Three-dimensional bone kinematics in an anterior laxity test of the ankle joint

Questions addressed in this in-vitro study are (1) what are the actual three-dimensional kinematics of talus and calcaneus during an anterior drawer test as performed with the quasi-static anterior ankle tester (QAAT) (2) does laxity measurement with the QAAT represent the true anterior translation of talus relative to the tibia?. Simultaneous measurements were made with the QAAT and a three-dimensional kinematics analysis system in five specimens. The three-dimensional translations and rotations on three axes were analysed at 25, 50 and 100 N of applied anterior load, with increased ligament damage. For four out of five remaining specimens, anterior translation values of talus and calcaneus and values as measured with the QAAT show a significant increase with growing ligament damage and with higher loads. Skeletal motions of talus and calcaneus show great similarity in three different motion axes, with increased ligament damage and at any given load. Skeletal translations and rotations of talus and calcaneus show great similarity during an anterior drawer movement of the ankle joint. Anterior skeletal translation of the talus and calcaneus show fair correlation with the anterior displacements measurements of the QAAT. These QAAT measurements show an overestimation of the laxity value by more than 200% irrespective of the load applied.     

The ankle meter: an instrument for evaluation of anterior talar drawer in ankle sprain

The aim of this study was to work out a clinical test which is possible to measure the anterior talar drawer (ATD) in patients after ankle sprain. The instrument for evaluation was called ankle meter. The instrument consists of two plastic scales (heal scale and tibia scale). The instrument allows quantifying the results of the anterior drawing test. A total of 38 persons (16 men, 22 women) were available as control group. The persons were 28.8±10.1 years old. No proband had any ankle problems in his history. A total of 45 patients (25 males, 20 females) suffering from ankle sprain were included in the study. In these patients stress radiography (147.1 N) was performed to measure the ATD. In control group the clinical measured ATD was 1.7±1.3 mm. Measurement for detect the interobserver validity did not detect significant differences. The ATD of the joint after ankle sprain was significantly higher (8.9±4.3 mm). The difference between healthy and injured ankle in case of an ankle sprain was 7.4±4.2 mm. There was a significant correlation between clinical and radiological measured ATD (R=0.91). The results suggest that it is possible to measure the ATD exactly. The values of the clinical ATD measurement showed a good correlation with the results of stress radiography. Diligent clinical examination in combination with this special test are after this experiences sufficient to classify the severity of injury after ankle sprain.     

Stabilizing effects of ankle bracing under a combination of inversion and axial compression loading

The combined effects of bracing, axial compression and inversion rotation on the ankle-subtalar complexes were evaluated. Ex vivo tests under the load-controlled condition were performed on six cadaver ankle specimens using a six degree-of-freedom fixture. Inversion rotation was measured while subjecting the ankle-subtalar complex to a 2.5 N-m inversion moment and a combination of the testing variables (brace type, no brace, 178 N axial compression load, no compression load, 0° and 20° of plantar flexion) for a total of 16 tests per specimen. Three commercially available braces (two semirigid types and one lace up type) were evaluated. An axial compression load significantly decreased ankle-subtalar motion in unbraced ankles for the tested inversion moment. The contribution of bracing to stabilization of the ankle was smaller in the axial loading condition than in the no axial loading condition. The semirigid braces had greater stabilizing effects in response to the inversion moment than the lace up brace. Stabilizing effects of bracing were significantly greater in 20° of plantar flexion than in 0° of plantar flexion. The most common mechanism for an ankle sprain injury is inversion rotation on a weight-bearing ankle. Therefore, we should not overestimate stabilizing effects of bracing from evaluations of bracing without axial compression loading.     

Ball-and-socket ankle joint

The ball-and-socket ankle joint is a malformation of the ankle in which the articular surface of the talus is hemispherical in both the anteroposterior and lateral projections and has a congruent, concave tibial articular surface. Fourteen patients with this condition were identified retrospectively. Thirteen patients were thought to have the congenital type of ball-and-socket ankle joint which in many was associated with tarsal coalition, short limb, and ray fusion and deletion anomalies. One case of the acquired type, demonstrating less geometric rounding of the talar margins, was seen in a patient with myelomeningocele, probably resulting from sensory and motor deficits. Although the exact etiology of the congenital type is unknown, its association with other malformations suggests that the ball-and-socket ankle joint results from an overall maldevelopment of the ankle and foot.     

Test-retest reliability and minimal detectable change of ankle kinematics and spatiotemporal parameters in MS population

BackgroundMany people with multiple sclerosis (pwMS) experience walking impairments often including foot drop, evident as either reduced dorsiflexion at initial contact and/or at the swing phase of the gait cycle. To measure even subtle differences in ankle kinematics, 3D gait analysis is considered a ‘gold’ standard. However, the psychometric properties of ankle kinematics in the MS population have not yet been examined.ObjectiveThe aim of the study was to examine test-retest relative and absolute reliability of sagittal ankle kinematics and spatiotemporal parameters in two groups of pwMS with different levels of walking impairment.MethodsTwo groups of pwMS underwent 3D gait analysis on two occasions 7–14 days apart. Group A consisted of 21 (14 female) people with Expanded Disability Status Scale (EDSS) 1–3.5 and group B consisted of 28 participants (14 female) with EDSS 4-6. The Intraclass Correlation Coefficient (ICC_2,2), standard error of measurement (SEM) and minimal detectable change (MDC_95%) were calculated for peak dorsiflexion (DF) in swing, ankle angle at initial contact (IC), gait profile score (GPS), walking speed, cadence and step length.ResultsBoth groups presented ‘excellent’ ICC values (>0.75) for DF in swing, IC and step length of most and least affected limbs, walking speed and cadence, with GPS for both limbs exhibiting ‘fair’ to ‘good’ ICCs (0.489–0.698). The MDC_95% values for all ankle kinematic parameters in group A were lower (1.9°–4.2°) than those in group B (2.2°–7.7°).ConclusionThe present results suggest that ankle kinematic and spatiotemporal parameters derived from 3D gait analysis are reliable outcome measures to be used in the MS population. Further, this study provides indices of reliability that can be applied to both clinical decision making and in the design of studies aimed at treating foot drop in people with MS.     

踝关节本体感受器损伤与慢性踝关节不稳定关系的初步研究

Objective To analyze the effect of ankle joint proprioceptor injury on the functional ankle instability. Methods The study enrolled 18 ( 13 males) with chronic ankle instability treated with ligament reconstruction operation. The American Orthopaedic Foot and Ankle Surgeons (AOFAS)score was used for evaluation of the function before and after operation and the balance system evaluate the proprioception function. The two ankle ligament specimens from fresh frozen body and the tissue samples from operation were used for investigation of the structure and distribution of the sensory corpuscles by using histology and immunohistoehemical staining. Results The sections were evaluated with a microscope and an image analyzer. Labeled nerve endings were mapped, measured and categorized. Type Ⅰ ( Ruffini-like ending) , type Ⅱ ( Pacinin-like corpuscle ) and type Ⅳ- (noncorpuscular) nerve endings could be identified in all the lateral ankle ligaments, with majority of types Ⅰ and Ⅱ nerve endings.These receptors were distributed primarily over the superficial ligament and near the bony attachments.There was statistical difference between preoperative and postoperative sway distance as well as between preoperative and postoperative AOFAS score. Conclusions This study suggests that the longer history,severer symptoms and lower AOFAS score may lead to the severer injury of the mechanical proprioceptors.The proprioceptor injury is correlated with ankle joint instability and the ligament reconstruction is effective to avoid the repeated injury of the proprioceptor.     

Arthrography of the ankle joint in chronic instability

Papers on arthrography of injuries of the lateral ligaments of the ankle relate mainly to recent distortion of the joint. Arthrography performed at a later stage after injury generally is considered useless. In fact, changes in chronic instability are observed; they are subtle and consist either of small recesses adjacent to the lateral malleolus or communication of the joint with the peroneal tendon sheaths. Arthrography was assessed in 61 cases of recurrent lateral sprains of the ankle more than 2 weeks after acute injury; 38 were considered as positive. Twenty-five patients had operative evaluation, with four false negative and one false positive results. Small recesses adjacent to the lateral malleolus or opacification of the peroneal tendon sheaths are sequelae of an acute sprain with tear of the anterior talofibular and/or the calcaneofibular ligaments. Although false negative results occur, arthrography is useful in the preoperative assessment of chronic ankle instability.     

Anatomical reconstruction versus tenodesis for the treatment of chronic anterolateral instability of the ankle joint: a 2- to 10-year follow-up, multicenter study

The clinical outcome of anatomical reconstruction or tenodesis in the treatment of chronic anterolateral ankle instability was assessed in a retrospective multicenter study. The anatomical reconstruction group (group A) consisted of 106 patients (mean age at operation 24 ± 8.4 years) and the tenodesis group (group B) of 110 patients (mean age at operation 26 ± 11.4 years). Patients were evaluated at a mean follow-up of 5.5 ± 2.8 years in group A and 5.2 ± 2.9 years in group B. The review protocol included patient characteristics, physical examination, two ankle scoring scales to evaluate the functional results, and standard anteroposterior and lateral radiographs to evaluate degenerative changes. Mechanical stability was evaluated using standardized stress radiographs. A larger number of reoperations was performed in group B (P = 0.008). At physical examination, more patients in group B had a smaller range of ankle motion than those in group A (P = 0.009). ¶A larger proportion of patients in group B had medially located osteophytes, as seen on standard radiographs (P = 0.04). On stress radiographic examination, the mean talar tilt (P = 0.001) and mean anterior talar translation (P < 0.001) were seen to be significantly greater in group B than in group A. There were no differences in mean Karlsson score between the groups, but more patients in group A had an excellent result on the Good score (P = 0.011). Unlike anatomical reconstructions, tenodeses do not restore the normal anatomy of the lateral ankle ligaments. This results in restricted range of ankle motion, reduced long-term stability, an increased risk of medially located degenerative changes, a larger number of reoperations, and less satisfactory overall results.     

Female athletes with ligament dominance exhibiting altered hip and ankle muscle co-contraction patterns compared to healthy individuals during single-leg landing

BackgroundAnterior cruciate ligament (ACL) injury is one of the most serious knee injuries and occurs frequently during exercise. Altered hip and ankle muscle co-contraction patterns may contribute to dynamic knee valgus and ACL injury mechanisms. Lack of dynamic control of ground reaction force (GRF) is known to be contributing factor for ACL injury by placing excessive force on passive structures. Muscle co-contraction is a dynamic mechanism for GRF absorption. Therefore, any alterations in co-contraction might be a risk factor for ACL injury. Ligament dominance is a term to define individuals who rely more on ACL ligament for GRF control.Research questionThis study aimed to compare the muscle co-contraction patterns of distal and proximal knee muscles during single leg landing in female athletes with and without ligament dominance.MethodsThis is a cross-sectional study. A total of 54 female athletes were assigned to the healthy (n = 27) and ligament dominance (n = 27) group based on their Tuck Jump test scores. The electromyography activity of the gluteus medius, adductor longus, tibialis anterior, peroneus longus, medial and lateral gastrocnemius was measured by an electromyography in drop down a 30-cm-high stair. A Multivariate Analysis of Variance (MANOVA) was used for statistical analysis (p ≤ 0.05).ResultsThe two groups demonstrated an overall significantly different muscle co-contraction patterns (P < 0.05). There was a decreased in co-contraction of proximal group and an increased co-contraction in the distal muscles in ligament dominant group.SignificanceThe findings have provided evidence to support the notion of neuromuscular imbalances in ligament dominance deficit. These findings can be useful for the coaches and experts to design preventive exercises and modify the current programs for the people affected by ligament dominance.     

Validity and reliability of video analysis to evaluate ankle proprioceptive reintegration during postural control

BackgroundThe ability to dynamically reintegrate proprioceptive signals after they have been perturbated is impaired in certain pathologies. Evaluation of proprioceptive reintegration is useful for clinical practice but currently requires expensive laboratory tools. We developed a simple method, accessible to clinicians.Research question: Is two-dimensional (2D) video analysis of earlobe displacement a valid and reliable tool for the evaluation of ankle proprioceptive reintegration following muscle vibration?MethodsThirty-eight healthy individuals underwent vibration of the triceps surae while standing on a force plate (FP). Anterior (sagittal plane) earlobe displacement (‘overshoot’) was recorded at vibration cessation using 2D video analysis and rated by 3 blind examiners. Correlation analysis was performed between earlobe and center of pressure displacement (dCoP, recorded with the FP) to determine validity. Intra and interrater reliability were determined by calculation of the intraclass correlation coefficient (ICC), change in the mean (CiM), standard error of measurement (SEM) and the minimal detectable change (MDC).Results and significanceStrong positive correlations (r = 0.82–0.94, p < .001) were found between video and FP data. Intra- and interrater reliability were excellent (ICC from 0.99 to 1.00 and from 0.90 to 0.97 respectively). For intrarater analysis, the CiM was 0.01 cm, SEM were 0.27 cm (95% CI: 0.23–0.33) and 3.43% (95% CI: 2.92–4.20) and the MDC was 0.74 cm. For interrater reliability, the CiM ranged from − 0.81–0.55 cm, the SEM from 0.61 to 1.12 cm and the MDC from 1.69 to 3.10 cm. 2D video analysis of anterior (sagittal) earlobe displacement is therefore a valid and reliable method to assess postural recovery following muscle vibration. This simple method could be used by clinicians to evaluate the ability of the central nervous system to reintegrate proprioceptive signals from the ankle. Further studies are needed to assess its validity in individuals with proprioceptive impairment.     

Ultrasound in acute trauma of the ankle and hindfoot

Ultrasound is a rapid, widely available and inexpensive imaging modality for the evaluation of the ankle and hindfoot. Ultrasonography can be performed in acute, semiacute and chronic conditions. Ankle injuries can be evaluated with ultrasound combined with X-rays. In the emergency room, acute trauma of ankle and hindfoot is an important indication for ultrasound. Electronic Publication     

103例踝关节骨折脱位的治疗

目的：总结踝关节骨折脱位治疗的经验,方法对１９８７－１９９７年１０３例踝关节骨折脱位治疗情况进行分析,随访６个月－５年,平均２年３个月,采用Ｗｅｂｅｒ评分标准评定临床疗效。结果手法治疗３８例：优１３例（３４％）,良１８例（４７％）,差７例（１９％）,优良率为８２％,其中单纯外踝骨折１４例,仅１４％（２／１４）获得解剖复位,但临床疗效优良率达（１３／１４）,手术治疗６５例;优３４例（５２％）良２３例     

Lateral ankle fracture with missed proximal tibiofibular joint instability (Maisonneuve injury)

We present a case of a soccer player who sustained a lateral ankle fracture and the associated proximal anterolateral tibiofibular joint instability (Maisonneuve injury) was overlooked. After a non-contact injury the (incomplete) diagnosis of a lateral malleolar fracture (type Weber B, AO 44-B1) was made and the patient was surgically treated with open reduction and internal fixation including a distal syndesmosis screw. After removal of the syndesmosis screw (six weeks after surgery) the patient suffered from activity-related pain around the fibular head. After thorough clinical and radiologic examination, temporary screw transfixation of the fibular head and capsular repair under meticulous fluoroscopic control of fibular rotation helped to restore patient’s sport activity level. This case report emphasizes the importance of precise clinical examination for detection of a proximal tibiofibular joint instability. Restoration of a well functioning and stable proximal tibiofibular joint may be difficult to achieve in previously operated and missed instabilities. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Instrumented measurement of glenohumeral joint laxity: reliability and normative data

This study assessed shoulder laxity using an instrumented arthrometer. We compared anterior and posterior translations at various force levels to determine the reliability of our measurement technique and to provide normative data in healthy shoulders. Fifty shoulders were assessed for glenohumeral joint laxity in two directions (anterior and posterior) and at four force levels (67, 89, 111, and 134 N). The dependent measure was joint displacement. Laxity values were widely, yet normally, distributed in our group of healthy shoulders. Intraclass correlation coefficients revealed excellent between-trial reliability (0.92) and fair between-session (0.73) and between-examiner (0.74) reliability. The average standard error of measurement between trials (0.56 mm), sessions (1.5 mm), and examiners (1.7 mm) demonstrated an unprecedentedly high degree of precision for quantifying glenohumeral joint laxity. Paired t tests revealed no significant laxity differences between sides (P>0.05), indicating bilateral symmetry. A 2 (direction) x 4 (force) analysis of variance revealed significant differences in laxity between directions (P<0.0001) and force levels (P<0.0001). Our results show that our instrumented technique for quantifying glenohumeral joint laxity is precise and reproducible. Posterior translation was significantly greater than anterior, and a significant increase in translation was observed between increasing levels of force.     

Ankle laxity affects ankle kinematics during a side-cutting task in male collegiate soccer athletes without perceived ankle instability

ObjectivesTo investigate whether ankle joint laxity alone influences lower limb kinematics during a side-cutting task.DesignA cross-sectional study.SettingSports medicine research laboratory.ParticipantsIn total, 66 male collegiate soccer players with history of ankle sprains with no perceived ankle instability were categorised into three groups: no-laxity copers (n = 26), laxity copers (n = 23), and severe-laxity copers (n = 17).Main outcome measuresThe hip, knee, ankle, rearfoot, midfoot, and forefoot kinematic data during the stance phase (0%–100% indicated initial contact to take-off) of a 45° side-cutting task were analysed using one-dimensional statistical parametric mapping.ResultsThe horizontal plane kinematics of the rearfoot differed significantly among the three groups during 30%–91% of the stance phase (P < .05). Severe-laxity copers exhibited a greater external rotation angle than no-laxity copers during 6%–14% and 32%–92% of the stance phase (P < .05).ConclusionOur data suggest that severe ankle joint laxity affects rearfoot horizontal plane kinematics in individuals without perceived ankle instability performing a 45° side-cutting task. These findings could be used by clinicians in developing rehabilitation programs to prevent further ankle sprains in patients with severe ankle joint laxity.     

踝关节本体感受器损伤与慢性踝关节不稳定关系的初步研究

目的 从新鲜尸体和踝关节不稳患者手术中所切取的韧带周围组织入手,分析踝关节周围本体感受器的性质和分布,并进一步与临床病例的生物力学、本体感觉功能检验结果相比较,判断和分析本体感受器受损在功能性踝关节不稳定中的作用.方法18例踝关节不稳患者行韧带重建手术.术前、术后分别行功能评分[美国骨科足踝医师协会(AOFAS)评分],平衡系统评价其本体感觉功能.从2例新鲜冰冻尸体踝关节韧带组织和手术中获取韧带组织标本,应用组织学方法和免疫组化染色观察分析感觉小体的结构特征和分布特点.结果 (1)标本发现Ⅰ型小体、Ⅱ型小体和Ⅳ型游离无神经鞘的神经末梢;这些感受器主要分布于韧带的浅层和近骨附着部.(2)患者重心摆动距离术前、术后睁眼与闭眼检测差异均有统计学意义;患者AOFAS评分手术前后差异有统计学意义.结论(1)踝关节不稳患者本体感觉功能受损,病史越长,症状越严重,功能评分越低,其本体感受受损越严重.(2)韧带感受器受损,与踝关节不稳症状相关联,韧带重建是避免感受器反复损伤的有效方法.

Abstract：

Objective To analyze the effect of ankle joint proprioceptor injury on the functional ankle instability. Methods The study enrolled 18 ( 13 males) with chronic ankle instability treated with ligament reconstruction operation. The American Orthopaedic Foot and Ankle Surgeons (AOFAS)score was used for evaluation of the function before and after operation and the balance system evaluate the proprioception function. The two ankle ligament specimens from fresh frozen body and the tissue samples from operation were used for investigation of the structure and distribution of the sensory corpuscles by using histology and immunohistoehemical staining. Results The sections were evaluated with a microscope and an image analyzer. Labeled nerve endings were mapped, measured and categorized. Type Ⅰ ( Ruffini-like ending) , type Ⅱ ( Pacinin-like corpuscle ) and type Ⅳ- (noncorpuscular) nerve endings could be identified in all the lateral ankle ligaments, with majority of types Ⅰ and Ⅱ nerve endings.These receptors were distributed primarily over the superficial ligament and near the bony attachments.There was statistical difference between preoperative and postoperative sway distance as well as between preoperative and postoperative AOFAS score. Conclusions This study suggests that the longer history,severer symptoms and lower AOFAS score may lead to the severer injury of the mechanical proprioceptors.The proprioceptor injury is correlated with ankle joint instability and the ligament reconstruction is effective to avoid the repeated injury of the proprioceptor.     

Arthroscopic assessment of the chronic unstable ankle joint

The purpose of this study was to evaluate prospectively the findings during arthroscopy in patients with chronic instability of the ankle joint. One hundred and ten consecutive patients who had suffered at least two ankle sprains and were symptomatic for at least 6 months were included in this study. A complete rupture of the anterior talofibular ligament was found in 64%, of the calcancofibular ligament in 41% and of the deltoid ligament in 6%. Cartilage lesions of the talus were seen in 54% of the joints, more of them medial (56%) than lateral (15%) or ventral (20%). Other frequently observed findings were synovialitis (38%), rupture of the syndesmosis (7%), and ventral scarring (6%). While cartilage damage was found independently of the lateral ligament injuries, all complete tears of the deltoid ligament were associated with cartilage injury of the talus. Medial instability was assessed in five ankles clinically and found arthroscopically in 23 ankle joints. Our arthroscopic findings show that chronic instability of the ankle joint is associated with various pathological conditions of ligaments, capsule and cartilage. It can therefore give essential information about the status of the chronic unstable joint with regard to the choice of operative or conservative treatment.     

人工全踝关节置换术治疗踝关节骨关节炎的疗效分析

目的 观察人工全踝关节置换术治疗踝关节骨关节炎的疗效.方法 对1999年10月- 2006年10月所收治的42例患有严重踝关节骨关节炎并符合手术适应证的患者进行人工全踝关节置换术.并按照Kofoed评分标准,对患者的疼痛程度、踝关节功能、踝关节活动度进行评分;同时根据Mayo踝关节置换的评价标准对患者进行疗效评价.结果 根据Kofoed评分标准,术后患者在疼痛、功能和活动度方面都明显优于术前(P＜0.05),优良率为90％ (28/31);而根据Mayo踝关节置换的评价标准,优良率为87％ (27/31).结论 人工全踝置换术能有效缓解踝关节疼痛,改善踝关节活动度及功能,为需行踝关节融合术患者提供一种有效的方法.     

The relationships between instrumented measurements of ankle and knee ligamentous laxity and generalized joint laxity

AIM: The purpose of this study was to evaluate whether lower extremity joint laxity is a function of a particular joint and/or a generalizable characteristic (trait) of the person. Validated instrumented measurements of ankle and knee joint-specific laxity in the same individual were correlated to determine whether a relationship exists. In addition, ankle and knee joint-specific laxity were correlated with generalized joint laxity using the modified Beighton mobility index. METHODS: Fifty-seven male and female athletes were studied. We examined dominant ankle laxity using an ankle arthrometer and dominate knee anterior laxity using the KT 2000. The dominant ankle was loaded in anteroposterior (AP) drawer and inversion-eversion (I-E) rotation. Laxity was measured as total AP displacement (millimeters) after +/-125 N of applied force and total I-E rotation (degrees) was measured after +/-4 N x m of applied torque. The dominant knee was loaded with an anterior drawer and laxity (millimeters) was measured after manual maximum displacement. RESULTS: Non-significant correlations were observed among the test variables for generalized joint laxity (0.21 to 0.37; P>0.05) and instrumented ankle and knee joint laxity (0.19 to 0.21; P>0.05). When examined by gender, no statistically significant correlations (0.05 to 0.40; P>0.05) were found for either generalized laxity or instrumented ankle and knee joint laxity. CONCLUSIONS: These results imply that ankle and knee joint laxity are joint-specific and not generalizable.     

关节镜辅助下足踝关节融合术

目的探讨关节镜辅助下足踝关节融合术的方法与疗效。方法2001年1月-2004年7月，采用关节镜辅助下踝关节融合术13例，距舟关节融合术8例。男15例，女6例；年龄32—68岁，平均41岁。其中踝关节粉碎性骨折伴创伤性骨关节炎6例，地方性大骨节病7例，距舟关节炎8例；左足9例，右足12例。镜下清除踝关节和距舟关节增生肥厚的滑膜和纤维瘢痕组织，磨削骨赘，切除胫骨端、距骨穹隆和内外侧踝穴的软骨和软骨下骨，进行自体骨植骨。为保证骨对骨的密切接触需进行内固定。结果术后均获得随访，时间6～38个月，平均10个月。术后关节无肿胀和疼痛，行走步态和功能明显改善，X线片显示骨性融合。结论关节镜辅助下进行踝关节和距舟关节融合，不仅创伤小、视野清晰、操作简便，而且不破坏周围结构，有利于融合并保留踝穴轮廓。