Carpal joint;Navicular bone;Navicular fracture;Internal fixation;Treatment results Currently, external fixation with plaster rest or internal fixation with Herbert screw is still used for nondisplaced fractures of the navicular lumbar region. External fixation with plaster has the disadvantages of long fixation time and various discomforts caused by plaster, and incisional reduction has the disadvantages of large surgical trauma, extensive intraoperative dissection, need to cut part of the navicular ligament, and may affect the blood supply of the navicular bone. In recent years, a new type of Martin screw has been introduced, the main difference between Martin screw and Herbert screw is that Martin screw has a hole inside the screw for inserting a guiding kerf pin. Surgical approach The STT (greater trochanter, lesser trochanter and navicular) joint is exposed as far as possible by dorsal extension of the wrist joint during surgery. The STT joint is positioned under fluoroscopy, and a 5L long skin incision is made palmarly to the STT joint. A 0.8L diameter guide pin is inserted from the STT joint along the long axis of the navicular bone from distal to proximal under fluoroscopy, and fluoroscopy is performed in multiple positions under X-ray to determine the position of the guide pin, which should be located in the center of the navicular bone with the tip just below the proximal navicular bone cortex. The length of the inserted keratoconstrictor pin is measured to determine the length of the screw to be used, the length of the screw = length of the guide keratoconstrictor pin \ 2 L. A special drill is drilled along the guide keratoconstrictor pin, the Martin screw is transferred, the guide keratoconstrictor pin is withdrawn, and the position of the navicular bone and the screw is determined under fluoroscopy. The skin was sutured with one stitch and the forearm was externally fixed with a plaster rest for 3 days. Clinical Data Seventeen patients with navicular fractures, 16 males and 1 female, were treated surgically at the Ludwigshafen Trauma Surgery Center in Germany from January 2000 to December 2001. The mean age at the time of injury was 30 years (14-45 years). There were 9 left-handed, 8 right-handed, and 13 dominant hand injuries. All patients underwent routine preoperative X-ray (frontal, lateral and oblique) and CT examinations, and all navicular fractures were type B2 fractures (Herbert’s type) with no significant displacement. The time interval between injury and surgery was 9 days (3-27 days). All 17 navicular fractures were treated with percutaneous needle-piercing Martin screws for internal fixation. They were followed up from 5 to 18 months (mean 8 months) after surgery. At follow-up, the patients were examined for palmar scars and asked about the use of the affected hand, which was classified as: very good: normal hand function; good: near normal hand function with only slight dysfunction; satisfactory: significant hand dysfunction; and poor: severe hand dysfunction. Bilateral wrist wrist flexion and extension mobility was measured with a protractor. Wrist joint grip strength was measured with a jamar grip strength device, three times per side, and the average value was taken. The pain level was measured with a pain scale, with a pain value of 0 indicating no pain and a pain value of 100 indicating intolerable severe pain. Four postural x-rays (posteroanterior, lateral, 20º ulnar deviation, and stecher) were performed on the affected hand at follow-up to determine whether the navicular bone had healed, the position of the screw, and whether the screw had penetrated the proximal navicular bone cortex. Results All patients had one-stage wound healing without infection, and none of the incisions had scar growth at the time of follow-up. The subjective functional evaluation of the patients: 16 cases were very satisfied and 1 case was satisfied. Pain at rest was 0.2 (0-1) and 0.4 (0-2) on exertion, respectively. The wrist flexion and extension mobility was 132°, which was 98% of the contralateral mobility, and the grip strength was 38K, which was 95% of the contralateral grip strength. The postoperative duration of external fixation in a plaster brace was 3 days (0-7 days). At follow-up, all navicular fractures healed. 15 screws were centrally located in the navicular bone and 2 were mildly deflected. None of the screws had tip penetration. The time to return to work depended on the patient’s occupation, and all patients were able to return to non-manual work using the wrist joint 4 days after surgery, while manual work took 5 weeks to fully recover. There was no case of reoperation to remove the screws. Discussion Previously, the surgical treatment of navicular fractures was internal fixation with an incisional Herbert screw. However, this surgical method has the following disadvantages: large surgical incision, sometimes requiring both palmar and dorsal skin incision, special instrumentation, the need for extensive operator experience, and the possibility of damaging the bone cortex and the navicular interosseous ligament. There are reports of wrist instability after Herbert screw fixation, so the indications for Herbert screw fixation are limited to displaced fractures and navicular fractures with other injuries. For non-displaced navicular fractures, external fixation with a plaster rest is still mostly used for 6-8 weeks. The introduction of the Martin screw has brought a new approach to the treatment of navicular fractures. The screw is perforated in the middle and a guide pin can be inserted in the middle, the diameter of the guide pin varies from 0.8 to 1.1 mm, depending on the screw. The advantage of the new screw fixation is that no other special instruments are needed during the operation. After incision and repositioning, the guiding kerf pin is inserted repeatedly along the long axis of the navicular bone until the position of the guiding pin is satisfactory, and then the screw is drilled, tapped, and drilled along the guiding kerf pin, which greatly reduces the surgical trauma and shortens the postoperative recovery time. The prerequisite for percutaneous needle penetration for internal fixation is a navicular fracture without displacement or via closed reduction. Because of the difficulty of conventional x-ray in diagnosing displaced navicular bone. The CT scan is performed in an oblique tangential position, with the scan plane parallel to the long axis of the navicular bone and a thickness of 1-2 L. The wrist joint should be extremely dorsally extended during surgery to facilitate the exposure of the STT joint and the insertion of the guide pin. The position of the guide pin is very important, as the pin should be located in the middle of the navicular bone with the tip just below the proximal cortex. A needle penetrating the bone cortex will result in the selection of a screw that is too long and penetrates the proximal bone cortex into the radial carpal joint, causing postoperative wrist pain, and a skewed needle will result in a screw that is not in the center of the navicular bone, affecting the compression effect. Judgment of the position of the Kirschner pin was performed in multiple positions of the wrist joint. Postoperatively, the patient is externally fixed in a short time cast, and functional wrist exercises are started 2-3 days after surgery, but without weight bearing. Patients can resume non-manual work after discharge from the hospital. The time for the patient to return to non-manual work was greatly reduced, while the trauma associated with the surgery was greatly reduced. The results of the study showed that:percutaneous perforator internal fixation with good function, no complications and short return to work is a good treatment for nondisplaced navicular fractures.