mm in the AWP group. The postoperative average ulnar variance was 0 mm in both groups. The preoperative pain at rest was 3.4 in the USO group and 2.3 in the AWP group. One year after surgery, there was a significant reduction to VAS 0.7 and 0.2, respectively. These results persisted to the 10-year follow-up (VAS 0.9 and 0.2). The pain in motion also decreased significantly in the first year (from 6.8 and 6.7 to 2.2 and 2.1), as well as after 10 years (2.4 and 1.0). The preoperative DASH score averaged 31.3 in the USO group and 35.8 in the AWP group. At the 10-year follow-up, the DASH of both groups decreased significantly to 4.35 in the AWP group compared to 12.7 in the USO group. Conclusions: Our data show that, when using our algorithm, both USO and AWP, two common operative treatment options of UIS, reliably reduce pain and significantly reduce the DASH score over at least a period of ten years. The results after 10 years differ from short-term results in so far as after one year, the USO group showed to some degree similar outcome parameters compared to AWP, whereas at the 10-year follow-up, AWP reached slightly better primary outcome parameters. The algorithm presented, thus, produced excellent short- and long-term outcomes. Our findings and the applied algorithm can assist in decision-making and patient education.

Enabling the design of surgical instruments for under-resourced patients through metal additive manufacturing: ulnar shortening osteotomy as an example

BACKGROUND

Ulnar shortening osteotomy (USO) has demonstrated good outcomes for patients with ulnar impaction syndrome. To minimize complications such as non-union, precise osteotomy and firm fixation are warranted. Despite various ulnar shortening systems have been developed, current technology does not meet all needs. A considerable portion of patients could not afford those designated USO systems. To tackle this challenge, our team reported successful results in standardized free-hand predrilled USO technique. However, it is still technical demanding and requires sufficient experience and confidence to excel. Therefore, our team designed an ulnar shortening system based on our free-hand technique principle, using metal additive manufacturing technology. The goal of this study is to describe the development process and report the performance of the system.

METHODS

Utilizing metal additive manufacturing technology, our team developed an ulnar shortening system that requires minimal exposure, facilitates precise cutting, and allows for the easy placement of a 3.5 mm dynamic compression plate, available to patients at zero out-of-pocket cost. For performance testing, two surgeons with different levels of experience in ulnar shortening procedures were included: one fellow-trained hand and wrist surgeon and one senior resident. They performed ulnar shortening osteotomy (USO) using both the free-hand technique and the USO system-assisted technique on ulna sawbones, repeating each method three times. The recorded parameters included time-to-complete-osteotomy, total procedure time, chip diameter, shortening length, maximum residual gap, and deviation angle.

RESULTS

For the hand and wrist fellow, with the USO system, the time-to-complete osteotomy was significantly reduced. (468.7 ± 63.6 to 260.0 ± 5 s, p < 0.05). Despite the preop goal was shortening 3 mm, the average shortening length was significantly larger in the free-hand group (5 ± 0.1; 3.2 ± 0.2 mm, p < 0.05). Both maximum residual gap and deviation angle reported no statistical difference between the two techniques for the hand surgeon. As for the senior resident, the maximum residual gap was significantly reduced, using the USO system (2.9 ± 0.8; 0.4 ± 0.4 mm, p = 0.02). Between two surgeons, significant larger maximum residual gap and deviation angle were noted on the senior resident doctor, in the free-hand technique group, but not in the USO system group.

CONCLUSION

The developed USO system may serve as a valuable tool, aiding in reliable and precise cutting as well as fixation for patients undergoing ulnar shortening osteotomy with a 3.5 mm dynamic compression plate, even for less experienced surgeons. The entire process, from concept generation and sketching to creating the CAD file and final production, serves as a translatable reference for other surgical scenarios.

Sliding Plate System: A Novel Method and Device for Shortening Osteotomy

We report a novel sliding plate system (SPS) and its application for radial shortening osteotomy. We conceptualised, designed and introduced the SPS, which helps with precise shortening osteotomy in both radius and ulna. We implanted the SPS in a patient with Kienböck disease following a radius shortening osteotomy. The SPS was safe and efficient, and the surgical technique eliminated extra steps. The SPS affords precise shortening, optimum compression and anatomic alignment after radius shortening osteotomy. Level of Evidence: Level V (Therapeutic).

Is ulnar shortening osteotomy or the wafer procedure better for ulnar impaction syndrome?: A systematic review and meta-analysis

BACKGROUND

Wrist pain on the ulnar side is often caused by ulnar impaction syndrome (UIS). Idiopathic UIS requires surgical treatment when conservative treatment fails. The 2 main surgical procedures used are the wafer procedure and ulnar shortening osteotomy (USO) of the metaphysis or diaphysis. This review aimed to analyze comparative studies of the 2 procedures in UIS to determine clinical outcomes and complications.

METHODS

One prospective and 5 retrospective comparison trials were retrieved from the PubMed, Embase, and Cochrane Library databases. The primary outcomes were treatment effectiveness; pain visual analog scale (VAS), disabilities of the arm, shoulder, and hand (DASH) score, Mayo wrist, and Darrow scores. The incidence of postoperative complications formed the secondary outcome.

RESULTS

The selected studies included 107 patients who underwent the wafer procedure (G1) and 117 patients who underwent USO (G2). The wafer procedure had the benefits of less postoperative immobilization and an early return to work. However, there were no significant differences in the postoperative pain improvement and functional scores. All 6 studies reported high total complication rates and reoperation with USO. The most frequent complication was implant-related discomfort or irritation; subsequent plate removal was the most common reason for a secondary operation.

CONCLUSIONS

There was no difference in pain improvement or the postoperative functional score between the groups. Nevertheless, postoperative complications were the major pitfalls of USO. As the specialized shortening system advances further, a high-level study will be necessary to determine the surgical option in UIS.

Refracture after plate removal following ulnar shortening osteotomy for ulnar impaction syndrome - a retrospective case-control study

LEVEL OF EVIDENCE

Level III, case-control study.

Inevitable nonunion after ulnar shortening osteotomy in patients with ulnar impaction syndrome and breast cancer under bisphosphonate treatment

BACKGROUND

Nonunion after ulnar shortening osteotomy (USO) was observed at a high rate in patients undergoing long-term bisphosphonate (BP) maintenance treatment after breast cancer surgery. Here, we report the unique features of these nonunions.

METHODS

In total, 485 patients who had undergone USO between March 2008 and September 2017 were screened for inclusion based on the following criteria: (1) definitive nonunion after USO; (2) prior history of or ongoing BP therapy after the diagnosis of breast cancer; and (3) no evidence of metastasis in the ulna treated with USO, as determined based on the radiological evaluation.

RESULTS

Five patients with histories of breast cancer and subsequent BP treatment were identified; all (100%) of these patients showed definitive nonunion after USO. The mean age was 56.2 years, and all ulnae were on the contralateral side to that of the original breast cancer. Intravenous Ibandronate^® and Zolendronate^® were administrated to one and four patients, respectively. The mean period of administration was 67.8 months. Three patients exhibited suspicious lesions impending atypical fracture on their femurs, and the other two patients were treated by intramedullary nailing after the occurrence of atypical fractures. Radiological evaluation revealed no evidence of a metastatic lesion, including in the musculoskeletal system, in any patient. Osteosynthesis was performed with cancellous iliac bone graft and mean of 4.3 months after osteosynthesis, union in all cases was achieved.

CONCLUSIONS

Problems associated with BP treatment are well known. Even in cases in which the agent is essential for preventing bony metastasis of breast cancer, the normal bony physiology, including bone turnover and healing, is likely to be compromised. In addition to atypical fractures of the femur and ulna, procedures such as USO are likely to be affected by BP. Furthermore, not only a primary iliac bone graft but also other method (oblique osteotomy) should be needed to avoid nonunion during plating in USO.

LEVEL OF EVIDENCE

IV, Retrospective case series.

Entrapment of the Extensor Indicis Proprius Tendon after Open Reduction and Internal Fixation of Distal Ulna: Case Report and Discussion of the Diagnosis and Surgical Result

Entrapment of the extensor indicis proprius (EIP) after open reduction and internal fixation (ORIF) of the distal ulna with a plate and screw construct is rare. By literature review, we found evidence of such complication associated with distal radius fracture, but no past reports relating to the distal ulna. ORIF of the distal ulna is a common procedure for both fracture treatment and deformity correction. Due to the EIP muscle originating primarily from the dorsoradial surface of the distal ulna and the adjacent interosseous membrane, the muscle may be damaged or compressed by a fixation plate during ORIF, resulting in entrapment. We present two case reports of this rare complication, describing the method of clinical diagnosis, surgical treatment, and outcome. Our accompanying cadaver dissection provides an explanation for proper plate positioning during ORIF of the ulna to reduce the risk of EIP entrapment.

Intra-Articular Distal Ulnar Sliding Osteotomy for Ulnar Shortening

Background

Ulnocarpal impaction is the most common reason to perform ulnar shortening osteotomy. There are 3 osteotomy techniques for ulnar shortening: transverse, step-cut, and oblique cut^1-3.First described by Milch⁴ in 1941, extra-articular diaphyseal oblique or transverse shortening is the most frequently performed type of shortening. However, it is associated with a nonunion rate of up to 10%, and irritation by implants requiring removal occurs in up to 28% of cases^5,6. Intra-articular procedures such as the wafer procedure affect the distal ulnar joint surface, which can lead to stiffness of the distal radioulnar joint (DRUJ) due to scar tissue formation and adhesion of the triangular fibrocartilage complex (TFCC)⁷. Lapner et al.⁸ described increased pressure in the DRUJ after the wafer procedure, which may lead to an early onset of osteoarthritis. Complication rates between 8% for open wafer procedures and 21% for arthroscopic wafer procedures have been described⁹.Intra-articular shortening has also been described by Slade and Gillon¹⁰ in 2007 and Hammert et al.¹¹ in 2012 and was tested in cadavers by Greenberg et al.¹² in 2013. This closing wedge technique preserves the distal joint surface of the ulna and also allows for easy correction of the inclination of the hub joint surface of the ulna.In contrast to the technique of Slade, our described osteotomy is steeper and longer proximally, which allows for fixation with >2 screws^13-16. Rapid healing of the metaphyseal bone compared with diaphyseal bone is described, and implant removal is necessary less often^14,17,18.With the described procedure, the interosseous membrane remains untouched, especially the distal oblique bundle, which additionally provides stability of the DRUJ in 40% of patients¹⁹.

Description

A dorso-ulnar approach through the fifth extensor sheath is performed. The ulnocarpal joint and the DRUJ are accessed through an arthrotomy distal and proximal to the TFCC. The foveal attachment of the TFCC and the subsheath of the sixth extensor sheath are visualized. The osteotomy is intra-articular oblique from distal ulnar to proximal radial. Sliding the head of the ulna proximally achieves the desired shortening of up to 5 mm, and the head is fixed using 2, 3, or 4 cannulated headless screws. A slight correction of the axis of the ulnar head is also possible.

Alternatives

An alternative to this procedure is extra-articular osteotomy using a palmar or dorsal ulnar approach. If necessary, additional ulnocarpal procedures can be performed in an open or arthroscopically assisted manner.

Rationale

The shortening takes place only in the articular part of the distal aspect of the ulna. This procedure can easily be combined with TFCC repair, synovectomy of the DRUJ, or repair or reconstruction of the lunotriquetral ligament if needed. Shortening of up to 5 mm is possible.

A Dorsal Approach for Ulnar Shortening Osteotomy

Aim  This study aims to evaluate the long-term complications, results, and patient satisfaction rates of a dorsally approached ulnar shortening osteotomy for ulnar impaction syndrome. Methods  A retrospective chart review of 20 patients was performed. Primary outcomes of interest were subjective, measured using the Patient-Rated Wrist Evaluation (PRWE) score, Disability of the Arm, Shoulder, and Hand (DASH) score, and the third questionnaire about patient satisfaction, composed by the authors. Secondary outcomes included hardware removal due to irritation and other complications. Results  Mean postoperative functional score of PRWE was 28 (standard deviation [SD], 30) and DASH 20 (SD, 26), respectively. Fifteen patients were satisfied with the operation. Removal of hardware was noted in six patients. In one patient plate breakage occurred. Conclusion  Similar postoperative functional scores and complications were seen in patients undergoing an ulnar shortening osteotomy with a dorsally placed plate for ulnar impaction syndrome, compared with other plate placement localizations. The incidence of plate removal is also comparable to previously described results. As the dorsally placed plate and freehand technique, are relatively easy, we feel that it has a place in the treatment of ulnar impaction syndrome. Level of Evidence  Level IV, retrospective cohort study.

Time-Dependent Recovery of Outcome Parameters in Ulnar Shortening for Positive Ulnar Variance: A Prospective Case Series

BACKGROUND

This study evaluates the results of ulnar shortening using the ulna osteotomy locking plate system (UOL; I.T.S. GmbH, Graz, Austria) with special regard to the time-dependent recovery of subjective and objective outcome parameters and surgeons' experiences.

METHODS

Ulnar shortening using the UOL was performed on 11 patients (3 men, 8 women) with an average age of 47 ± 19.6 years. Range of motion (ROM) and grip strength were compared with the contralateral hand. Patient-rated outcomes were measured using a visual analogue scale (VAS) for pain and the Disability of the Arm, Shoulder and Hand (DASH) and the Patient Rated Wrist Evaluation (PRWE) survey for subjective outcomes. Ulnar variance and bony union were assessed using conventional wrist radiographs. The surgeons evaluated intraoperative handling through a standardized feedback form.

RESULTS

ROM improved and grip strength increased significantly between preoperative values and final follow-up. Flexion and supination improved significantly between weeks 8 and 12 and grip strength from week 8 onward. Patient-rated outcomes changed significantly with a final DASH score of 14.2 ± 12.4 and a PRWE score of 24.3 ± 17.0. Pain levels improved significantly with no pain at rest and a mean VAS of 0.8 ± 1.2 during activity. The average amount of shortening was 4.0 ± 1.9 mm with a final ulnar variance of 0.2 ± 1.8 mm. All osteotomies healed with 2 cases of delayed union.

CONCLUSIONS

In ulnar shortening with the UOL, wrist function recovered after an initial decrease from week 8 onward. Subjective outcome parameters showed early recovery and improved continuously over time.

Outcomes of Ulnar Shortening for Ulnar Impaction Syndrome Using the 2.7 mm AO Ulna Shortening Osteotomy System

Background: Ulnar shortening osteotomy is a well-established treatment for ulnar impaction syndrome. Controversy remains regarding the most effective system to achieve efficient bony union, whilst minimising incidence of complications, particularly hardware irritation. We present outcomes at 2 years using the recently released low profile AO osteotomy system.

Methods: 32 consecutive patients with significant pain from ulnar impaction syndrome (idiopathic or post-traumatic), without degenerative changes of the distal radio-ulnar joint, were included. Time to union, range of motion, grip strength, pain and complications were recorded.

Results: Median time to union was 10.14 weeks (9.27–11.01, 95%CI), with one nonunion. Visual Analogue Pain score, grip strength and range of motion improved significantly. No patient experienced hardware irritation. No plate required removal. Positive ulnar variance was reduced by 3.8 mm (mean).

Conclusions: The low profile AO system appears effective in achieving bony union whilst minimising incidence of hardware irritation, at a follow up of 2 years

Prognostic Factors Affecting Union After Ulnar Shortening Osteotomy in Ulnar Impaction Syndrome: A Retrospective Case-Control Study

BACKGROUND

Ulnar shortening osteotomy (USO) is a widely adopted procedure with excellent outcomes. However, delayed union or nonunion has occasionally been observed. The purpose of this retrospective case-control study was to identify variables affecting osseous consolidation after USO in patients with ulnar impaction syndrome.

METHODS

The study included 325 patients who had undergone USO between March 2008 and March 2014. We evaluated the association between union and basic demographic factors as well as preoperative pain (assessed on a visual analog scale [VAS]), range of wrist motion, grip strength, and modified Mayo wrist score. We also assessed the association of union with radiographic variables such as the degree of dorsal subluxation of the ulna, preoperative and postoperative ulnar variance, morphological type of the distal radioulnar joint, gap at the osteotomy site, and presence of newly developed arthritic changes during the follow-up period. Finally, variables associated with operative conditions, such as degeneration of the triangular fibrocartilage complex, use of a parallel double-blade saw, type of plate used for fixation, number of screws, and plate position on the volar or dorsal ulnar surface were investigated.

RESULTS

Ulnar union was achieved in 294 patients (group 1), and 31 patients had delayed union or nonunion (group 2). On univariate and multivariate analyses, smoking, low bone mineral density (BMD), a decreased range of motion of the wrist, and use of a double-blade saw were found to be significant factors for an adverse radiographic outcome (nonunion or delayed union).

CONCLUSIONS

Delayed union or nonunion occurred in about 10% of patients treated with USO. We suggest that it may be preferable to perform USO in nonsmokers, patients with normal bone density, and those without restricted wrist motion. Also, we recommend the use of a single-blade saw when performing the osteotomy.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.